Evaluation of Eye, Udder, and Vulvar Surface Temperatures Combined with Serum Progesterone for Detecting Parturition Time in Goats

Evaluation of Eye, Udder, and Vulvar Surface Temperatures Combined with Serum Progesterone for Detecting Parturition Time in Goats | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Evaluation of Eye, Udder, and Vulvar Surface Temperatures Combined with Serum Progesterone for Detecting Parturition Time in Goats atakan cortu, durmus kahraman This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7583725/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 This study aimed to investigate changes in surface temperatures of the eye, udder, and vulvar region in goats, alongside serum progesterone levels, to determine whether these parameters may collectively indicate impending parturition. Fifteen clinically healthy Honamli goats were synchronized for estrus and artificially inseminated. Serum samples were collected every 24 hours from 96 hours before to 24 hours after parturition for progesterone analysis. Infrared thermographic images were obtained every 6 hours from 11 anatomical sites: right and left cornea, right and left medial canthus, right and left lacrimal sac, right and left lateral udder, right and left caudal udder, and the vulvar region. Among these, only the lateral udder and vulvar temperatures were significantly associated with progesterone concentrations. Serum progesterone declined significantly as parturition approached (p < 0.001), with values at 96 and 72 hours before parturition significantly higher than those at parturition and 24 hours postpartum. Lateral udder temperature showed a weak negative correlation with progesterone levels ( r s = -0.274, p = 0.009), whereas vulvar temperature showed a weak positive correlation ( r s = 0.311, p = 0.003). A significant temporal increase was observed only in lateral udder temperature (p = 0.026). No significant differences were found between animals delivering during the daytime and those delivering at night. In conclusion, combining surface temperature measurements from specific anatomical regions with serum progesterone levels may improve the accuracy of parturition prediction in goats. However, the relatively weak associations and regional variability indicate the need for further research before clinical implementation. Eye goat parturition progesterone thermography udder Figures Figure 1 Introduction Timely prediction of parturition in livestock plays a crucial role in reducing delivery-related complications, improving reproductive efficiency, and ensuring neonatal survival (Mee 2008 ). Early detection of labor onset is particularly important for managing dystocia, a condition that occurs in approximately 9.7–16.8% of ewes and poses significant risks to both the dam and the offspring if left unattended during birth (Nabenishi and Yamazaki 2017 ). A consistent physiological indicator of impending parturition is a decline in body temperature, which reflects the regression of the corpus luteum and the associated reduction in progesterone secretion (Burfeind et al. 2011 ). This temperature drop has been reported in multiple species, including cattle, sheep, and buffaloes (Aoki et al. 2005 ; Ouellet et al. 2016 ). However, while rectal and vaginal thermometry effectively capture this change, their invasiveness limits their use in routine animal management (Koyama et al. 2018 ). Infrared thermography (IRT) has emerged as a non-invasive tool for monitoring physiological changes through surface temperature evaluation and has been used in the assessment of estrus, stress, udder health, and metabolic conditions (Korelidou et al. 2025 ; Schaefer et al. 2025 ). The temperature measurements of the eye and udder using IRT have proven valuable for detecting subclinical mastitis and related udder alterations in dairy animals (Berry et al. 2003 ; Colak et al. 2008 ; Polat et al. 2010 ). A recent study in buffaloes has demonstrated that vulvar and udder skin temperatures, measured by IRT, begin to decline approximately 48 hours prior to calving in parallel with reductions in plasma progesterone levels (Teja et al. 2025 ). These changes are followed by a slight increase just before parturition and are reported to be largely unaffected by circadian variation (Sakthivel et al. 2023). Although earlier studies have documented a moderate correlation (r = 0.62) between core and surface temperatures in ewes (Nabenishi and Yamazaki 2017 ), and the usefulness of IRT for udder health evaluation in goats has been established (Korelidou et al. 2025 ), to our knowledge, no research to date has integrated thermographic data with concurrent serum progesterone measurements for predicting parturition in goats. Therefore, the present study aimed to assess whether changes in the surface temperatures of the eye, udder, and vulvar region, together with serum progesterone levels, could serve as combined indicators of impending parturition in goats. We hypothesized that surface temperatures of the ocular, udder, and vulvar regions, as measured by infrared thermography, would show a significant temporal decline preceding parturition and that these changes would be positively correlated with serum progesterone concentrations, thereby serving as reliable, non-invasive indicators of impending labor in goats. Materials and Methods Animals and housing conditions The study was conducted in June 2025 and involved 15 Honamli goats that were clinically healthy. The animals, ranging in age from 2 to 5 years and having previously undergone at least one parturition, were housed in a semi-open shelter that allowed exposure to natural light and ambient temperature throughout the breeding season. Their daily diet consisted of 0.5 kg barley flakes, 100 g milk feed, and 2 kg dried sainfoin hay. Water was available without restriction. Animals were selected based on health status, age, reproductive history, and breed characteristics. Those that exhibited systemic illness, failed to conceive following artificial insemination, or required intervention during delivery were excluded from the study. Estrus synchronization and pregnancy confirmation To induce estrus, an intravaginal sponge containing 60 mg of medroxyprogesterone acetate (Esponjavet®, Hipra, Spain) was inserted using a sterilized applicator and left in place for six days. The applicator was rinsed with warm water and soaked in a 0.1–0.2% chlorhexidine solution for one minute between uses to maintain hygiene. Upon sponge removal, each goat received intramuscular injections of 400 IU equine chorionic gonadotropin (Oviser®, Hipra, Spain) and 75 µg cloprostenol (Dalmazin®, Vetas, Türkiye). Artificial insemination was performed using freshly collected semen at 48 and 60 hours after sponge withdrawal. Blood sampling and hormone analysis Jugular blood samples were obtained every 24 hours beginning 96 hours before the estimated parturition time and continuing until 24 hours after birth. According to the sampling schedule, six progesterone measurements were performed at 24-hour intervals, specifically at T1 (-96 h), T5 (-72 h), T9 (-48 h), T13 (-24 h), T17 (0 h, parturition), and T21 (+ 24 h). Samples were collected into serum separator tubes, stored on ice, and centrifuged within one hour at 2500 x g for 15 minutes at 5°C. The