Ultrasound-guided minimally invasive thoracotomy for removal of migrating grass awn in a cat

Ultrasound-guided minimally invasive thoracotomy for removal of migrating grass awn in a cat | 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 Case Report Ultrasound-guided minimally invasive thoracotomy for removal of migrating grass awn in a cat Vicente Francisco Ratto Valderrama, Federica Valeri, Domenico Caivano, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7762463/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 20 Jan, 2026 Read the published version in Veterinary Research Communications → Version 1 posted 11 You are reading this latest preprint version Abstract Migrating grass awns are a rare cause of thoracic reactions in cats, resulting in pleural effusion, inflammation, and granulomatous responses. Diagnosis and localization are challenging, and treatment commonly requires invasive surgical intervention. We report a case of a 5-year-old, neutered male, domestic shorthair cat referred for pleural effusion and suspected intrathoracic vegetal foreign body. Thoracic ultrasonography confirmed the presence of pleural effusion and a linear hyperechoic structure within the pleural space was visualized. An ultrasound-guided minimally invasive thoracotomy was performed through the right fifth intercostal space and intraoperative ultrasonography was useful to precisely locate and remove the foreign body using a Hartmann ear forceps. Cytological analysis was performed on the pleural fluid and bacteriological analysis was performed on both the pleural fluid and the retrieved foreign body. The cytologic findings were consistent with an exudative effusion but no bacteria were isolated on both direct and enrichment bacterial cultures; empirical antibiotic treatment with marbofloxacin was continued. The patient recovered uneventfully, and follow-up revealed complete resolution of the clinical signs. This case report highlights the effectiveness of ultrasound-guided minimally invasive approach for intrathoracic vegetal foreign body removal in a cat. The transthoracic and intraoperative ultrasound can be useful for visualization and exact localization of the grass awn, minimizing surgical trauma and improving the outcome. Foreign body foxtail surgery ultrasonography feline Figures Figure 1 Figure 2 Figure 3 Background Barbed vegetal foreign bodies can enter the body through inhalation or transcutaneous penetration, especially in outdoor animals; whereas this is well recognized in hunting or working dogs, it remains less frequently reported in cats (Schultz et al. 2008; Cola et al. 2019 ; Caivano et al. 2023). Once inside, these awns are able to migrate through tissues in a unidirectional manner due to their barbed morphology, making unlikely their spontaneous expulsion or retrograde movement. This leads to progressive tissue disruption and can result in chronic inflammation, granuloma formation, abscessation, or septic pleuritis. In some cases, clinical signs can be subtle or transient, especially if partially masked by empirical treatment with antibiotic and/or anti-inflammatory drugs. This can delay diagnosis and allow the migration of the grass awn through the body. It is hypothesized that inhaled grass awns can reach the lower airways via the trachea and caudal bronchi, eventually perforating lung tissue and migrating into adjacent structures such as the pleural or pericardial space or even the abdominal and retroperitoneal cavities (Frendin et al. 1994 ; Frendin et al. 1999 ; Caivano et al. 2014 ; Caivano et al. 2016 ; Birettoni et al. 2017 ; Caivano et al. 2019 ; Hopper et al. 2004 ; Marchesi et al. 2020 ). Diagnosis is often challenging and standard imaging modalities such as ultrasonography, CT, or MRI can aid in the initial diagnosis (Schultz et al. 2008; Swinbourne et al, 2011; Whitty et al., 2013; Caivano et al. 2023). Ultrasonography has been previously reported to detect, localize, and guide removal of vegetal foreign bodies in dogs and cats (Caivano et al. 2016 ; Cola et al. 2019 ). However, ultrasonography can fail to detect the vegetal foreign body especially if the migration occurs in pleural space: the presence of scattered hyperechoic elements (fibrin, tissue remnants, cellular debris, or air) can limit the visualization of the awn (Caivano et al. 2016 ). Definitive treatment requires surgical removal of the foreign body. Traditional thoracotomy is effective, but it can be associated with significant complications (tissue trauma, postoperative pain, and long recovery time) (Stillion et al. 2015). Minimally invasive techniques, such as thoracoscopy or targeted thoracotomy under imaging guidance, offer a less traumatic alternative. In the present case, we describe the successful removal