Evaluation of Radiographic and Computed Tomographic Vertebral Heart Score in Healthy Tatra hound breed

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Agudelo, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8552310/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background: The vertebral heart score (VHS) is widely used to assess cardiac silhouette size in dogs, but breed-specific reference values are needed to improve diagnostic accuracy. No radiographic or computed tomographic (CT) VHS reference values have been established for the Tatra hound. This study aimed to determine breed-specific radiographic and CT VHS values in clinically healthy Tatra hound dogs, evaluate the influence of sex, age, and body weight, and assess the agreement and correlation between VHS measurements obtained from radiography and CT. Results: The mean RTG-VHS was 10.54 ± 0.51 (n = 43) and the mean CT-VHS was 10.36 ± 0.44 (n = 25), with no significant difference between the two modalities (paired t-test, p = 0.0576). No significant correlation was found between RTG-VHS and CT-VHS (r = –0.039). No sex-related differences were detected for either method, and VHS did not correlate with age or body weight. Conclusions: Radiographic and CT VHS values in healthy Tatra hound dogs show close agreement and no systematic difference, but the absence of a linear correlation indicates that individual RTG and CT measurements are not directly interchangeable. These results establish the first modality-specific VHS reference intervals for this breed and support the clinical use of VHS in Tatra hounds. vertebral heart score thoracic radiography computed tomography breed-specific reference values Tatra hound healthy dogs Figures Figure 1 Background Radiographic assessment of cardiac disease in dogs can be challenging due to considerable variability in cardiac silhouette size and shape, which depends primarily on breed, age, and body condition. Subjective evaluation therefore may be less reliable, especially in brachycephalic breeds, puppies, or obese dogs. The vertebral heart score (VHS) method introduced an objective and standardized approach that improves diagnostic accuracy [ 1 ]. Developed by Buchanan and Bücheler in 1995, VHS is based on measuring the long and short cardiac axes on a lateral thoracic radiograph and comparing their sum with the length of thoracic vertebrae [ 2 ]. A VHS value above 10.7 has been described as a moderately accurate indicator of potential cardiac disease [ 3 ]. The method has proven useful for monitoring treatment response in myxomatous mitral valve disease [ 4 , 5 ], for identifying pericardial effusion [ 6 ], and for evaluating dilated cardiomyopathy [ 7 , 8 ]. VHS values also correlate well with echocardiographic and electrocardiographic indices of cardiac size [ 9 ]. Several studies have reported breed-related differences, with brachycephalic dogs consistently exhibiting higher VHS values [ 10 , 11 ]. Other breeds—including the Boxer, Cavalier King Charles Spaniel, and Toy Poodle—also display higher VHS values than originally published reference intervals [ 3 , 12 ]. These findings emphasize the need to establish breed-specific reference ranges, as the use of universal values may lead to misinterpretation and inaccurate diagnosis [ 13 , 14 ]. Despite extensive research on VHS in many breeds, no published data are available regarding the cardiac silhouette size of hound-type breeds or scenthounds. This study focuses on the Tatra hound, the youngest Slovak national dog breed currently undergoing official FCI recognition within Group 6 (scenthounds and related breeds), Section 2 (scenthounds), according to the Slovak Kennel Club. The Tatra hound is a medium-sized breed with a moderately deep, spacious, and well-developed thorax [ 15 ]. Such conformation provides sufficient space for the lungs and heart; however, it may influence the radiographic appearance of the cardiac silhouette, which can appear proportionally larger and elongated in the dorsoventral dimension. For this reason, establishing breed-specific VHS reference values is necessary to enable accurate cardiac size assessment and reduce the risk of misinterpreting physiologically larger silhouettes as pathological. The objectives of this study were to establish radiographic and VHS reference values for clinically healthy Tatra hound dogs, to evaluate the influence of sex, age, and body weight, and to assess agreement between radiographic and CT measurements. Materials and Methods Study design and ethical approval This study was designed as a prospective observational analysis aimed at determining reference VHS values in clinically healthy Tatra hound dogs and comparing VHS measurements obtained from right lateral thoracic radiographs and sagittal CT reconstructions. All dogs were client-owned and presented to the Small Animal Clinic, University of Veterinary Medicine and Pharmacy in Košice as part of the official breed standardization process for the Tatra hound. The study protocol and all procedures were reviewed and approved by the Institutional Animal Ethics Committee of the University of Veterinary Medicine and Pharmacy in Košice (approval number: EKVP/2023-20). Written informed consent for participation was obtained from all dog owners prior to imaging. Study population Only clinically healthy, purebred Tatra hound dogs with an official pedigree certificate were included in the study. Dogs were considered clinically healthy if they exhibited normal findings on physical examination, hematology, serum biochemistry, electrocardiography, and echocardiography. Any dog with evidence of cardiovascular disease or any other significant systemic disorder was excluded from the study. All VHS measurements (both radiographic and CT) were performed by a single evaluator—a veterinarian with several years of experience in diagnostic imaging. The evaluator was blinded to the dogs’ identity, sex, and body weight (single-blinded assessment). Each VHS measurement was performed three times on the same image (radiograph and CT, respectively) in independent repetitions. The arithmetic mean of the three measurements was used for further analysis. This approach was chosen to minimize the effect of intra-observer variability. Systematic assessment of intra-observer variability was not included in the present study. Anesthesia All imaging procedures were performed under general anesthesia following a standardized protocol established by the attending anesthesiologist. The same anesthetic regimen was applied to all dogs to minimize the potential influence of sedation or anesthesia on VHS measurements. Premedication consisted of butorphanol 0.2 mg/kg (Butomidor; Richter Pharma AG, Wels, Austria) combined with medetomidine 15 µg/kg (Cepetor; CP-Pharma Handelsges, Germany). Anesthesia was induced intravenously with propofol (Propofol; Fresenius Kabi GmbH, Graz, Austria) to allow endotracheal intubation. General anesthesia was maintained with a continuous intravenous infusion of propofol at 0.2 mg/kg/min using an infusion pump (Syringe pump SN-50 F6, Hamburg, Germany). Prior to CT examination, dogs were connected to an anesthetic machine, and anesthesia was subsequently maintained using inhaled sevoflurane (Sevoflurane; Baxter Healthcare Corp., Deerfield, IL, USA) delivered in 100% oxygen. The concentration of sevoflurane was titrated individually according to anesthetic depth and vital parameters. Radiographic examination Thoracic radiography was performed using a digital radiographic system (Perform-X F100; Control-X Medical Zrt., Hungary). Exposure parameters (mAs, kVp) for each patient were selected according to a predetermined thoracic imaging protocol. Multiple thoracic images were acquired, and the right lateral projection was used for VHS evaluation. Dogs were positioned in right lateral recumbency, with the thoracic limbs extended cranially to minimize superimposition of the triceps musculature over the cranial thorax. The forelimbs were secured using sandbags. The vertebral column and sternum were maintained at equal distances from the table to ensure proper alignment, and the pelvic limbs were kept in a neutral position. All images were obtained during full inspiration, at maximal thoracic expansion. Measurements were performed following the methodology described by Buchanan and Bücheler (1995) [ 2 ]. The long axis of the heart was measured from the ventral aspect of the tracheal bifurcation (carina) to the cardiac apex. This line divided the cardiac silhouette into cranial and caudal portions. The short axis was measured perpendicular to the long axis at its widest point, typically at the level of the caudal vena cava. Both measured lines were then transposed onto the vertebral column, starting from the cranial edge of the fourth thoracic vertebra and aligned parallel to the spinal axis. The VHS value represented the sum of the lengths of both axes expressed as the number of vertebral bodies they spanned [ 2 ]. All VHS measurements were obtained using the dicomPACS®vet diagnostic software (Version 9.2.10; Oehm und Rehbein GmbH, Rostock, Germany), utilizing digital calipers on DICOM images. The evaluator manually identified the anatomical reference points on the heart, and the software automatically calculated the VHS based on transposition of the measured distances onto the thoracic vertebrae. This system allows accurate, standardized, and reproducible VHS assessment. CT examination A subset of dogs underwent CT examination immediately after the radiographic study. CT scanning was performed in sternal