serum was separated, aliquoted, and stored at -20°C until progesterone levels were analyzed. Quantification was performed using a commercial enzyme-linked immunosorbent assay (ELISA) kit (DRG International, Progesterone ELISA Kit, Catalog No: EIA-1561, Germany), following the manufacturer’s instructions. Absorbance readings were taken at 450 nm with a microplate reader (ELx800, Biotek Instruments, USA), and hormone concentrations were calculated from a standard calibration curve. Infrared thermographic imaging Infrared thermal images were obtained every 6 hours from each goat, starting 96 hours before parturition and continuing until 24 hours postpartum. Accordingly, a total of 21 thermographic measurements were taken at 6-hour intervals, corresponding to timepoints T1 (-96 h) through T21 (+ 24 h), including the exact time of parturition (T17 = 0 h). The precise timing of birth was determined via 24-hour surveillance camera footage and confirmed by trained personnel present at the facility. Goats that delivered between 06:00 and 19:59 were classified under the daytime group to reflect the natural light-dark cycle, which may influence parturition-related physiological responses, whereas those that delivered between 20:00 and 05:59 were placed in the nighttime group. A handheld thermal imaging device (Fluke TiS55+, Fluke Corporation, USA) was used for all measurements. The camera operated in the 8–14 µm infrared spectrum, with a spatial resolution of 256 x 192 pixels, a temperature detection range of -20 to 550°C, and an accuracy of ± 2%. The emissivity setting was fixed at 0.98. Prior to imaging, any visible debris or moisture was removed from the skin surface using a clean, dry cloth to minimize artifacts. Thermal measurements were obtained from eleven anatomical regions: the right and left cornea, right and left medial canthus, right and left lacrimal sac, right and left lateral udder, right and left caudal udder, and the vulvar region (Fig. 1 ). For final analysis, only the thermal images and serum samples obtained between − 96 and + 24 hours relative to parturition were included. To evaluate hormone-temperature relationships, surface temperatures measured at the timepoints matching the progesterone sampling intervals (every 24 h) were used. Statistical analysis In the preliminary phase, right and left anatomical regions were compared to assess potential lateral asymmetry in surface temperature. Paired comparisons were performed for the cornea, medial canthus, lacrimal sac, and both the lateral and caudal surfaces of the udder using either paired t-tests or Wilcoxon signed-rank tests, depending on the distribution of the data. A statistically significant difference was detected between right and left corneal temperatures (p 0.05 for all). Therefore, left and right measurements were averaged for subsequent analysis, except for the cornea. The normality of continuous variables was evaluated using the Shapiro-Wilk test. None of the temperature variables followed a normal distribution; therefore, temporal changes across the six predefined timepoints (-96 h to + 24 h) were assessed using the Friedman test. Comparisons between daytime and nighttime parturition groups were performed using the Mann-Whitney U test. Relationships between serum progesterone concentrations and surface temperatures were examined using Spearman’s rank correlation ( r s ) coefficient. A p-value less than 0.05 was considered statistically significant. All analyses were conducted using IBM SPSS Statistics version 25.0 (IBM Corp., Armonk, NY, USA). Results A total of 8 animals were classified in the daytime group and 7 in the nighttime group, yielding 168 and 147 thermographic observations, respectively. Serum progesterone concentrations measured at six timepoints relative to parturition (-96 h, -72 h, -48 h, -24 h, 0 h, and + 24 h) showed a significant temporal decline (p < 0.001). Progesterone levels at -96 h and − 72 h were significantly higher than those at 0 h (p = 0.004 and 0.008, respectively) and + 24 h (p = 0.003 and 0.005, respectively) (Table 1 ). Table 1 Median (range) serum progesterone concentrations (ng/mL) in goats measured at six timepoints from 96 hours before to 24 hours after parturition. A significant temporal decline was observed (p < 0.001), with progesterone levels at -96 h and − 72 h being significantly higher than those at parturition (0 h; p = 0.004 and 0.008, respectively) and at 24 hours postpartum (+ 24 h; p = 0.003 and 0.005, respectively). Progesterone (ng/mL) Time points -96 h -72 h -48 h -24 h 0 h + 24 h 7.5 (6.5–9.1) 6.5 (5.0-7.8) 5.1 (3.2–6.6) 3.5 (2.0-5.5) 2.2 (1.4–3.3) 1.5 (0.9–2.5) A weak but statistically significant negative correlation was observed between serum progesterone concentrations and lateral udder surface temperature ( r s = -0.274, p = 0.009; 95% CI: -0.455 to -0.071). Conversely, a weak yet significant positive correlation was found between progesterone levels and vulvar temperature ( r s = 0.311, p = 0.003; 95% CI: 0.112 to 0.487). No significant correlations were identified between progesterone concentrations and the temperatures of the right cornea ( r s = 0.128, p = 0.229), left cornea ( r s = 0.001, p = 0.992), medial canthus ( r s = 0.054, p = 0.61), lacrimal sac ( r s = 0.150, p = 0.157), or caudal udder ( r s = -0.137, p = 0.197). The median surface temperature of the lateral udder region increased significantly over time (p = 0.026), rising from 35.0°C (33.0-37.3°C) at -96 h to 36.0°C (33.6–37.5°C) at + 24 h. In contrast, no significant temporal variations were observed in the surface temperatures of the right cornea (p = 0.852), left cornea (p = 0.328), medial canthus (p = 0.294), lacrimal sac (p = 0.124), caudal udder (p = 0.392), or vulva (p = 0.092) (Table 2 ). No significant differences were detected between animals delivering during the daytime and those delivering at night at any measured timepoint (p > 0.05). Table 2 Temporal changes in median (range) surface temperatures (°C) of seven anatomical regions at six timepoints from 96 hours before (-96 h) to 24 hours after parturition (+ 24 h) in goats. Region Time p-value -96 h -72 h -48 h -24 h 0 h + 24 h Right Cornea 34.90 (34.10–36.20) 34.80 (33.50–37.00) 34.70 (33.10–36.50) 35.00 (33.50–35.80) 34.90 (34.00-35.70) 34.80 (34.00-36.20) 0.852 Left Cornea 35.00 (33.90–36.30) 34.70 (33.60–36.50) 34.60 (33.40–36.00) 35.00 (34.00-36.50) 34.80 (33.30–35.60) 35.00 (33.50–37.30) 0.328 Medial Canthus 36.00 (34.00–37.00) 36.00 (33.70–37.50) 35.10 (33.80–37.30) 36.00 (34.20–37.40) 36.00 (33.50–36.90) 36.00 (34.20–36.50) 0.294 Lacrimal Sac 35.90 (34.10–37.30) 36.00 (33.70–37.50) 35.70 (34.20–36.30) 36.00 (35.10–36.90) 35.20 (34.00-36.50) 35.80 (33.70–36.50) 0.124 Lateral Udder 35.00 (33.00-37.30) 35.00 (34.00-36.50) 34.80 (32.00-36.20) 35.90 (33.50–36.60) 35.80 (34.00-37.80) 36.00 (33.60–37.50) 0.026* Caudal Udder 34.80 (34.10–35.60) 35.00 (32.50–36.50) 34.70 (33.90–36.30) 34.70 (33.80–36.10) 35.00 (33.90–37.00) 35.00 (34.00-36.30) 0.392 Vulva 34.50 (32.00-35.60) 34.00 (31.20–36.00) 34.00 (31.00-35.60) 33.90 (31.60–35.60) 32.80 (31.00-34.50) 34.00 (32.50–35.00) 0.092 Discussion The main finding of the present study was that, despite a marked decline in serum progesterone concentrations during the final 96 hours before parturition, thermal