of migrating intrathoracic grass awn in a cat using an ultrasound-guided minimally invasive surgical approach. The report highlights the usefulness of the transthoracic and intraoperative ultrasonography to visualize and exact locate the grass awn, minimizing surgical trauma and improving the outcome. Case Presentation A five-year-old, neutered male domestic shorthair, was referred to the Veterinary Teaching Hospital of Perugia University for pleural effusion and suspected intrathoracic vegetal foreign body. Thoracic radiographs performed by the referring veterinarian showed a moderate pleural effusion with loss of cardiac and diaphragmatic silhouette definition. The referring veterinarian had visualized a hyperechoic structure during the ultrasonographic examination of the thorax. The cat was treated with marbofloxacin (2 mg/kg, PO, q 24 h) for two days prior to the presentation. On the physical examination, the cat revealed dyspnea and hyperthermia (39.5°C). Thoracic ultrasonography subsequently confirmed the presence of pleural effusion, appearing moderately echogenic and heterogenous, consistent with a purulent exudate. A hyperechoic, linear structure located within the right caudal mediastinum was also visualized. This structure was characterized by two hyperechogenic bands casting an acoustic shadow, consistent with a migrating vegetal foreign body (Fig. 1 ). Based on these findings, surgical removal of the migrating grass awn was planned. Preoperative ultrasonographic examination repeated under general anesthesia on the day of the surgery, revealed cranial migration of the vegetal foreign body. It was now visualized within the cranial mediastinum near the heart. Aseptic preparation and trichotomy were performed over the right hemithorax. A small skin incision (1 x 1 cm) was made at the level of the 5th intercostal space. The underlying pectoral muscle was gently retracted to expose the intercostal musculature. A minor incision (0.5 x 0.5 cm) through the external and internal intercostal muscles was made, allowing insertion of a blunt probe (speculum guide). Under continuous ultrasonographic guidance, the probe was positioned tangential to the heart in direct contact with the tip of the grass awn, allowing optimal alignment for the surgical approach. Once the foreign body was precisely localized, the guide probe was withdrawn and replaced with a Hartmann ear forceps. The forceps was advanced through the thoracic incision, and the vegetal foreign body was carefully grasped and extracted in a single maneuver under real-time ultrasound guidance (Fig. 2 , Fig. 3 and Supplementary file 1). Prior to closure, approximately 40 mL of moderately turbid, purulent fluid was aspirated from the pleural cavity. The pleural space was then thoroughly lavaged with warm sterile saline. Before standard fascial and skin closure, a 12 French (4 mm) chest drain was placed. The retrieved foreign body, morphologically consistent with a grass awn ( Hordeum spp.), and the aspirated pleural effusion were submitted for microbiological culture, both yielding negative results, including after enrichment culture. Cytological examination of the pleural fluid, assessed via four cytospin-prepared slides, revealed a highly cellular sample with mild hemolysis. The inflammatory profile was mixed, predominated by mature segmented neutrophils (approximately 50%), some of which exhibited degenerative changes including karyolysis, karyorrhexis, and pyknosis. Activated macrophages with vacuolated cytoplasm comprised roughly 30% of the total cellular population, whereas small to medium lymphocytes accounted for the remaining 20%. Occasional reactive mesothelial cells were also observed. No microorganisms were visualized. The cytologic findings were consistent with an exudative effusion displaying a nonspecific mixed neutrophilic and macrophagic inflammatory pattern. Despite the absence of identifiable bacteria, the presence of degenerate neutrophils supported the decision to maintain empirical antibiotic treatment (marbofloxacin). A thoracic bandage was maintained for three days postoperatively and the patient was discharged three days after surgery. Sutures were scheduled for removal ten to twelve days following the procedure. A follow-up thoracic ultrasound was planned at the conclusion of antibiotic therapy (after 10 days) to confirm resolution of the effusion and to rule out any residual or recurrent clinical signs. Discussion and Conclusions Migration of vegetal foreign bodies, such as Hordeum spp. grass awns, is relatively uncommon in cats and it can represent a significant diagnostic and therapeutic challenge due to their subtle clinical presentation and complexity of the detection and removal. Cola et al. described the use of