recumbency using a 16-slice CT unit (Philips Access; Philips Healthcare, The Netherlands). Images were acquired using the following parameters: 30 mA, 80 kVp, total acquisition time 9 s, slice thickness 0.8 mm, and a constant acquisition angle. An additional helical acquisition was performed with parameters of 100 mA, 120 kVp, 42.7 s total acquisition time, 0.8-mm slice thickness, pitch 1.25, and a rotation time of 0.75 s. CT images were evaluated using Weasis software (version 4.5.1; University Hospitals of Geneva, Geneva, Switzerland), and sagittal multiplanar reconstructions (MPR) in a soft-tissue window were used for measurement. VHS measurement on CT images was performed according to the methodology described by Timperman et al. (2021) [ 16 ], following the same measurement principles as those originally defined by Buchanan and Bücheler [ 2 ]. All measurements were performed by a single evaluator who was blinded to the dogs’ identity, sex, and body weight. Each measurement was repeated three times, and the mean of the three values was used for further analysis. Statistical analysis Statistical analysis was performed using Microsoft Excel (Microsoft Corporation, USA). Descriptive statistics (mean, standard deviation, minimum, maximum, median, and percentiles) were calculated for all variables. An unpaired t-test was used to compare VHS values between males and females, and a paired t-test was used to compare radiographic and CT measurements. Pearson’s correlation coefficient (r) was used to evaluate associations between VHS, body weight, and age. Statistical significance was set at p < 0.05. Results 3.1. Characterization of the study population A total of 43 clinically healthy Tatra hound dogs were included in the study (15 males and 28 females), ranging in age from 0.7 to 7.1 years (mean ± SD: 2.9 ± 1.9 years) and in body weight from 11.2 to 23.0 kg (mean ± SD: 15.5 ± 2.7 kg). All dogs underwent clinical examination and showed no signs of cardiovascular disease. Radiographic examination was performed in all 43 dogs, while CT examination was carried out in 25 individuals from the same cohort. VHS measurements were obtained from the right lateral thoracic radiographs and from equivalent sagittal multiplanar reconstructions of the CT images. 3.2. Radiographic VHS values The mean RTG-VHS obtained from the right lateral projection was 10.54 ± 0.51, with a range of 9.47 to 11.50 and a median of 10.67. The 25th–75th percentile interval ranged from 10.23 to 10.87, representing the reference interval for this breed. Male dogs had a mean RTG-VHS of 10.70 ± 0.50 (range 9.60–11.50), whereas females showed a mean RTG-VHS of 10.44 ± 0.50 (range 9.47–11.23). The difference between sexes was not statistically significant (unpaired t-test, t = 1.612; df = 38; p = 0.0576). 3.3. CT hodnoty VHS The mean CT-VHS in the 25 clinically healthy dogs was 10.36 ± 0.44, with a range of 9.6 to 11.3 and a median of 10.3. The 25th and 75th percentiles were 10.1 and 10.7, respectively. Male dogs had a mean CT-VHS of 10.39 ± 0.37, whereas females had a mean of 10.34 ± 0.48. The difference between sexes was not statistically significant (unpaired t-test, t = 0.2419; df = 23; p = 0.4055). Descriptive statistics for both radiographic and CT measurements are presented in Table 1, and Figure 1 provides a graphical comparison of radiographic and CT VHS values using a boxplot. Table 1. Descriptive statistics (mean ± SD, min–max, median and interquartile range) of vertebral heart score (VHS) measured on right lateral radiographs and sagittal CT reconstructions in healthy Tatra hound dogs. Parameter n Mean ± SD Range (min–max) Median (IQR) VHS – Radiography (right lateral) 43 10.54 ± 0.51 9.47–11.50 10.67 (10.23–10.87) VHS – Computed Tomography (sagittal slices) 25 10.36 ± 0.44 9.60–11.30 10.30 (10.10–10.70) VHS = vertebral heart score; IQR = interquartile range; CT = computed tomography. 3.4. Statistical comparison of radiographic and CT measurement No statistically significant difference was found between VHS values obtained from radiography and CT (paired t-test, t = 1.660; df = 24; p = 0.0550). The mean radiographic VHS was 10.58 ± 0.51, whereas the mean CT-VHS was 10.36 ± 0.44. Similarly, no significant sex-related difference was identified for radiographic measurements (p = 0.0576), and the difference between males and females was also not significant for CT measurements (p = 0.4055). Detailed statistical comparisons between radiographic and CT measurements, as well as correlation results, are presented in Table 2. Table 2. Statistical analyses comparing VHS measurements obtained by radiography and CT, including sex-based comparisons and Pearson correlation analyses. Comparison Statistical test t, df / r p-value Significance Interpretation RTG vs CT (overall) Paired t-test t = 1.660, df = 24 0.0550 Ns No significant difference between methods Sex differences – RTG Unpaired t-test t=1.612 df=38 p = 0.0576 Ns No significant difference between males and females Sex differences – CT Unpaired t-test t = 0.2419, df = 23 0.4055 Ns No significant difference between males and females Correlation: RTG vs CT Pearson correlation r = –0.039 ns Ns No significant correlation Correlation: VHS vs body weight (CT) Pearson correlation r = 0.0387 ns Ns No significant correlation Correlation: VHS vs body weight (RTG) Pearson correlation r = 0.3268 ns Ns No significant correlation ns = not statistically significant. VHS = vertebral heart score; RTG = right lateral radiographic projection; CT = sagittal multiplanar reconstructions from computed tomography; t = test statistic; df = degrees of freedom; r = Pearson’s correlation coefficient. 3.5. Correlations with body weight and age In the radiographic dataset, no statistically significant correlation was found between VHS and body weight (r = 0.0908; p > 0.05) or between VHS and age (r = –0.0236; p > 0.05). A significant positive correlation was observed only between age and body weight (r = 0.3185; p 0.05) or between VHS and age (r = 0.3268; p > 0.05). Complete results for all correlations are also provided in Table 3. Table 3. Correlation of vertebral heart score (VHS) with body weight and age in healthy Tatra hound dogs. Variables r p-value Significance Interpretation RTG: VHS × body weight 0.0908 > 0.05 Ns No correlation RTG: VHS × age –0.0236 > 0.05 Ns No correlation CT: VHS × body weight 0.0387 > 0.05 Ns No correlation CT: VHS × age 0.3268 > 0.05 Ns No correlation ns = not statistically significant. r = Pearson correlation coefficient. VHS = vertebral heart score; RTG = right lateral radiograph; CT = computed tomography. Discussion This study provides the first VHS dataset for the Tatra hound and compares radiographic and CT measurements in the context of existing knowledge across different dog breeds. The aim was to establish reference values for the youngest Slovak national breed and to assess the consistency of measurements between the two imaging modalities. The mean radiographic VHS was 10.54 ± 0.51, whereas the mean CT-VHS was 10.36 ± 0.44. The difference between modalities was not statistically significant, indicating that both radiography and CT yield comparable results when assessing cardiac silhouette size in clinically healthy dogs. The mean VHS values obtained in our cohort were slightly higher than the generally cited reference value for dogs (9.7 ± 0.5 vertebrae) [ 2 ]. Elevated VHS values have also been reported in several other breeds with varying thoracic conformations. For example, published VHS values in the Pug range from 10.7 ± 0.9 [ 10 ] to 10.09 ± 0.22 [ 17 ] and 11.25 ± 0.62 [ 11 ]. Pomeranians showed VHS values of 10.5 ± 0.99 [ 10 ] and 10.69 ± 0.62 [ 12 ]. In Yorkshire Terriers, VHS values ranged from 9.7 ± 0.5 [ 3 ] to 9.9 ± 0.6 [ 10 ]. Bulldogs and Boston Terriers exhibited markedly higher values, 12.7 ± 1.7 and 11.7 ± 1.4, respectively [ 10 ], whereas Toy Poodles showed 9.94 ± 0.60 [ 12 ]. Breeds with deep or elongated thoraxes also tend to have higher VHS values, including the Boxer (11.6 ± 0.8) and the Labrador Retriever (10.8 ± 0.6) [ 3 ], with additional reports of 10.29 ± 0.04 [ 18 ], 10.21 ± 0.10 [ 17 ], and 10.39 ± 0.19 [ 19 ]. Doberman Pinschers showed values around 10.0 ± 0.6 [ 3 ] to 10.2 ± 0.26 [ 20 ]. VHS values for the Cavalier King Charles Spaniel ranged from 10.6 ± 0.5 [ 3 ] to 10.08 ± 0.56 [ 21 ], while Chihuahuas showed 10.0 ± 0.6 and Norwich Terriers 10.6 ± 0.6 [ 14 ]. The Australian Cattle Dog had a mean VHS of 10.5 ± 0.4 [ 13 ], Indian Spitz ranged from 9.63 ± 0.23 [ 17 ] to 10.21 ± 0.13 [ 19 ], Greyhounds averaged 10.5 ± 0.1, and Rottweilers 9.8 ± 0.1 [ 22 ]. Brittany Spaniels had a value of 10.6 ± 0.2 [ 5 ], and the Rajapalayam Dog had 9.08 [ 23 ]. In American Staffordshire Terriers, VHS ranged from 9.9 to 12.2, with a mean of 10.9 ± 0.6 [ 24 ]. These findings clearly demonstrate substantial interbreed variation in VHS values, which is influenced by thoracic conformation, cardiac orientation, and overall body structure. The Tatra hound is a compact, well-proportioned breed with a moderately deep, well-shaped thorax [ 15 ]. The thoracic cavity provides ample space for the heart and lungs, and the prominent forechest contributes to the overall thoracic volume. Such anatomical characteristics may influence the radiographic appearance of the heart, which may appear relatively larger or elongated in the dorsoventral dimension. A similar influence of thoracic morphology on VHS was described by Soeratanapant et al. (2024), who found that cardiac orientation and thoracic type significantly affect measured VHS