responses varied by anatomical site and were not consistently aligned with hormonal changes. A significant increase in the lateral udder surface temperature was the most notable thermographic observation, whereas vulvar and ocular temperatures did not demonstrate significant temporal variation. These results partially support the initial hypothesis that surface temperatures in the ocular, udder, and vulvar regions would decrease in line with progesterone decline and serve as reliable, non-invasive indicators of impending parturition. The gradual elevation in lateral udder temperature may be explained by increased mammary perfusion and metabolic activity associated with the onset of colostrum synthesis, rather than being a direct reflection of systemic hormonal withdrawal. Previous work in ewes demonstrated a progressive decline in body surface temperature measured at the upper neck prior to lambing, which was interpreted as a result of reduced metabolic heat production following luteolysis and progesterone decline (Nabenishi and Yamazaki 2017 ). General body surface sites tend to reflect systemic thermoregulatory changes, whereas the mammary gland is influenced by localized functional activity related to the onset of lactation. These region-specific dynamics may explain the distinct temperature increases observed in the udder during the prepartum period (Teja et al. 2023 ). The positive correlation between vulvar surface temperature and progesterone, although statistically significant, was weak and not in line with physiological expectations. Some studies have reported a drop in perineal temperature before parturition, often linked to hormonal effects on blood flow (Mincu et al. 2023 ; de Ruediger et al. 2018 ). Another study has described a pattern where vulvar temperature first decreases, then rises again shortly before calving (Teja et al. 2025 ). The slight temperature decrease observed in this study may be related to the hormonal activity. The lack of temperature change in the ocular and periorbital regions is consistent with earlier studies showing that these areas are not particularly responsive to reproductive hormonal fluctuations (Suthar et al. 2011; Martello et al. 2016). Strong autonomic regulation in these areas likely minimises thermal fluctuations, when focused on sites with greater hormonal or metabolic responsiveness. The absence of differences between animals giving birth during daytime and nighttime further supports the robustness of the thermal data, as some previous observations had identified circadian effects in body temperature rhythms prior to parturition (Nabenishi and Yamazaki 2017 ). However, a report also exists showing that circadian patterns become less distinct as parturition approaches, possibly due to overriding hormonal or behavioral drivers (Teja et al. 2025 ). The current findings align more closely with those studies and suggest that time of day does not significantly influence surface temperature changes in the final phase of gestation. This study had several limitations. First, the relatively small sample size may have limited the statistical power to detect subtle thermal changes, particularly in regions with high individual variability. Second, although environmental conditions were monitored, minor fluctuations in ambient temperature or humidity could still have influenced surface temperature measurements. Third, thermal imaging was performed at fixed time intervals, which may have missed transient changes occurring between observations. Finally, progesterone was the only hormonal parameter assessed; evaluating additional reproductive hormones could provide a more complete understanding of prepartum thermal dynamics. Conclusion Serum progesterone levels declined consistently in the days preceding parturition, yet thermal responses differed across regions, with the lateral udder showing the clearest change. Combining thermographic data with hormonal measurements appears to offer greater reliability for predicting parturition than using thermography alone, with the lateral udder and vulvar regions showing the highest potential value when integrated with endocrine information. However, the moderate strength of these associations underlines the need for further research to refine and validate thermographic approaches for broader application. Declarations Acknowledgements We would like to thank Burdur MAKÜ Agriculture, Livestock and Food Research Application and Research Center for allowing us to conduct this study on the animals in its farm. Author contributions Cortu A prepared the original draft of the manuscript, designed the study methodology, administered the project, and performed the investigation, formal analysis, and data curation. He also contributed to the conceptualization and visualization of the study and revised and edited the manuscript text. Kahraman D contributed to data curation, investigation, and visualization, and participated in revising and editing the manuscript text. All authors reviewed and edited all versions of the manuscript. All authors read and approved the final manuscript. Funding This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Data Availability The data supporting the findings of this study are available in the: https://figshare.com/s/6eb10b9323fefb196110 Statement of Animal Ethics This study was approved by the Burdur Mehmet Akif Ersoy University Animal Experiments Local Ethics Committee (Approval No: 2025/1502). All procedures involving animals were conducted in compliance with national regulations governing the ethical treatment and use of experimental animals. Conflict of Interest Statement None of the authors has any other financial or personal relationships that could inappropriately influence or bias the content of the paper. References Aoki M, Kimura K, Suzuki O (2005). Predicting time of parturition from changing vaginal temperature measured by data-logging apparatus in beef cows with twin fetuses. Anim Reprod Sci 86(1-2):1–12. https://doi.org/10.1016/j.anireprosci.2004.04.046 Berry RJ, Kennedy AD, Scott SL, Kyle BL, Schaefer AL (2003). 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Teja A, Sakthivel J, Rao KA, Krishnaswamy N, Chintalapati GV, Veerappa VG, Kumaresan A, Ramesha KP, Sivaram M, Kataktalware MA, Das DN, Mula RK, Lavanya M (2025). Thermal signatures of vulval skin surface: a potential non-invasive diagnostic technology to monitor the calving process in water buffalo (Bubalus bubalis). Reprod Domest Anim 60(5):e70065. https://10.1111/rda.70065. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7583725","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":517225973,"identity":"9ab466f9-0282-4fd9-8fe7-b294e70fcbcf","order_by":0,"name":"atakan 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07:05:10","extension":"xml","order_by":5,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":66143,"visible":true,"origin":"","legend":"","description":"","filename":"f4613cf521f347159cfd762558b7a21d1structuring.xml","url":"https://assets-eu.researchsquare.com/files/rs-7583725/v1/f6b64c260443c4a87576d8d2.xml"},{"id":91953906,"identity":"d974f833-10f5-4bc8-a5eb-358d704b42b8","added_by":"auto","created_at":"2025-09-23 07:05:11","extension":"html","order_by":6,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":70766,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-7583725/v1/de0a79ab1ab10cf1d104160a.html"},{"id":91956370,"identity":"5601b2c1-4d97-4117-9fa3-1fa4a8cc3a0e","added_by":"auto","created_at":"2025-09-23 07:13:10","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":460420,"visible":true,"origin":"","legend":"\u003cp\u003eRepresentative infrared thermographic images illustrating the anatomical regions evaluated in the study: A. Ocular surface regions, B. Lateral udder, C. Caudal udder, D. Vulvar region.