ultrasonography in detecting thoracic grass awns in 4 cats presented for respiratory signs (Cola et al. 2019 ). Ultrasound examination showed unilateral pleural effusion and atelectasis of the ventral portion of the lung lobes of the affected side in all cats. In one cat, a mediastinal spindle-shaped structure characterized by two hyperechogenic walls separated by a central hypoechogenic band, compatible with a vegetal foreign body, was visualized during the first ultrasonographic scan. In the other 3 cats, 3 to 5 ultrasonographic examinations repeated on different days were required to identify the foreign bodies in the thoracic cavity. This lower incidence in cats compared to dogs can be explained by distinct feline behaviors, such as meticulous grooming, predominantly nasal breathing with the mouth closed, and a reduced tendency to ingest foreign material (Schultz et al. 2008; Koutinas et al. 2003 ; Leal et al. 2017 ). When vegetal foreign bodies migrate into the thoracic cavity, their visualization can be particularly challenging. Pulmonary consolidation associated with migrating grass awn can help as an indirect indicator, guiding the ultrasonographer toward the area of interest and facilitating localization of the migrating foreign body (Caivano et al. 2023). Ultrasonographic visualization of the vegetal foreign body within the pleural space is often limited by the presence of hyperechoic artifacts such as fibrin, tissue fragments, cellular debris, or small air bubbles. In our case, the vegetal foreign body was visualized within the pleural space and ultrasonography allowed to reveal its spontaneous movements within the effusion and migration, facilitating the localization and planning the surgical approach. The standard surgical approach for removing migrating grass awns in the thoracic cavity typically involves either thoracotomy or thoracoscopy in dogs and cats. Thoracotomy, whereas providing direct access and visibility, is associated with significant tissue trauma, postoperative pain, and longer hospitalization and recovery times. Thoracoscopy, despite being less invasive and associated with faster recovery, requires specialized equipment and advanced technical skills. However, both approaches can involve extended convalescence and are not without risk of complications (Stillion et al. 2015). Moreover, thoracoscopy can not always be a feasible option: chronic inflammation, often associated with long-standing foreign body presence, can lead to the formation of pleural adhesions. These adhesions impair visualization and limit the maneuverability of thoracoscopic instruments, reducing the feasibility of a minimally invasive approach. In such cases, conversion to open-chest surgery (thoracotomy) is often necessary to ensure safe and complete foreign body removal. Cola et al. reported surgical approach in 4 cats with migrating intrathoracic grass awns. In 2 cats the surgical approach consisted of a video-assisted thoracoscopy with the cat in dorsal recumbency. However, in 1 of these cats video-assisted thoracoscopy was attempted but conversion to intercostal thoracotomy was necessary because of numerous adhesions between the visceral and parietal pleura. In another 2 cats, intercostal thoracotomy was used to reach the mediastinum. In all cats, the vegetal foreign body was removed. In our case, the combination of real-time ultrasonographic guidance with a minimally invasive surgical technique allowed for successful removal of the grass awn. Moreover, the precise localization of the mobile foreign body allowed to minimize surgical trauma and increase procedural safety. Finally, the cat was discharged just three days postoperatively with minimal surgical morbidity and a rapid recovery. Cytological analysis of the pleural fluid revealed a purulent exudate with no visible microorganisms and negative results on both direct and enrichment bacterial cultures. This is not surprising, considering that the cat had received marbofloxacin prior to referral. This preexisting antimicrobial therapy can have suppressed bacterial growth or eliminated susceptible pathogens, potentially masking an underlying infection. In conclusion, this case highlights the diagnostic and therapeutic value of the ultrasonography for managing migrating intrathoracic vegetal foreign bodies in a feline patient and demonstrates that, in selected cases, a tailored minimally invasive approach can provide an effective alternative to more invasive traditional techniques. Ultrasonography, guiding entirely the mini-invasive procedure, facilitated precise localization and reduced surgical trauma, potentially leading to faster recovery compared to more invasive approaches. Although intrathoracic migration of vegetal foreign bodies is rarely