values—dogs with deep or narrow thoraxes had higher VHS values than those with broader, barrel-shaped thoraxes [ 25 ]. These observations are in agreement with our results, where the mean VHS in the Tatra hound (10.54 ± 0.51) was slightly above the general reference range for dogs (9.7 ± 0.5). Measurements obtained in our study did not reveal a statistically significant difference between radiographic and CT-derived VHS values (p = 0.055), indicating consistency between modalities in assessing cardiac silhouette size. This finding is in agreement with Timperman et al. (2021), who reported moderate to strong correlations between radiographic and CT VHS in dogs [ 16 ]. However, unlike their study, we examined a different breed (the Tatra hound) and did not apply CT gating. The authors noted that VHS values obtained from gated and non-gated CT scans did not differ markedly, suggesting that gating may not be essential for VHS assessment. Differences between CT- and radiography-derived VHS values may also reflect differences in patient positioning. While radiographs were obtained in right lateral recumbency, CT examinations were performed in sternal recumbency. In this position, the cardiac apex shifts slightly to the left due to cranial displacement of the diaphragmatic dome and dorsal sternum. This anatomical shift can shorten the measured long axis on sagittal CT images, resulting in slightly lower VHS values compared with lateral radiographic projections [ 16 ]. Another source of minor variation is the fact that the CT measurement plane was not strictly standardized but selected subjectively based on the level at which the cardiac silhouette appeared widest, similar to Timperman et al. These methodological differences represent key contributors to variability between CT and radiographic measurements. A similar pattern was observed in our dataset, where CT-VHS values were slightly lower than radiographic values (10.36 ± 0.44 vs. 10.54 ± 0.51). These small discrepancies likely reflect a combination of positional variation and subjectivity in selecting the measurement plane. Therefore, patient positioning should always be considered when interpreting VHS results. VHS remained relatively stable in healthy adult Tatra hounds. Szpinda (2023) reported no significant sex-related differences in VHS among American Staffordshire Terriers, suggesting that sex does not influence cardiac silhouette size in this breed [ 24 ]. Similarly, Colina and Imperador (2015) found no significant sex differences in working Belgian Malinois [ 26 ]. A comparable trend was described by Yaramış et al. (2024), who assessed VHS and cardiac anatomy across multiple breeds using CT and found no significant associations between VHS and body weight, sex, or age (p > 0.05). Although body weight correlated with some thoracic and cardiac dimensions, VHS itself remained independent of these factors [ 27 ]. In our study, no significant correlation was identified between radiographic VHS and body weight (r = 0.0908; p > 0.05) or age (r = − 0.0236; p > 0.05), and no sex-related differences were observed. Likewise, CT-VHS showed no significant differences between males (10.39 ± 0.32) and females (10.34 ± 0.42) and did not correlate with age (r = − 0.0236; p > 0.05) or body weight (r = 0.0387; p > 0.05). These findings confirm that VHS is a relatively stable parameter that is not substantially influenced by basic physical characteristics. Differences between our results and those of Yaramış et al. may be explained by several factors. Their study included dogs of various breeds with diverse body conformations and thoracic shapes, which influence cardiac orientation and silhouette geometry. In contrast, our study focused on a single breed with uniform body structure, which is advantageous because it eliminates interbreed differences and reduces morphological variability. The main limitations of this study include the relatively small sample size, particularly for CT measurements, which may limit the statistical power of some comparisons. Additionally, all measurements were performed by a single evaluator; while this ensured methodological consistency and eliminated inter-observer variability, it did not allow assessment of reproducibility among different observers. Nevertheless, all measurements were performed under standardized technical conditions and according to a unified protocol, and the risk of systematic measurement error was minimized. The findings of this study confirm that both radiography and CT provide reliable information about cardiac silhouette size in the Tatra hound. The reference values established here may serve as a basis for clinical interpretation in healthy individuals of this breed and contribute to more accurate assessment of potential cardiomegaly in future clinical cases. Future research should include a larger population, including dogs with various cardiovascular diseases, to better evaluate the diagnostic value of CT in distinguishing physiological from pathological changes in cardiac size. Additional studies involving multiple evaluators would also be beneficial to assess reproducibility and inter-observer variability of VHS measurements. Conclusions Our study provides the first reference values for the vertebral heart score (VHS) in the Tatra hound and compares measurements obtained from radiography and computed tomography. The results demonstrate that both imaging modalities offer consistent assessments of cardiac silhouette size in clinically healthy individuals. The mean VHS values were slightly higher than the commonly cited reference ranges for dogs, indicating breed-specific differences related to thoracic shape and proportions. These findings highlight the importance of using breed-specific reference values when evaluating cardiac size. The established data may improve the accuracy of both radiographic and CT-based diagnostics and support the early identification of pathological changes in the cardiac silhouette in the Tatra hound. Abbreviations CT – computed tomography VHS – vertebral heart score Declarations Acknowledgements This publication was supported by the Internal Grant Agency of the University of Veterinary Medicine and Pharmacy in Košice (IGA UVLF 08/2025: Radiological study of the thoracic cavity in the Slovak national dog breed Tatra hound ). The authors thank all participating dog owners for their cooperation. Funding This study was funded by the Internal Grant Agency of the University of Veterinary Medicine and Pharmacy in Košice (IGA UVLF 08/2025). Author Information Authors and Affiliations Veterinary Teaching Hospital, University of Veterinary Medicine and Pharmacy in Košice, Košice, Slovak Republic G. Kacková, M. Figurová, Vargová, Ľ. Horňáková, S. Horňák Small Animal Referral Centre Sibra, AniCura, Bratislava, Slovak Republic C. F. Agudelo Authors contributions G.K. participated in study coordination, performed radiographic examinations, and prepared the manuscript. M.F. performed CT examinations and contributed to methodological design. C.F.A. conducted clinical assessments including echocardiographic and electrocardiographic examinations. N.V. coordinated the acquisition and recruitment of study animals. S.H. designed the study, performed statistical analyses, interpreted the data, and critically revised the manuscript. L.H. was responsible for the statistical analysis and interpretation of the data. All authors have read and approved the final version of the manuscript. Corresponding author Correspondence to S. Hornak. Ethical approval and consent to participate The study was approved by the Ethics Committee of the University of Veterinary Medicine and Pharmacy in Košice (approval number: EKVP/2023-20). Written informed consent for participation was obtained from all dog owners. Consent for publication Written informed consent from the dog’s owner was obtained for the publication. Competing interests The authors declare that they have no competing interests. Availability of data and materials The datasets generated and analyzed during the current study are available from the corresponding author on reasonable request. References Lamb CR, Tyler M, Boswood A, Skelly BJ, Cain M. 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Szpinda O, Parzeniecka-Jaworska M, Czopowicz M, Jońska I, Bonecka J, Jank M. Cardiological Reference Intervals in Adult American Staffordshire Terrier Dogs. Animals. 2023;13:2436. doi: 10.3390/ani13152436. Soeratanapant S. Reliability of cardiac measurement by vertebral heart score among different thoracic types of dogs. Chulalongkorn University Theses and Dissertations (Chula ETD). 2023.doi: 10.58837/CHULA.THE.2023.1069. Colina CV, do Imperador B de G. Vertebral heart size in healthy Belgian Malinois dogs. J Vet Adv. 2015;5:1176–80. doi: 10.5455/jva.20151214094007. Yaramış ÇP, Erdikmen DO, Altundağ Y, Özkan E, Güzel BC. Examination of the vertebral heart scale and anatomical structure of different dog breeds by computed tomography. Kafkas Univ Vet Fak Derg. 2024;30(3):305–310. doi:10.9775/kvfd.2023.30599. Additional Declarations No competing interests reported. 