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-7583725/v1/97484cf9b5b84e9f2a4f0b0e.png"},{"id":92307737,"identity":"e0c081a9-26ce-4263-acc1-f95dbf9d7eb0","added_by":"auto","created_at":"2025-09-27 08:32:00","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1053474,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7583725/v1/97e712f3-4869-4254-ac78-b450b5696d2e.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Evaluation of Eye, Udder, and Vulvar Surface Temperatures Combined with Serum Progesterone for Detecting Parturition Time in Goats","fulltext":[{"header":"Introduction","content":"\u003cp\u003eTimely prediction of parturition in livestock plays a crucial role in reducing delivery-related complications, improving reproductive efficiency, and ensuring neonatal survival (Mee \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2008\u003c/span\u003e). Early detection of labor onset is particularly important for managing dystocia, a condition that occurs in approximately 9.7\u0026ndash;16.8% of ewes and poses significant risks to both the dam and the offspring if left unattended during birth (Nabenishi and Yamazaki \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). A consistent physiological indicator of impending parturition is a decline in body temperature, which reflects the regression of the corpus luteum and the associated reduction in progesterone secretion (Burfeind et al. \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2011\u003c/span\u003e). This temperature drop has been reported in multiple species, including cattle, sheep, and buffaloes (Aoki et al. \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2005\u003c/span\u003e; Ouellet et al. \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2016\u003c/span\u003e). However, while rectal and vaginal thermometry effectively capture this change, their invasiveness limits their use in routine animal management (Koyama et al. \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2018\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eInfrared thermography (IRT) has emerged as a non-invasive tool for monitoring physiological changes through surface temperature evaluation and has been used in the assessment of estrus, stress, udder health, and metabolic conditions (Korelidou et al. \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2025\u003c/span\u003e; Schaefer et al. \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). The temperature measurements of the eye and udder using IRT have proven valuable for detecting subclinical mastitis and related udder alterations in dairy animals (Berry et al. \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2003\u003c/span\u003e; Colak et al. \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2008\u003c/span\u003e; Polat et al. \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2010\u003c/span\u003e). A recent study in buffaloes has demonstrated that vulvar and udder skin temperatures, measured by IRT, begin to decline approximately 48 hours prior to calving in parallel with reductions in plasma progesterone levels (Teja et al. \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). These changes are followed by a slight increase just before parturition and are reported to be largely unaffected by circadian variation (Sakthivel et al. 2023).\u003c/p\u003e\u003cp\u003eAlthough earlier studies have documented a moderate correlation (r\u0026thinsp;=\u0026thinsp;0.62) between core and surface temperatures in ewes (Nabenishi and Yamazaki \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2017\u003c/span\u003e), and the usefulness of IRT for udder health evaluation in goats has been established (Korelidou et al. \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2025\u003c/span\u003e), to our knowledge, no research to date has integrated thermographic data with concurrent serum progesterone measurements for predicting parturition in goats. Therefore, the present study aimed to assess whether changes in the surface temperatures of the eye, udder, and vulvar region, together with serum progesterone levels, could serve as combined indicators of impending parturition in goats. We hypothesized that surface temperatures of the ocular, udder, and vulvar regions, as measured by infrared thermography, would show a significant temporal decline preceding parturition and that these changes would be positively correlated with serum progesterone concentrations, thereby serving as reliable, non-invasive indicators of impending labor in goats.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003eAnimals and housing conditions\u003c/h2\u003e\u003cp\u003eThe study was conducted in June 2025 and involved 15 Honamli goats that were clinically healthy. The animals, ranging in age from 2 to 5 years and having previously undergone at least one parturition, were housed in a semi-open shelter that allowed exposure to natural light and ambient temperature throughout the breeding season. Their daily diet consisted of 0.5 kg barley flakes, 100 g milk feed, and 2 kg dried sainfoin hay. Water was available without restriction. Animals were selected based on health status, age, reproductive history, and breed characteristics. Those that exhibited systemic illness, failed to conceive following artificial insemination, or required intervention during delivery were excluded from the study.\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eEstrus synchronization and pregnancy confirmation\u003c/h3\u003e\n\u003cp\u003eTo induce estrus, an intravaginal sponge containing 60 mg of medroxyprogesterone acetate (Esponjavet\u0026reg;, Hipra, Spain) was inserted using a sterilized applicator and left in place for six days. The applicator was rinsed with warm water and soaked in a 0.1\u0026ndash;0.2% chlorhexidine solution for one minute between uses to maintain hygiene. Upon sponge removal, each goat received intramuscular injections of 400 IU equine chorionic gonadotropin (Oviser\u0026reg;, Hipra, Spain) and 75 \u0026micro;g cloprostenol (Dalmazin\u0026reg;, Vetas, T\u0026uuml;rkiye). Artificial insemination was performed using freshly collected semen at 48 and 60 hours after sponge withdrawal.\u003c/p\u003e\n\u003ch3\u003eBlood sampling and hormone analysis\u003c/h3\u003e\n\u003cp\u003eJugular blood samples were obtained every 24 hours beginning 96 hours before the estimated parturition time and continuing until 24 hours after birth. According to the sampling schedule, six progesterone measurements were performed at 24-hour intervals, specifically at T1 (-96 h), T5 (-72 h), T9 (-48 h), T13 (-24 h), T17 (0 h, parturition), and T21 (+\u0026thinsp;24 h). Samples were collected into serum separator tubes, stored on ice, and centrifuged within one hour at 2500 x g for 15 minutes at 5\u0026deg;C. The serum was separated, aliquoted, and stored at -20\u0026deg;C until progesterone levels were analyzed. Quantification was performed using a commercial enzyme-linked immunosorbent assay (ELISA) kit (DRG International, Progesterone ELISA Kit, Catalog No: EIA-1561, Germany), following the manufacturer\u0026rsquo;s instructions. Absorbance readings were taken at 450 nm with a microplate reader (ELx800, Biotek Instruments, USA), and hormone concentrations were calculated from a standard calibration curve.\u003c/p\u003e\n\u003ch3\u003eInfrared thermographic imaging\u003c/h3\u003e\n\u003cp\u003eInfrared thermal images were obtained every 6 hours from each goat, starting 96 hours before parturition and continuing until 24 hours postpartum. Accordingly, a total of 21 thermographic measurements were taken at 6-hour intervals, corresponding to timepoints T1 (-96 h) through T21 (+\u0026thinsp;24 h), including the exact time of parturition (T17\u0026thinsp;=\u0026thinsp;0 h). The precise timing of birth was determined via 24-hour surveillance camera footage and confirmed by trained personnel present at the facility. Goats that delivered between 06:00 and 19:59 were classified under the daytime group to reflect the natural light-dark cycle, which may influence parturition-related physiological responses, whereas those that delivered between 20:00 and 05:59 were placed in the nighttime group. A handheld thermal imaging device (Fluke TiS55+, Fluke Corporation, USA) was used for all measurements. The camera operated in the 8\u0026ndash;14 \u0026micro;m infrared spectrum, with a spatial resolution of 256 x 192 pixels, a temperature detection range of -20 to 550\u0026deg;C, and an accuracy of \u0026plusmn;\u0026thinsp;2%. The emissivity setting was fixed at 0.98. Prior to imaging, any visible debris or moisture was removed from the skin surface using a clean, dry cloth to minimize artifacts. Thermal measurements were obtained from eleven anatomical regions: the right and left cornea, right and left medial canthus, right and left lacrimal sac, right and left lateral udder, right and left caudal udder, and the vulvar region (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). For final analysis, only the thermal images and serum samples obtained between \u0026minus;\u0026thinsp;96 and +\u0026thinsp;24 hours relative to parturition were included. To evaluate hormone-temperature relationships, surface temperatures measured at the timepoints matching the progesterone sampling intervals (every 24 h) were used.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\u003ch2\u003eStatistical analysis\u003c/h2\u003e\u003cp\u003eIn the preliminary phase, right and left anatomical regions were compared to assess potential lateral asymmetry in surface temperature. Paired comparisons were performed for the cornea, medial canthus, lacrimal sac, and both the lateral and caudal surfaces of the udder using either paired t-tests or Wilcoxon signed-rank tests, depending on the distribution of the data. A statistically significant difference was detected between right and left corneal temperatures (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), while no significant differences were observed in the other regions (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05 for all). Therefore, left and right measurements were averaged for subsequent analysis, except for the cornea.\u003c/p\u003e\u003cp\u003eThe normality of continuous variables was evaluated using the Shapiro-Wilk test. None of the temperature variables followed a normal distribution; therefore, temporal changes across the six predefined timepoints (-96 h to +\u0026thinsp;24 h) were assessed using the Friedman test. Comparisons between daytime and nighttime parturition groups were performed using the Mann-Whitney U test. Relationships between serum progesterone concentrations and surface temperatures were examined using Spearman\u0026rsquo;s rank correlation (\u003cem\u003er\u003c/em\u003e\u003csub\u003e\u003cem\u003es\u003c/em\u003e\u003c/sub\u003e) coefficient. A p-value less than 0.05 was considered statistically significant. All analyses were conducted using IBM SPSS Statistics version 25.0 (IBM Corp., Armonk, NY, USA).\u003c/p\u003e\u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eA total of 8 animals were classified in the daytime group and 7 in the nighttime group, yielding 168 and 147 thermographic observations, respectively. Serum progesterone concentrations measured at six timepoints relative to parturition (-96 h, -72 h, -48 h, -24 h, 0 h, and +\u0026thinsp;24 h) showed a significant temporal decline (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Progesterone levels at -96 h and \u0026minus;\u0026thinsp;72 h were significantly higher than those at 0 h (p\u0026thinsp;=\u0026thinsp;0.004 and 0.008, respectively) and +\u0026thinsp;24 h (p\u0026thinsp;=\u0026thinsp;0.003 and 0.005, respectively) (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eMedian (range) serum progesterone concentrations (ng/mL) in goats measured at six timepoints from 96 hours before to 24 hours after parturition. A significant temporal decline was observed (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), with progesterone levels at -96 h and \u0026minus;\u0026thinsp;72 h being significantly higher than those at parturition (0 h; p\u0026thinsp;=\u0026thinsp;0.004 and 0.008, respectively) and at 24 hours postpartum (+\u0026thinsp;24 h; p\u0026thinsp;=\u0026thinsp;0.003 and 0.005, respectively).\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"7\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003eProgesterone (ng/mL)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colspan=\"6\" nameend=\"c7\" namest=\"c2\"\u003e\u003cp\u003eTime points\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e-96 h\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e-72 h\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-48 h\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e-24 h\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0 h\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e+\u0026thinsp;24 h\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e7.5\u003c/p\u003e\u003cp\u003e(6.5\u0026ndash;9.1)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e6.5\u003c/p\u003e\u003cp\u003e(5.0-7.8)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e5.1\u003c/p\u003e\u003cp\u003e(3.2\u0026ndash;6.6)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e3.5\u003c/p\u003e\u003cp\u003e(2.0-5.5)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e2.2\u003c/p\u003e\u003cp\u003e(1.4\u0026ndash;3.3)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e1.5\u003c/p\u003e\u003cp\u003e(0.9\u0026ndash;2.5)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eA weak but statistically significant negative correlation was observed between serum progesterone concentrations and lateral udder surface temperature (\u003cem\u003er\u003c/em\u003e\u003csub\u003e\u003cem\u003es\u003c/em\u003e\u003c/sub\u003e = -0.274, p\u0026thinsp;=\u0026thinsp;0.009; 95% CI: -0.455 to -0.071). Conversely, a weak yet significant positive correlation was found between progesterone levels and vulvar temperature (\u003cem\u003er\u003c/em\u003e\u003csub\u003e\u003cem\u003es\u003c/em\u003e\u003c/sub\u003e = 0.311, p\u0026thinsp;=\u0026thinsp;0.003; 95% CI: 0.112 to 0.487). No significant correlations were identified between progesterone concentrations and the temperatures of the right cornea (\u003cem\u003er\u003c/em\u003e\u003csub\u003e\u003cem\u003es\u003c/em\u003e\u003c/sub\u003e = 0.128, p\u0026thinsp;=\u0026thinsp;0.229), left cornea (\u003cem\u003er\u003c/em\u003e\u003csub\u003e\u003cem\u003es\u003c/em\u003e\u003c/sub\u003e = 0.001, p\u0026thinsp;=\u0026thinsp;0.992), medial canthus (\u003cem\u003er\u003c/em\u003e\u003csub\u003e\u003cem\u003es\u003c/em\u003e\u003c/sub\u003e = 0.054, p\u0026thinsp;=\u0026thinsp;0.61), lacrimal sac (\u003cem\u003er\u003c/em\u003e\u003csub\u003e\u003cem\u003es\u003c/em\u003e\u003c/sub\u003e = 0.150, p\u0026thinsp;=\u0026thinsp;0.157), or caudal udder (\u003cem\u003er\u003c/em\u003e\u003csub\u003e\u003cem\u003es\u003c/em\u003e\u003c/sub\u003e = -0.137, p\u0026thinsp;=\u0026thinsp;0.197).