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Agudelo","email":"","orcid":"","institution":"University of Veterinary Medicine in Košice","correspondingAuthor":false,"prefix":"","firstName":"Carlos","middleName":"F.","lastName":"Agudelo","suffix":""},{"id":578848784,"identity":"0df6d980-c71f-4a87-bca8-28a940c5b8dc","order_by":3,"name":"Nela Vargová","email":"","orcid":"","institution":"University of Veterinary Medicine in Košice","correspondingAuthor":false,"prefix":"","firstName":"Nela","middleName":"","lastName":"Vargová","suffix":""},{"id":578848786,"identity":"bdd05165-b4ba-4bb4-860f-9cbb5cc0d765","order_by":4,"name":"Ľubica Horňáková","email":"","orcid":"","institution":"University of Veterinary Medicine in Košice","correspondingAuthor":false,"prefix":"","firstName":"Ľubica","middleName":"","lastName":"Horňáková","suffix":""},{"id":578848787,"identity":"d5ae2dda-06af-4aa1-81c4-2b1bfccd10d7","order_by":5,"name":"Slavomír 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17:40:04","extension":"xml","order_by":5,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":86540,"visible":true,"origin":"","legend":"","description":"","filename":"02f23d1255f94297a6d0b58d2530ea591structuring.xml","url":"https://assets-eu.researchsquare.com/files/rs-8552310/v1/ff33c8ef925ceb360a8b3150.xml"},{"id":101158733,"identity":"9a9df34f-de57-4358-8f45-476e695e741e","added_by":"auto","created_at":"2026-01-26 17:39:55","extension":"html","order_by":6,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":98038,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-8552310/v1/d4362975264bf9e06e7c9e16.html"},{"id":101206262,"identity":"094c448a-d8da-400c-a228-72b99ed91485","added_by":"auto","created_at":"2026-01-27 09:55:49","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":110364,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eBoxplot of radiographic and CT vertebral heart scores in healthy Tatra hound dogs.\u003c/strong\u003e\u003cbr\u003e\nThe boxes represent the interquartile range (IQR), the horizontal line within each box indicates the median, and the whiskers show the minimum and maximum VHS values.\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-8552310/v1/3525db7cdce7f37782371b9d.png"},{"id":101493966,"identity":"e57f495f-09ed-4940-8a12-84731f2126c5","added_by":"auto","created_at":"2026-01-30 11:42:32","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":909727,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8552310/v1/f909315c-00c1-4b55-b304-6391ee451def.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Evaluation of Radiographic and Computed Tomographic Vertebral Heart Score in Healthy Tatra hound breed","fulltext":[{"header":"Background","content":"\u003cp\u003eRadiographic assessment of cardiac disease in dogs can be challenging due to considerable variability in cardiac silhouette size and shape, which depends primarily on breed, age, and body condition. Subjective evaluation therefore may be less reliable, especially in brachycephalic breeds, puppies, or obese dogs. The vertebral heart score (VHS) method introduced an objective and standardized approach that improves diagnostic accuracy [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Developed by Buchanan and B\u0026uuml;cheler in 1995, VHS is based on measuring the long and short cardiac axes on a lateral thoracic radiograph and comparing their sum with the length of thoracic vertebrae [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. A VHS value above 10.7 has been described as a moderately accurate indicator of potential cardiac disease [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. The method has proven useful for monitoring treatment response in myxomatous mitral valve disease [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e], for identifying pericardial effusion [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e], and for evaluating dilated cardiomyopathy [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. VHS values also correlate well with echocardiographic and electrocardiographic indices of cardiac size [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eSeveral studies have reported breed-related differences, with brachycephalic dogs consistently exhibiting higher VHS values [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Other breeds\u0026mdash;including the Boxer, Cavalier King Charles Spaniel, and Toy Poodle\u0026mdash;also display higher VHS values than originally published reference intervals [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. These findings emphasize the need to establish breed-specific reference ranges, as the use of universal values may lead to misinterpretation and inaccurate diagnosis [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. Despite extensive research on VHS in many breeds, no published data are available regarding the cardiac silhouette size of hound-type breeds or scenthounds.\u003c/p\u003e \u003cp\u003eThis study focuses on the Tatra hound, the youngest Slovak national dog breed currently undergoing official FCI recognition within Group 6 (scenthounds and related breeds), Section 2 (scenthounds), according to the Slovak Kennel Club. The Tatra hound is a medium-sized breed with a moderately deep, spacious, and well-developed thorax [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Such conformation provides sufficient space for the lungs and heart; however, it may influence the radiographic appearance of the cardiac silhouette, which can appear proportionally larger and elongated in the dorsoventral dimension. For this reason, establishing breed-specific VHS reference values is necessary to enable accurate cardiac size assessment and reduce the risk of misinterpreting physiologically larger silhouettes as pathological.\u003c/p\u003e \u003cp\u003eThe objectives of this study were to establish radiographic and VHS reference values for clinically healthy Tatra hound dogs, to evaluate the influence of sex, age, and body weight, and to assess agreement between radiographic and CT measurements.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cp\u003eStudy design and ethical approval\u003c/p\u003e \u003cp\u003eThis study was designed as a prospective observational analysis aimed at determining reference VHS values in clinically healthy Tatra hound dogs and comparing VHS measurements obtained from right lateral thoracic radiographs and sagittal CT reconstructions. All dogs were client-owned and presented to the Small Animal Clinic, University of Veterinary Medicine and Pharmacy in Košice as part of the official breed standardization process for the Tatra hound.\u003c/p\u003e \u003cp\u003eThe study protocol and all procedures were reviewed and approved by the Institutional Animal Ethics Committee of the University of Veterinary Medicine and Pharmacy in Košice (approval number: EKVP/2023-20). Written informed consent for participation was obtained from all dog owners prior to imaging.\u003c/p\u003e \u003cp\u003eStudy population\u003c/p\u003e \u003cp\u003eOnly clinically healthy, purebred Tatra hound dogs with an official pedigree certificate were included in the study. Dogs were considered clinically healthy if they exhibited normal findings on physical examination, hematology, serum biochemistry, electrocardiography, and echocardiography. Any dog with evidence of cardiovascular disease or any other significant systemic disorder was excluded from the study.\u003c/p\u003e \u003cp\u003eAll VHS measurements (both radiographic and CT) were performed by a single evaluator\u0026mdash;a veterinarian with several years of experience in diagnostic imaging. The evaluator was blinded to the dogs\u0026rsquo; identity, sex, and body weight (single-blinded assessment). Each VHS measurement was performed three times on the same image (radiograph and CT, respectively) in independent repetitions. The arithmetic mean of the three measurements was used for further analysis. This approach was chosen to minimize the effect of intra-observer variability. Systematic assessment of intra-observer variability was not included in the present study.\u003c/p\u003e \u003cp\u003eAnesthesia\u003c/p\u003e \u003cp\u003eAll imaging procedures were performed under general anesthesia following a standardized protocol established by the attending anesthesiologist. The same anesthetic regimen was applied to all dogs to minimize the potential influence of sedation or anesthesia on VHS measurements. Premedication consisted of butorphanol 0.2 mg/kg (Butomidor; Richter Pharma AG, Wels, Austria) combined with medetomidine 15 \u0026micro;g/kg (Cepetor; CP-Pharma Handelsges, Germany). Anesthesia was induced intravenously with propofol (Propofol; Fresenius Kabi GmbH, Graz, Austria) to allow endotracheal intubation.\u003c/p\u003e \u003cp\u003eGeneral anesthesia was maintained with a continuous intravenous infusion of propofol at 0.2 mg/kg/min using an infusion pump (Syringe pump SN-50 F6, Hamburg, Germany). Prior to CT examination, dogs were connected to an anesthetic machine, and anesthesia was subsequently maintained using inhaled sevoflurane (Sevoflurane; Baxter Healthcare Corp., Deerfield, IL, USA) delivered in 100% oxygen. The concentration of sevoflurane was titrated individually according to anesthetic depth and vital parameters.\u003c/p\u003e \u003cp\u003eRadiographic examination\u003c/p\u003e \u003cp\u003eThoracic radiography was performed using a digital radiographic system (Perform-X F100; Control-X Medical Zrt., Hungary). Exposure parameters (mAs, kVp) for each patient were selected according to a predetermined thoracic imaging protocol. Multiple thoracic images were acquired, and the right lateral projection was used for VHS evaluation. Dogs were positioned in right lateral recumbency, with the thoracic limbs extended cranially to minimize superimposition of the triceps musculature over the cranial thorax. The forelimbs were secured using sandbags. The vertebral column and sternum were maintained at equal distances from the table to ensure proper alignment, and the pelvic limbs were kept in a neutral position. All images were obtained during full inspiration, at maximal thoracic expansion.