\u003c/p\u003e\u003cp\u003eThe median surface temperature of the lateral udder region increased significantly over time (p\u0026thinsp;=\u0026thinsp;0.026), rising from 35.0\u0026deg;C (33.0-37.3\u0026deg;C) at -96 h to 36.0\u0026deg;C (33.6\u0026ndash;37.5\u0026deg;C) at +\u0026thinsp;24 h. In contrast, no significant temporal variations were observed in the surface temperatures of the right cornea (p\u0026thinsp;=\u0026thinsp;0.852), left cornea (p\u0026thinsp;=\u0026thinsp;0.328), medial canthus (p\u0026thinsp;=\u0026thinsp;0.294), lacrimal sac (p\u0026thinsp;=\u0026thinsp;0.124), caudal udder (p\u0026thinsp;=\u0026thinsp;0.392), or vulva (p\u0026thinsp;=\u0026thinsp;0.092) (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). No significant differences were detected between animals delivering during the daytime and those delivering at night at any measured timepoint (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eTemporal changes in median (range) surface temperatures (\u0026deg;C) of seven anatomical regions at six timepoints from 96 hours before (-96 h) to 24 hours after parturition (+\u0026thinsp;24 h) in goats.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"8\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003eRegion\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"6\" nameend=\"c7\" namest=\"c2\"\u003e\u003cp\u003eTime\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003ep-value\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003e-96 h\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003e-72 h\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003e-48 h\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003e-24 h\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0 h\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003e+\u0026thinsp;24 h\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eRight Cornea\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e34.90 (34.10\u0026ndash;36.20)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e34.80 (33.50\u0026ndash;37.00)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e34.70 (33.10\u0026ndash;36.50)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e35.00 (33.50\u0026ndash;35.80)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e34.90 (34.00-35.70)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e34.80 (34.00-36.20)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e0.852\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLeft Cornea\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e35.00 (33.90\u0026ndash;36.30)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e34.70 (33.60\u0026ndash;36.50)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e34.60 (33.40\u0026ndash;36.00)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e35.00 (34.00-36.50)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e34.80 (33.30\u0026ndash;35.60)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e35.00 (33.50\u0026ndash;37.30)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e0.328\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMedial Canthus\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e36.00 (34.00\u0026ndash;37.00)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e36.00 (33.70\u0026ndash;37.50)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e35.10 (33.80\u0026ndash;37.30)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e36.00 (34.20\u0026ndash;37.40)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e36.00 (33.50\u0026ndash;36.90)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e36.00 (34.20\u0026ndash;36.50)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e0.294\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLacrimal Sac\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e35.90 (34.10\u0026ndash;37.30)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e36.00 (33.70\u0026ndash;37.50)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e35.70 (34.20\u0026ndash;36.30)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e36.00 (35.10\u0026ndash;36.90)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e35.20 (34.00-36.50)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e35.80 (33.70\u0026ndash;36.50)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e0.124\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLateral Udder\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e35.00 (33.00-37.30)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e35.00 (34.00-36.50)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e34.80 (32.00-36.20)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e35.90 (33.50\u0026ndash;36.60)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e35.80 (34.00-37.80)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e36.00 (33.60\u0026ndash;37.50)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e0.026*\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCaudal Udder\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e34.80 (34.10\u0026ndash;35.60)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e35.00 (32.50\u0026ndash;36.50)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e34.70 (33.90\u0026ndash;36.30)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e34.70 (33.80\u0026ndash;36.10)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e35.00 (33.90\u0026ndash;37.00)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e35.00 (34.00-36.30)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e0.392\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eVulva\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e34.50 (32.00-35.60)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e34.00 (31.20\u0026ndash;36.00)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e34.00 (31.00-35.60)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e33.90 (31.60\u0026ndash;35.60)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e32.80 (31.00-34.50)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e34.00 (32.50\u0026ndash;35.00)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e0.092\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe main finding of the present study was that, despite a marked decline in serum progesterone concentrations during the final 96 hours before parturition, thermal responses varied by anatomical site and were not consistently aligned with hormonal changes. A significant increase in the lateral udder surface temperature was the most notable thermographic observation, whereas vulvar and ocular temperatures did not demonstrate significant temporal variation. These results partially support the initial hypothesis that surface temperatures in the ocular, udder, and vulvar regions would decrease in line with progesterone decline and serve as reliable, non-invasive indicators of impending parturition.