\u003c/p\u003e \u003cp\u003eMeasurements were performed following the methodology described by Buchanan and B\u0026uuml;cheler (1995) [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. The long axis of the heart was measured from the ventral aspect of the tracheal bifurcation (carina) to the cardiac apex. This line divided the cardiac silhouette into cranial and caudal portions. The short axis was measured perpendicular to the long axis at its widest point, typically at the level of the caudal vena cava. Both measured lines were then transposed onto the vertebral column, starting from the cranial edge of the fourth thoracic vertebra and aligned parallel to the spinal axis. The VHS value represented the sum of the lengths of both axes expressed as the number of vertebral bodies they spanned [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAll VHS measurements were obtained using the dicomPACS\u0026reg;vet diagnostic software (Version 9.2.10; Oehm und Rehbein GmbH, Rostock, Germany), utilizing digital calipers on DICOM images. The evaluator manually identified the anatomical reference points on the heart, and the software automatically calculated the VHS based on transposition of the measured distances onto the thoracic vertebrae. This system allows accurate, standardized, and reproducible VHS assessment.\u003c/p\u003e \u003cp\u003eCT examination\u003c/p\u003e \u003cp\u003eA subset of dogs underwent CT examination immediately after the radiographic study. CT scanning was performed in sternal recumbency using a 16-slice CT unit (Philips Access; Philips Healthcare, The Netherlands). Images were acquired using the following parameters: 30 mA, 80 kVp, total acquisition time 9 s, slice thickness 0.8 mm, and a constant acquisition angle. An additional helical acquisition was performed with parameters of 100 mA, 120 kVp, 42.7 s total acquisition time, 0.8-mm slice thickness, pitch 1.25, and a rotation time of 0.75 s. CT images were evaluated using Weasis software (version 4.5.1; University Hospitals of Geneva, Geneva, Switzerland), and sagittal multiplanar reconstructions (MPR) in a soft-tissue window were used for measurement.\u003c/p\u003e \u003cp\u003eVHS measurement on CT images was performed according to the methodology described by Timperman et al. (2021) [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e], following the same measurement principles as those originally defined by Buchanan and B\u0026uuml;cheler [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. All measurements were performed by a single evaluator who was blinded to the dogs\u0026rsquo; identity, sex, and body weight. Each measurement was repeated three times, and the mean of the three values was used for further analysis.\u003c/p\u003e \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eStatistical analysis was performed using Microsoft Excel (Microsoft Corporation, USA). Descriptive statistics (mean, standard deviation, minimum, maximum, median, and percentiles) were calculated for all variables. An unpaired t-test was used to compare VHS values between males and females, and a paired t-test was used to compare radiographic and CT measurements. Pearson\u0026rsquo;s correlation coefficient (r) was used to evaluate associations between VHS, body weight, and age. Statistical significance was set at p\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003ch3\u003e3.1. Characterization of the study population\u003c/h3\u003e\n\u003cp\u003eA total of 43 clinically healthy Tatra hound dogs were included in the study (15 males and 28 females), ranging in age from 0.7 to 7.1 years (mean \u0026plusmn; SD: 2.9 \u0026plusmn; 1.9 years) and in body weight from 11.2 to 23.0 kg (mean \u0026plusmn; SD: 15.5 \u0026plusmn; 2.7 kg). All dogs underwent clinical examination and showed no signs of cardiovascular disease. Radiographic examination was performed in all 43 dogs, while CT examination was carried out in 25 individuals from the same cohort. VHS measurements were obtained from the right lateral thoracic radiographs and from equivalent sagittal multiplanar reconstructions of the CT images.\u003c/p\u003e\n\u003ch3\u003e3.2. Radiographic VHS values\u003c/h3\u003e\n\u003cp\u003eThe mean RTG-VHS obtained from the right lateral projection was 10.54 \u0026plusmn; 0.51, with a range of 9.47 to 11.50 and a median of 10.67. The 25th\u0026ndash;75th percentile interval ranged from 10.23 to 10.87, representing the reference interval for this breed.\u003c/p\u003e\n\u003cp\u003eMale dogs had a mean RTG-VHS of 10.70 \u0026plusmn; 0.50 (range 9.60\u0026ndash;11.50), whereas females showed a mean RTG-VHS of 10.44 \u0026plusmn; 0.50 (range 9.47\u0026ndash;11.23). The difference between sexes was not statistically significant (unpaired t-test, t = 1.612; df = 38; p = 0.0576).\u003c/p\u003e\n\u003ch3\u003e3.3. CT hodnoty VHS\u003c/h3\u003e\n\u003cp\u003eThe mean CT-VHS in the 25 clinically healthy dogs was 10.36 \u0026plusmn; 0.44, with a range of 9.6 to 11.3 and a median of 10.3. The 25th and 75th percentiles were 10.1 and 10.7, respectively. Male dogs had a mean CT-VHS of 10.39 \u0026plusmn; 0.37, whereas females had a mean of 10.34 \u0026plusmn; 0.48. The difference between sexes was not statistically significant (unpaired t-test, t = 0.2419; df = 23; p = 0.4055).\u003c/p\u003e\n\u003cp\u003eDescriptive statistics for both radiographic and CT measurements are presented in Table 1, and Figure 1 provides a graphical comparison of radiographic and CT VHS values using a boxplot.\u003c/p\u003e\n\u003cp\u003eTable 1. Descriptive statistics (mean \u0026plusmn; SD, min\u0026ndash;max, median and interquartile range) of vertebral heart score (VHS) measured on right lateral radiographs and sagittal CT reconstructions in healthy Tatra hound dogs.\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eParameter\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003en\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eMean \u0026plusmn; SD\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eRange (min\u0026ndash;max)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eMedian (IQR)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eVHS \u0026ndash; Radiography (right lateral)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e43\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e10.54 \u0026plusmn; 0.51\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e9.47\u0026ndash;11.50\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e10.67 (10.23\u0026ndash;10.87)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eVHS \u0026ndash; Computed Tomography (sagittal slices)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e10.36 \u0026plusmn; 0.44\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e9.60\u0026ndash;11.30\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003e10.30 (10.10\u0026ndash;10.70)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eVHS = vertebral heart score; IQR = interquartile range; CT = computed tomography.\u003c/p\u003e\n\u003ch3\u003e3.4. Statistical comparison of radiographic and CT measurement\u003c/h3\u003e\n\u003cp\u003eNo statistically significant difference was found between VHS values obtained from radiography and CT (paired t-test, t = 1.660; df = 24; p = 0.0550). The mean radiographic VHS was 10.58 \u0026plusmn; 0.51, whereas the mean CT-VHS was 10.36 \u0026plusmn; 0.44.\u003c/p\u003e\n\u003cp\u003eSimilarly, no significant sex-related difference was identified for radiographic measurements (p = 0.0576), and the difference between males and females was also not significant for CT measurements (p = 0.4055).\u003c/p\u003e\n\u003cp\u003eDetailed statistical comparisons between radiographic and CT measurements, as well as correlation results, are presented in Table 2.\u003c/p\u003e\n\u003cp\u003eTable 2. Statistical analyses comparing VHS measurements obtained by radiography and CT, including sex-based comparisons and Pearson correlation analyses.\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" class=\"fr-table-selection-hover\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eComparison\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eStatistical test\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003et, df / r\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003ep-value\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eSignificance\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eInterpretation\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eRTG vs CT (overall)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003ePaired t-test\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003et = 1.660, df = 24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.0550\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNs\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNo significant difference between methods\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eSex differences \u0026ndash; RTG\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eUnpaired t-test\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003et=1.612 df=38\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003ep = 0.0576\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNs\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNo significant difference between males and females\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eSex differences \u0026ndash; CT\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eUnpaired t-test\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003et = 0.2419, df = 23\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.4055\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNs\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNo significant difference between males and females\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eCorrelation: RTG vs CT\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003ePearson correlation\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003er = \u0026ndash;0.039\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNs\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNo significant correlation\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eCorrelation: VHS vs body weight (CT)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003ePearson correlation\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003er = 0.0387\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNs\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNo significant correlation\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eCorrelation: VHS vs body weight (RTG)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003ePearson correlation\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003er = 0.3268\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003ens\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNs\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNo significant correlation\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003ens = not statistically significant. VHS = vertebral heart score; RTG = right lateral radiographic projection; CT = sagittal multiplanar reconstructions from computed tomography; t = test statistic; df = degrees of freedom; r = Pearson\u0026rsquo;s correlation coefficient.\u003c/p\u003e\n\u003ch3\u003e3.5. Correlations with body weight and age\u003c/h3\u003e\n\u003cp\u003eIn the radiographic dataset, no statistically significant correlation was found between VHS and body weight (r = 0.0908; p \u0026gt; 0.05) or between VHS and age (r = \u0026ndash;0.0236; p \u0026gt; 0.05). A significant positive correlation was observed only between age and body weight (r = 0.3185; p \u0026lt; 0.05). Detailed correlation results are presented in Table 3.\u003c/p\u003e\n\u003cp\u003eSimilarly, in the CT dataset, no significant correlation was identified between VHS and body weight (r = 0.0387; p \u0026gt; 0.05) or between VHS and age (r = 0.3268; p \u0026gt; 0.05). Complete results for all correlations are also provided in Table 3.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTable 3. Correlation of vertebral heart score (VHS) with body weight and age in healthy Tatra hound dogs.\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eVariables\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003er\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003ep-value\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eSignificance\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eInterpretation\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eRTG: VHS \u0026times; body weight\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.0908\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026gt; 0.05\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNs\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNo correlation\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eRTG: VHS \u0026times; age\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026ndash;0.0236\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026gt; 0.05\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNs\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNo correlation\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCT: VHS \u0026times; body weight\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.0387\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026gt; 0.05\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNs\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNo correlation\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eCT: VHS \u0026times; age\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e0.3268\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003e\u0026gt; 0.05\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNs\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\"\u003e\n \u003cp\u003eNo correlation\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u0026nbsp;ns = not statistically significant. r = Pearson correlation coefficient. VHS = vertebral heart score; RTG = right lateral radiograph; CT = computed tomography.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis study provides the first VHS dataset for the Tatra hound and compares radiographic and CT measurements in the context of existing knowledge across different dog breeds. The aim was to establish reference values for the youngest Slovak national breed and to assess the consistency of measurements between the two imaging modalities. The mean radiographic VHS was 10.54\u0026thinsp;\u0026plusmn;\u0026thinsp;0.51, whereas the mean CT-VHS was 10.36\u0026thinsp;\u0026plusmn;\u0026thinsp;0.44. The difference between modalities was not statistically significant, indicating that both radiography and CT yield comparable results when assessing cardiac silhouette size in clinically healthy dogs.\u003c/p\u003e \u003cp\u003eThe mean VHS values obtained in our cohort were slightly higher than the generally cited reference value for dogs (9.7\u0026thinsp;\u0026plusmn;\u0026thinsp;0.5 vertebrae) [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Elevated VHS values have also been reported in several other breeds with varying thoracic conformations. For example, published VHS values in the Pug range from 10.7\u0026thinsp;\u0026plusmn;\u0026thinsp;0.9 [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e] to 10.09\u0026thinsp;\u0026plusmn;\u0026thinsp;0.22 [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e] and 11.25\u0026thinsp;\u0026plusmn;\u0026thinsp;0.62 [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Pomeranians showed VHS values of 10.5\u0026thinsp;\u0026plusmn;\u0026thinsp;0.99 [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e] and 10.69\u0026thinsp;\u0026plusmn;\u0026thinsp;0.62 [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. In Yorkshire Terriers, VHS values ranged from 9.7\u0026thinsp;\u0026plusmn;\u0026thinsp;0.5 [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e] to 9.9\u0026thinsp;\u0026plusmn;\u0026thinsp;0.6 [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Bulldogs and Boston Terriers exhibited markedly higher values, 12.7\u0026thinsp;\u0026plusmn;\u0026thinsp;1.7 and 11.7\u0026thinsp;\u0026plusmn;\u0026thinsp;1.4, respectively [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e], whereas Toy Poodles showed 9.94\u0026thinsp;\u0026plusmn;\u0026thinsp;0.60 [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Breeds with deep or elongated thoraxes also tend to have higher VHS values, including the Boxer (11.6\u0026thinsp;\u0026plusmn;\u0026thinsp;0.8) and the Labrador Retriever (10.8\u0026thinsp;\u0026plusmn;\u0026thinsp;0.6) [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e], with additional reports of 10.29\u0026thinsp;\u0026plusmn;\u0026thinsp;0.04 [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e], 10.21\u0026thinsp;\u0026plusmn;\u0026thinsp;0.10 [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e], and 10.39\u0026thinsp;\u0026plusmn;\u0026thinsp;0.19 [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Doberman Pinschers showed values around 10.0\u0026thinsp;\u0026plusmn;\u0026thinsp;0.6 [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e] to 10.2\u0026thinsp;\u0026plusmn;\u0026thinsp;0.26 [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. VHS values for the Cavalier King Charles Spaniel ranged from 10.6\u0026thinsp;\u0026plusmn;\u0026thinsp;0.5 [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e] to 10.08\u0026thinsp;\u0026plusmn;\u0026thinsp;0.56 [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e], while Chihuahuas showed 10.0\u0026thinsp;\u0026plusmn;\u0026thinsp;0.6 and Norwich Terriers 10.6\u0026thinsp;\u0026plusmn;\u0026thinsp;0.6 [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. The Australian Cattle Dog had a mean VHS of 10.5\u0026thinsp;\u0026plusmn;\u0026thinsp;0.4 [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e], Indian Spitz ranged from 9.63\u0026thinsp;\u0026plusmn;\u0026thinsp;0.23 [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e] to 10.21\u0026thinsp;\u0026plusmn;\u0026thinsp;0.13 [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e], Greyhounds averaged 10.5\u0026thinsp;\u0026plusmn;\u0026thinsp;0.1, and Rottweilers 9.8\u0026thinsp;\u0026plusmn;\u0026thinsp;0.1 [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. Brittany Spaniels had a value of 10.6\u0026thinsp;\u0026plusmn;\u0026thinsp;0.2 [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e], and the Rajapalayam Dog had 9.08 [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. In American Staffordshire Terriers, VHS ranged from 9.9 to 12.2, with a mean of 10.9\u0026thinsp;\u0026plusmn;\u0026thinsp;0.6 [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThese findings clearly demonstrate substantial interbreed variation in VHS values, which is influenced by thoracic conformation, cardiac orientation, and overall body structure. The Tatra hound is a compact, well-proportioned breed with a moderately deep, well-shaped thorax [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. The thoracic cavity provides ample space for the heart and lungs, and the prominent forechest contributes to the overall thoracic volume. Such anatomical characteristics may influence the radiographic appearance of the heart, which may appear relatively larger or elongated in the dorsoventral dimension. A similar influence of thoracic morphology on VHS was described by Soeratanapant et al. (2024), who found that cardiac orientation and thoracic type significantly affect measured VHS values\u0026mdash;dogs with deep or narrow thoraxes had higher VHS values than those with broader, barrel-shaped thoraxes [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. These observations are in agreement with our results, where the mean VHS in the Tatra hound (10.54\u0026thinsp;\u0026plusmn;\u0026thinsp;0.51) was slightly above the general reference range for dogs (9.7\u0026thinsp;\u0026plusmn;\u0026thinsp;0.5).