\u003c/p\u003e\u003cp\u003eThe gradual elevation in lateral udder temperature may be explained by increased mammary perfusion and metabolic activity associated with the onset of colostrum synthesis, rather than being a direct reflection of systemic hormonal withdrawal. Previous work in ewes demonstrated a progressive decline in body surface temperature measured at the upper neck prior to lambing, which was interpreted as a result of reduced metabolic heat production following luteolysis and progesterone decline (Nabenishi and Yamazaki \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). General body surface sites tend to reflect systemic thermoregulatory changes, whereas the mammary gland is influenced by localized functional activity related to the onset of lactation. These region-specific dynamics may explain the distinct temperature increases observed in the udder during the prepartum period (Teja et al. \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2023\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eThe positive correlation between vulvar surface temperature and progesterone, although statistically significant, was weak and not in line with physiological expectations. Some studies have reported a drop in perineal temperature before parturition, often linked to hormonal effects on blood flow (Mincu et al. \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; de Ruediger et al. \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). Another study has described a pattern where vulvar temperature first decreases, then rises again shortly before calving (Teja et al. \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). The slight temperature decrease observed in this study may be related to the hormonal activity. The lack of temperature change in the ocular and periorbital regions is consistent with earlier studies showing that these areas are not particularly responsive to reproductive hormonal fluctuations (Suthar et al. 2011; Martello et al. 2016). Strong autonomic regulation in these areas likely minimises thermal fluctuations, when focused on sites with greater hormonal or metabolic responsiveness.\u003c/p\u003e\u003cp\u003eThe absence of differences between animals giving birth during daytime and nighttime further supports the robustness of the thermal data, as some previous observations had identified circadian effects in body temperature rhythms prior to parturition (Nabenishi and Yamazaki \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). However, a report also exists showing that circadian patterns become less distinct as parturition approaches, possibly due to overriding hormonal or behavioral drivers (Teja et al. \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). The current findings align more closely with those studies and suggest that time of day does not significantly influence surface temperature changes in the final phase of gestation.\u003c/p\u003e\u003cp\u003eThis study had several limitations. First, the relatively small sample size may have limited the statistical power to detect subtle thermal changes, particularly in regions with high individual variability. Second, although environmental conditions were monitored, minor fluctuations in ambient temperature or humidity could still have influenced surface temperature measurements. Third, thermal imaging was performed at fixed time intervals, which may have missed transient changes occurring between observations. Finally, progesterone was the only hormonal parameter assessed; evaluating additional reproductive hormones could provide a more complete understanding of prepartum thermal dynamics.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eSerum progesterone levels declined consistently in the days preceding parturition, yet thermal responses differed across regions, with the lateral udder showing the clearest change. Combining thermographic data with hormonal measurements appears to offer greater reliability for predicting parturition than using thermography alone, with the lateral udder and vulvar regions showing the highest potential value when integrated with endocrine information. However, the moderate strength of these associations underlines the need for further research to refine and validate thermographic approaches for broader application.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe would like to thank Burdur MAKÜ Agriculture, Livestock and Food Research Application and Research Center for allowing us to conduct this study on the animals in its farm.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eCortu A prepared the original draft of the manuscript, designed the study methodology, administered the project, and performed the investigation, formal analysis, and data curation. He also contributed to the conceptualization and visualization of the study and revised and edited the manuscript text. Kahraman D contributed to data curation, investigation, and visualization, and participated in revising and editing the manuscript text. All authors reviewed and edited all versions of the manuscript. All authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThis research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData Availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe data supporting the findings of this study are available in the: https://figshare.com/s/6eb10b9323fefb196110\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStatement of Animal Ethics\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was approved by the Burdur Mehmet Akif Ersoy University Animal Experiments Local Ethics Committee (Approval No: 2025/1502). All procedures involving animals were conducted in compliance with national regulations governing the ethical treatment and use of experimental animals.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of Interest Statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNone of the authors has any other financial or personal relationships that could inappropriately influence or bias the content of the paper.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eAoki M, Kimura K, Suzuki O (2005). Predicting time of parturition from changing vaginal temperature measured by data-logging apparatus in beef cows with twin fetuses. Anim Reprod Sci 86(1-2):1\u0026ndash;12. https://doi.org/10.1016/j.anireprosci.2004.04.046\u003c/li\u003e\n\u003cli\u003eBerry RJ, Kennedy AD, Scott SL, Kyle BL, Schaefer AL (2003). Daily variation in the udder surface temperature of dairy cows measured by infrared thermography: Potential for mastitis detection. Can J Anim Sci 83(4):687\u0026ndash;693. https://doi.org/10.4141/A03-01.\u003c/li\u003e\n\u003cli\u003eBurfeind O, Suthar VS, Voigtsberger R, Bonk S, Heuwieser W (2014). Body temperature in early postpartum dairy cows. Theriogenology 82(1):121\u0026ndash;131. https://10.1016/j.theriogenology.2014.03.006.