\u003c/p\u003e \u003cp\u003eMeasurements obtained in our study did not reveal a statistically significant difference between radiographic and CT-derived VHS values (p\u0026thinsp;=\u0026thinsp;0.055), indicating consistency between modalities in assessing cardiac silhouette size. This finding is in agreement with Timperman et al. (2021), who reported moderate to strong correlations between radiographic and CT VHS in dogs [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. However, unlike their study, we examined a different breed (the Tatra hound) and did not apply CT gating. The authors noted that VHS values obtained from gated and non-gated CT scans did not differ markedly, suggesting that gating may not be essential for VHS assessment. Differences between CT- and radiography-derived VHS values may also reflect differences in patient positioning. While radiographs were obtained in right lateral recumbency, CT examinations were performed in sternal recumbency. In this position, the cardiac apex shifts slightly to the left due to cranial displacement of the diaphragmatic dome and dorsal sternum. This anatomical shift can shorten the measured long axis on sagittal CT images, resulting in slightly lower VHS values compared with lateral radiographic projections [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Another source of minor variation is the fact that the CT measurement plane was not strictly standardized but selected subjectively based on the level at which the cardiac silhouette appeared widest, similar to Timperman et al. These methodological differences represent key contributors to variability between CT and radiographic measurements. A similar pattern was observed in our dataset, where CT-VHS values were slightly lower than radiographic values (10.36\u0026thinsp;\u0026plusmn;\u0026thinsp;0.44 vs. 10.54\u0026thinsp;\u0026plusmn;\u0026thinsp;0.51). These small discrepancies likely reflect a combination of positional variation and subjectivity in selecting the measurement plane. Therefore, patient positioning should always be considered when interpreting VHS results.\u003c/p\u003e \u003cp\u003eVHS remained relatively stable in healthy adult Tatra hounds. Szpinda (2023) reported no significant sex-related differences in VHS among American Staffordshire Terriers, suggesting that sex does not influence cardiac silhouette size in this breed [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. Similarly, Colina and Imperador (2015) found no significant sex differences in working Belgian Malinois [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. A comparable trend was described by Yaramış et al. (2024), who assessed VHS and cardiac anatomy across multiple breeds using CT and found no significant associations between VHS and body weight, sex, or age (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05). Although body weight correlated with some thoracic and cardiac dimensions, VHS itself remained independent of these factors [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. In our study, no significant correlation was identified between radiographic VHS and body weight (r\u0026thinsp;=\u0026thinsp;0.0908; p\u0026thinsp;\u0026gt;\u0026thinsp;0.05) or age (r = \u0026minus;\u0026thinsp;0.0236; p\u0026thinsp;\u0026gt;\u0026thinsp;0.05), and no sex-related differences were observed. Likewise, CT-VHS showed no significant differences between males (10.39\u0026thinsp;\u0026plusmn;\u0026thinsp;0.32) and females (10.34\u0026thinsp;\u0026plusmn;\u0026thinsp;0.42) and did not correlate with age (r = \u0026minus;\u0026thinsp;0.0236; p\u0026thinsp;\u0026gt;\u0026thinsp;0.05) or body weight (r\u0026thinsp;=\u0026thinsp;0.0387; p\u0026thinsp;\u0026gt;\u0026thinsp;0.05). These findings confirm that VHS is a relatively stable parameter that is not substantially influenced by basic physical characteristics.\u003c/p\u003e \u003cp\u003eDifferences between our results and those of Yaramış et al. may be explained by several factors. Their study included dogs of various breeds with diverse body conformations and thoracic shapes, which influence cardiac orientation and silhouette geometry. In contrast, our study focused on a single breed with uniform body structure, which is advantageous because it eliminates interbreed differences and reduces morphological variability.\u003c/p\u003e \u003cp\u003eThe main limitations of this study include the relatively small sample size, particularly for CT measurements, which may limit the statistical power of some comparisons. Additionally, all measurements were performed by a single evaluator; while this ensured methodological consistency and eliminated inter-observer variability, it did not allow assessment of reproducibility among different observers. Nevertheless, all measurements were performed under standardized technical conditions and according to a unified protocol, and the risk of systematic measurement error was minimized.\u003c/p\u003e \u003cp\u003eThe findings of this study confirm that both radiography and CT provide reliable information about cardiac silhouette size in the Tatra hound. The reference values established here may serve as a basis for clinical interpretation in healthy individuals of this breed and contribute to more accurate assessment of potential cardiomegaly in future clinical cases.\u003c/p\u003e \u003cp\u003eFuture research should include a larger population, including dogs with various cardiovascular diseases, to better evaluate the diagnostic value of CT in distinguishing physiological from pathological changes in cardiac size. Additional studies involving multiple evaluators would also be beneficial to assess reproducibility and inter-observer variability of VHS measurements.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eOur study provides the first reference values for the vertebral heart score (VHS) in the Tatra hound and compares measurements obtained from radiography and computed tomography. The results demonstrate that both imaging modalities offer consistent assessments of cardiac silhouette size in clinically healthy individuals. The mean VHS values were slightly higher than the commonly cited reference ranges for dogs, indicating breed-specific differences related to thoracic shape and proportions. These findings highlight the importance of using breed-specific reference values when evaluating cardiac size. The established data may improve the accuracy of both radiographic and CT-based diagnostics and support the early identification of pathological changes in the cardiac silhouette in the Tatra hound.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eCT \u0026ndash; computed tomography\u003c/p\u003e\n\u003cp\u003eVHS \u0026ndash; vertebral heart score\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis publication was supported by the Internal Grant Agency of the University of Veterinary Medicine and Pharmacy in Košice (IGA UVLF 08/2025: \u003cem\u003eRadiological study of the thoracic cavity in the Slovak national dog breed Tatra hound\u003c/em\u003e). The authors thank all participating dog owners for their cooperation.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was funded by the Internal Grant Agency of the University of Veterinary Medicine and Pharmacy in Košice (IGA UVLF 08/2025).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Information\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAuthors and Affiliations\u003c/p\u003e\n\u003cp\u003eVeterinary Teaching Hospital, University of Veterinary Medicine and Pharmacy in Košice, Košice, Slovak Republic\u003c/p\u003e\n\u003cp\u003eG. Kacková,\u0026nbsp;M. Figurová, Vargová,\u0026nbsp;Ľ. Horňáková, S. Horňák\u003c/p\u003e\n\u003cp\u003eSmall Animal Referral Centre Sibra, AniCura, Bratislava, Slovak Republic\u003c/p\u003e\n\u003cp\u003eC. F. Agudelo\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eG.K. participated in study coordination, performed radiographic examinations, and prepared the manuscript.\u003cbr\u003e\u0026nbsp;M.F. performed CT examinations and contributed to methodological design.\u003cbr\u003e\u0026nbsp;C.F.A. conducted clinical assessments including echocardiographic and electrocardiographic examinations.\u003cbr\u003e\u0026nbsp;N.V. coordinated the acquisition and recruitment of study animals.\u003cbr\u003e\u0026nbsp;S.H. designed the study, performed statistical analyses, interpreted the data, and critically revised the manuscript. L.H. was responsible for the statistical analysis and interpretation of the data.\u003cbr\u003e\u0026nbsp;All authors have read and approved the final version of the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCorresponding author\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eCorrespondence to S. Hornak.\u003c/p\u003e\n\u003cp\u003eEthical approval and consent to participate\u003c/p\u003e\n\u003cp\u003eThe study was approved by the Ethics Committee of the University of Veterinary Medicine and Pharmacy in Košice (approval number: EKVP/2023-20). Written informed consent for participation was obtained from all dog owners.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWritten informed consent from the dog’s owner was obtained for the publication.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets generated and analyzed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eLamb CR, Tyler M, Boswood A, Skelly BJ, Cain M. Assessment of the value of the vertebral heart scale in the radiographic diagnosis of cardiac disease in dogs. Vet Rec. 2000;146:687–90. doi: 10.1136/vr.146.24.687.\u003c/li\u003e\n\u003cli\u003eBuchanan JW, Bücheler J. Vertebral scale system to measure canine heart size in radiographs. J Am Vet Med Assoc. 1995;206:194–9.\u003c/li\u003e\n\u003cli\u003eLamb CR, Wikeley H, Boswood A, Pfeiffer DU. Use of breed‐specific ranges for the vertebral heart scale as an aid to the radiographic diagnosis of cardiac disease in dogs. Vet Rec. 2001;148:707–11. doi: 10.1136/vr.148.23.707.\u003c/li\u003e\n\u003cli\u003eWoolley R, Smith P, Munro E, Smith S, Swift S, Devine C, et al. Effects of treatment type on vertebral heart size in dogs with myxomatous mitral valve disease. Vet Rec. 2007;161:684–688.\u003c/li\u003e\n\u003cli\u003eKallassy A, Calendrier E, Bouhsina N, Fusellier M. Vertebral heart scale for the brittany spaniel: breed-specific range and its correlation with heart disease assessed by clinical and echocardiographic findings. Vet Sci. 2021;8:300. doi: 10.3390/vetsci8120300.\u003c/li\u003e\n\u003cli\u003eGuglielmini C, Diana A, Santarelli G, Torbidone A, Di Tommaso M, Toaldo MB, et al. Accuracy of radiographic vertebral heart score and sphericity index in the detection of pericardial effusion in dogs. J Am Vet Med Assoc.2012;241:1048–55.\u003c/li\u003e\n\u003cli\u003eGugjoo MB, Hoque M, Saxena AC, Zama MMS. Vertebral Scale System to Measure Heart Size in Dogs in Thoracic Radiographs. Adv Anim Vet Sci. 2013.\u003c/li\u003e\n\u003cli\u003eParmar SM, Patel MD, Vala JA, Mehta SA, Mavadiya SV. Clinical features and incidence of dilated cardiomyopathy in dogs of South Gujarat, India. IJAH. 2022;Online. doi: 10.36062/ijah.2022.04222.\u003c/li\u003e\n\u003cli\u003eNakayama H, Nakayama T, Hamlinxya RL. Correlation of Cardiac Enlargement as Assessed by Vertebral Heart Size and Echocardiographic and Electrocardiographic Findings in Dogs with Evolving Cardiomegaly Due to Rapid Ventricular Pacing. J Vet Intern Med. 2001;15:217–21. doi: 10.1111/j.1939-1676.2001.tb02314.x.\u003c/li\u003e\n\u003cli\u003eJepsen-Grant K, Pollard R e., Johnson L r. Vertebral Heart Scores in Eight Dog Breeds. Vet Radiol Ultrasound. 2013;54:3–8. doi: 10.1111/j.1740-8261.2012.01976.x.\u003c/li\u003e\n\u003cli\u003eWiegel PS, Mach R, Nolte I, Freise F, Levicar C, Merhof K, et al. Breed-specific values for vertebral heart score (VHS), vertebral left atrial size (VLAS), and radiographic left atrial dimension (RLAD) in pugs without cardiac disease, and their relationship to Brachycephalic Obstructive Airway Syndrome (BOAS). PLoS One. 2022;17:e0274085. doi: 10.1371/journal.pone.0274085.\u003c/li\u003e\n\u003cli\u003eNa H, Lee Y, Lee S-K, Choi H, Lee Y, Lee K. The breed-specific vertebral heart score and vertebral left atrial size in toy breed dogs. Thai J Vet Med. 2022;52. doi: 10.14456/tjvm.2022.87.\u003c/li\u003e\n\u003cli\u003eLuciani MG, Withoeft JA, Mondardo Cardoso Pissetti H, Pasini De Souza L, Silvestre Sombrio M, Bach EC, et al. Vertebral heart size in healthy Australian cattle dog. Anat Histol Embryol. 2019;48:264–7. doi: 10.1111/ahe.12434.\u003c/li\u003e\n\u003cli\u003eTaylor CJ, Simon BT, Stanley BJ, Lai GP, Thieman Mankin KM. Norwich terriers possess a greater vertebral heart scale than the canine reference value. Vet Radiol Ultrasound. 2020;61:10–5. doi: 10.1111/vru.12813.\u003c/li\u003e\n\u003cli\u003eSlovak Kennel Club. Standard of the Tatra hound. https://tatranskyduric.sk/tatransky-duric/standard-tatranskeho-durica/. Accessed 13 Nov 2025.\u003c/li\u003e\n\u003cli\u003eTimperman L, Habing G, Green E. The vertebral heart scale on CT is correlated to radiographs in dogs. Vet Radiol Ultrasound. 2021;62:519–24. doi: 10.1111/vru.12976.\u003c/li\u003e\n\u003cli\u003eNabi SU, Wani AR, Dey S. Radiographic measurements (vertebral heart scale) of popular breeds of dogs in India. Appl Biol Res. 2014;16:242–6.\u003c/li\u003e\n\u003cli\u003eShakya SK. Vertebral scale system to measure heart size in thoracic radiographs of Labrador retriever dogs. Indian Vet J. 2013;90:71–3.\u003c/li\u003e\n\u003cli\u003eBodh D, Hoque M, Saxena AC, Gugjoo MB, Bist D, Chaudhary JK. Vertebral scale system to measure heart size in thoracic radiographs of Indian Spitz, Labrador retriever and Mongrel dogs. Vet World. 2016;9:371. doi: 10.14202/vetworld.2016.371-376.\u003c/li\u003e\n\u003cli\u003eNeagu AG, Tudor N, Vlăgioiu C. Vertebral heart scores in four dog breeds. Lucrări Științifice-Medicină Veterinară, Universitatea de Științe Agricole și Medicină Veterinară\" Ion Ionescu de la Brad\" Iași. 2014;57:61–4.\u003c/li\u003e\n\u003cli\u003eBagardi M, Locatelli C, Manfredi M, Bassi J, Spediacci C, Ghilardi S, et al. Breed‐specific vertebral heart score, vertebral left atrial size, and radiographic left atrial dimension in Cavalier King Charles Spaniels: Reference interval study. Vet Radiol Ultrasound. 2022;63:156–63. doi: 10.1111/vru.13036.\u003c/li\u003e\n\u003cli\u003eMarin LM, Brown J, McBRIEN C, Baumwart R, Samii VF, Couto CG. VERTEBRAL HEART SIZE IN RETIRED RACING GREYHOUNDS. Vet Radiol Ultrasound. 2007;48:332–4. doi: 10.1111/j.1740-8261.2007.00252.x.\u003c/li\u003e\n\u003cli\u003eBhargavi S, Kannan TA, Ramesh G, Sumathi D, Prasad AA. Radiographic evaluation of heart using VHS method in Rajapalayam dog-indigenous breed of Tamil Nadu. Int J Curr Microbiol App Sci. 2019;8:1216–20. doi: 10.20546/ijcmas.2019.802.141.\u003c/li\u003e\n\u003cli\u003eSzpinda O, Parzeniecka-Jaworska M, Czopowicz M, Jońska I, Bonecka J, Jank M. Cardiological Reference Intervals in Adult American Staffordshire Terrier Dogs. Animals. 2023;13:2436. doi: 10.3390/ani13152436.\u003c/li\u003e\n\u003cli\u003eSoeratanapant S. Reliability of cardiac measurement by vertebral heart score among different thoracic types of dogs. Chulalongkorn University Theses and Dissertations (Chula ETD). 2023.doi: 10.58837/CHULA.THE.2023.1069.\u003c/li\u003e\n\u003cli\u003eColina CV, do Imperador B de G. Vertebral heart size in healthy Belgian Malinois dogs. J Vet Adv. 2015;5:1176–80. doi: 10.5455/jva.20151214094007.\u003c/li\u003e\n\u003cli\u003eYaramış ÇP, Erdikmen DO, Altundağ Y, Özkan E, Güzel BC. Examination of the vertebral heart scale and anatomical structure of different dog breeds by computed tomography. Kafkas Univ Vet Fak Derg. 2024;30(3):305–310. doi:10.9775/kvfd.2023.30599.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"vertebral heart score, thoracic radiography, computed tomography, breed-specific reference values, Tatra hound, healthy dogs","lastPublishedDoi":"10.21203/rs.3.rs-8552310/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8552310/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground: \u003c/strong\u003eThe vertebral heart score (VHS) is widely used to assess cardiac silhouette size in dogs, but breed-specific reference values are needed to improve diagnostic accuracy. No radiographic or computed tomographic (CT) VHS reference values have been established for the Tatra hound. This study aimed to determine breed-specific radiographic and CT VHS values in clinically healthy Tatra hound dogs, evaluate the influence of sex, age, and body weight, and assess the agreement and correlation between VHS measurements obtained from radiography and CT.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults: \u003c/strong\u003eThe mean RTG-VHS was 10.54 ± 0.51 (n = 43) and the mean CT-VHS was 10.36 ± 0.44 (n = 25), with no significant difference between the two modalities (paired t-test, p = 0.0576). No significant correlation was found between RTG-VHS and CT-VHS (r = –0.039). No sex-related differences were detected for either method, and VHS did not correlate with age or body weight.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions: \u003c/strong\u003eRadiographic and CT VHS values in healthy Tatra hound dogs show close agreement and no systematic difference, but the absence of a linear correlation indicates that individual RTG and CT measurements are not directly interchangeable. These results establish the first modality-specific VHS reference intervals for this breed and support the clinical use of VHS in Tatra hounds.\u003c/p\u003e","manuscriptTitle":"Evaluation of Radiographic and Computed Tomographic Vertebral Heart Score in Healthy Tatra hound breed","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-01-26 17:39:27","doi":"10.21203/rs.3.rs-8552310/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"f63be1d2-1ce1-4f03-b58f-90b57aab1922","owner":[],"postedDate":"January 26th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-01-30T11:42:03+00:00","versionOfRecord":[],"versionCreatedAt":"2026-01-26 17:39:27","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8552310","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8552310","identity":"rs-8552310","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}