\u003c/li\u003e\n\u003cli\u003eBurfeind O, Suthar VS, Voigtsberger R, Bonk S, Heuwieser W (2011). Validity of prepartum changes in vaginal and rectal temperature to predict calving in dairy cows. J Dairy Sci 94(10):5053\u0026ndash;5061. https://doi.org/10.3168/jds.2011-4484.\u003c/li\u003e\n\u003cli\u003eColak A, Polat B, Okumus Z, Kaya M, Yanmaz LE, Hayirli A (2008). Early detection of mastitis using infrared thermography in dairy cows. J Dairy Sci 91(11):4244\u0026ndash;8. https://doi.org/10.3168/jds.2008-1258.\u003c/li\u003e\n\u003cli\u003ede Ruediger FR, Yamada PH, Bicas Barbosa LG, Mungai Chacur MG, Pinheiro Ferreira JC, de Carvalho NAT, Milani Soriano GA, Codognoto VM, Oba E (2018). Effect of estrous cycle phase on vulvar, orbital area and muzzle surface temperatures as determined using digital infrared thermography in buffalo. Anim Reprod Sci 197:154\u0026ndash;161. https://10.1016/j.anireprosci.2018.08.023.\u003c/li\u003e\n\u003cli\u003eKorelidou V, Grbovic Z, Pavlovic D, Simovic I, Panic M, Temenos A, Gelasakis AI (2025). Clinical assessment of dairy goats\u0026rsquo; udder health using infrared thermography. Animals (Basel) 15(5):658. https://doi.org/10.3390/ani15050658.\u003c/li\u003e\n\u003cli\u003eKoyama K, Koyama T, Sugimoto M, Kusakari N, Miura R, Yoshioka K, Hirako M (2018). Prediction of calving time in Holstein dairy cows by monitoring the ventral tail base surface temperature. Vet J 240:1\u0026ndash;5. https://doi.org/10.1016/j.tvjl.2018.08.006.\u003c/li\u003e\n\u003cli\u003eMee JF (2008). Prevalence and risk factors for dystocia in dairy cattle: A review. Vet J 176(1):93\u0026ndash;101. https://doi.org/10.1016/j.tvjl.2007.12.032.\u003c/li\u003e\n\u003cli\u003eMincu M, Nicolae I, Gavojdian D (2023). Infrared thermography as a non-invasive method for evaluating stress in lactating dairy cows during isolation challenges. Front Vet Sci 10:1236668. https://10.3389/fvets.2023.1236668.\u003c/li\u003e\n\u003cli\u003eNabenishi H, Yamazaki A (2017). Decrease in body surface temperature before parturition in ewes. J Reprod Dev 63(2):185\u0026ndash;190. https://doi.org/10.1262/jrd.2016-097.\u003c/li\u003e\n\u003cli\u003eOuellet V, Vasseur E, Heuwieser W, Burfeind O, Maldague X, Charbonneau \u0026Eacute; (2016). Evaluation of calving indicators measured by automated monitoring devices to predict the onset of calving in Holstein dairy cows. J Dairy Sci 99(2):1539\u0026ndash;1548. https://doi.org/10.3168/jds.2015-10057.\u003c/li\u003e\n\u003cli\u003ePolat B, Colak A, Cengiz M, Yanmaz LE, Oral H, Bastan A, Kaya S, Hayirli A (2010). Sensitivity and specificity of infrared thermography in detection of subclinical mastitis in dairy cows. J Dairy Sci 93(8):3525\u0026ndash;3532. https://doi.org/10.3168/jds.2009-2807.\u003c/li\u003e\n\u003cli\u003eSchaefer AL, Perez Marquez HJ, Bench CJ (2025). The use of infrared thermography in the assessment of stress, health, and metabolism in domestic animals. Can J Anim Sci 105:1\u0026ndash;13. https://doi.org/10.1139/cjas-2024-0067.\u003c/li\u003e\n\u003cli\u003eTeja A, Sakthivel J, Ananda Rao K, Kumaresan A, Ramesha KP, Krishnaswamy N, Gowtham Varma C, Sivaram M, Lavanya M, Gowdar Veerappa V, Kataktalware MA, Das DN, Majumder K, Rajbangshi N (2023). Digital infrared thermal imaging of udder skin surface temperature: a novel non-invasive technology to monitor calving process in Murrah buffalo (Bubalus bubalis). Sci Rep 13(1):13207. https://10.1038/s41598-023- 40447-4.\u003c/li\u003e\n\u003cli\u003eTeja A, Sakthivel J, Rao KA, Krishnaswamy N, Chintalapati GV, Veerappa VG, Kumaresan A, Ramesha KP, Sivaram M, Kataktalware MA, Das DN, Mula RK, Lavanya M (2025). Thermal signatures of vulval skin surface: a potential non-invasive diagnostic technology to monitor the calving process in water buffalo (Bubalus bubalis). Reprod Domest Anim 60(5):e70065. https://doi.org/10.1111/rda.70065.\u003c/li\u003e\n\u003cli\u003eTeja A, Sakthivel J, Rao KA, Krishnaswamy N, Chintalapati GV, Veerappa VG, Kumaresan A, Ramesha KP, Sivaram M, Kataktalware MA, Das DN, Mula RK, Lavanya M (2025). Thermal signatures of vulval skin surface: a potential non-invasive diagnostic technology to monitor the calving process in water buffalo (Bubalus bubalis). Reprod Domest Anim 60(5):e70065. https://10.1111/rda.70065.\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":"Eye, goat, parturition, progesterone, thermography, udder","lastPublishedDoi":"10.21203/rs.3.rs-7583725/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7583725/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThis study aimed to investigate changes in surface temperatures of the eye, udder, and vulvar region in goats, alongside serum progesterone levels, to determine whether these parameters may collectively indicate impending parturition. Fifteen clinically healthy Honamli goats were synchronized for estrus and artificially inseminated. Serum samples were collected every 24 hours from 96 hours before to 24 hours after parturition for progesterone analysis. Infrared thermographic images were obtained every 6 hours from 11 anatomical sites: right and left cornea, right and left medial canthus, right and left lacrimal sac, right and left lateral udder, right and left caudal udder, and the vulvar region. Among these, only the lateral udder and vulvar temperatures were significantly associated with progesterone concentrations. Serum progesterone declined significantly as parturition approached (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), with values at 96 and 72 hours before parturition significantly higher than those at parturition and 24 hours postpartum. Lateral udder temperature showed a weak negative correlation with progesterone levels (\u003cem\u003er\u003c/em\u003e\u003csub\u003e\u003cem\u003es\u003c/em\u003e\u003c/sub\u003e = -0.274, p\u0026thinsp;=\u0026thinsp;0.009), whereas vulvar temperature showed a weak positive correlation (\u003cem\u003er\u003c/em\u003e\u003csub\u003e\u003cem\u003es\u003c/em\u003e\u003c/sub\u003e = 0.311, p\u0026thinsp;=\u0026thinsp;0.003). A significant temporal increase was observed only in lateral udder temperature (p\u0026thinsp;=\u0026thinsp;0.026). No significant differences were found between animals delivering during the daytime and those delivering at night. In conclusion, combining surface temperature measurements from specific anatomical regions with serum progesterone levels may improve the accuracy of parturition prediction in goats. However, the relatively weak associations and regional variability indicate the need for further research before clinical implementation.\u003c/p\u003e","manuscriptTitle":"Evaluation of Eye, Udder, and Vulvar Surface Temperatures Combined with Serum Progesterone for Detecting Parturition Time in Goats","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-09-23 07:05:06","doi":"10.21203/rs.3.rs-7583725/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":"3faf2176-1fbf-441e-932f-ff5f30108391","owner":[],"postedDate":"September 23rd, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-09-27T08:23:53+00:00","versionOfRecord":[],"versionCreatedAt":"2025-09-23 07:05:06","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7583725","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7583725","identity":"rs-7583725","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}