reported in feline patients, it remains a critical differential diagnosis in cases of pleural effusion. Declarations Ethics approval: Ethical review and approval were waived for this study because, being a case report derived from clinical practice, all medical procedures were performed after obtaining written consent from the owner. Competing interests: The authors declare no competing interests. Funding: This research received no external funding. Author Contribution All authors contributed to the study conception and design. Investigation was performed by Dr. Antonello Bufalari, Dr. Giulia Moretti and Dr. Domenico Caivano. The first draft of the manuscript was written by Dr. Vicente Francisco Ratto Valderrama, Dr. Federica Valeri and Dr. Domenico Caivano. All authors commented on previous versions of the manuscript. All authors read and approved the final manuscript. Acknowledgement Authors gratefully thank Mr. Corrado Pallotta for the technical support. Data Availability The data presented in this study are available in the article. References Birettoni, F.; Caivano, D.; Rishniw, M.; Moretti, G.; Porciello, F.; Giorgi, M.E.; Crovace, A.; Bianchini, E.; Bufalari, A. Preoperative and intraoperative ultrasound aids removal of migrating plant material causing iliopsoas myositis via ventral midline laparotomy: A study of 22 dogs. Acta Vet. Scand. 2017, 59, 12. Caivano, D.; Bufalari, A.; Elena Giorgi, M.; Conti, M.B.; Marchesi, M.C.; Angeli, G.; Porciello, F.; Birettoni, F. Imaging diagnosis-transesophageal ultrasound-guided removal of a migrating grass awn foreign body in a dog. Vet. Radiol. Ultrasound 2014, 55, 561–564. Caivano, D.; Birettoni, F.; Rishniw, M.; Bufalari, A.; De Monte, V.; Proni, A.; Giorgi, M.E.; Porciello, F. Ultrasonographic findings and outcomes of dogs with suspected migrating intrathoracic grass awns: 43 cases (2010–2013). J. Am. Vet. Med. Assoc. 2016, 248, 413–421. Caivano, D.; Birettoni, F.; Marchesi, M.C.; Moretti, G.; Corda, A.; Petrescu, V.F.; Porciello, F.; Bufalari, A. Septic pericarditis and cardiac tamponade caused by migrating intrathoracic grass awn in an English setter dog. Isr. J. Vet. Med. 2019, 74, 82–87. Caivano, D.; Corda, F.;Corda, A.; Moretti, G.; Bufalari, A.; Application of Ultrasound in Detecting and Removing Migrating Grass Awns in Dogs and Cats: A Systematic Review. Animals 2023, 13, 2071. https://doi.org/10.3390/ani13132071 Cola, V.; Del Magno, S.; Valentini, S.; Zanardi, S.; Foglia, A.; Spinella, G.; Capitani, O.; Buracco, P.; Pisoni, L. Deep vegetal foreign bodies in cats: A retrospective study of 10 cases. J. Am. Anim. Hosp. Assoc. 2019, 55, 249–255. Marchesi, M.C.; Moretti, G.; Angeli, G.; Birettoni, F.; Porciello, F.; Bufalari, A.; Caivano, D. Prostatic localization of a migrating grass awn foreign body in a dog. Vet. Sci. 2020, 7, 192. Frendin, J.; Grekot, C.; Hellmen, E.; Iwarssons, M.; Gunnarsson, A.; Chryssantou, E. Thoracic and abdominal wall swellings in caused by foreign bodies. J. Small Anim. Pract. 1994, 35, 499–508. Frendin, J.; Hansson, K.; Lonnemark, M.; Carlsten, J. Diagnostic imaging of foreign body reactions in dogs with diffuse back pain. J. Small Anim. Pract. 1999, 40, 278–285. Hopper, B.J.; Lester, N.V.; Irwin, P.J.; Eger, C.E.; Richardson, J.L. Imaging diagnosis: Pneumothorax and focal peritonitis in a dog due to migration of an inhaled grass awn. Vet. Radiol. Ultrasound 2004, 45, 136–138. Koutinas CK, Papazoglou LG, Saridomichelakis MN, et al. Caudal mediastinal abscess due to a grass awn (Hordeum spp) in a cat. J Feline Med Surg 2003;5(1):43–6. Leal RO, Bongrand Y, Lepoutre JG, et al. Tracheobronchial foreign bodies in cats: a retrospective study of 12 cases. J Feline Med Surg 2017;19(2):117–22. Schultz, R.M.; Zwingenberger, A. Radiographic, computed tomographic, and ultrasonographic findings with migrating intrathoracic grass awns in dogs and cats. Vet. Radiol. Ultrasound 2008, 49, 249–255. Stillion JR, Letendre JA. A clinical review of the pathophysiology, diagnosis, and treatment of pyothorax in dogs and cats. J Vet Emerg Crit Care2015;25(1):113–29. Additional Declarations No competing interests reported. Supplementary Files Supplementaryfile1.mov Cite Share Download PDF Status: Published Journal Publication published 20 Jan, 2026 Read the published version in Veterinary Research Communications → Version 1 posted Editorial decision: Revision requested 17 Nov, 2025 Reviews received at journal 17 Nov, 2025 Reviews received at journal 10 Nov, 2025 Reviewers agreed at journal 02 Nov, 2025 Reviews received at journal 01 Nov, 2025 Reviewers agreed at journal 01 Nov, 2025 Reviewers agreed at journal 08 Oct, 2025 Reviewers invited by journal 03 Oct, 2025 Editor assigned by journal 03 Oct, 2025 Submission checks completed at journal 03 Oct, 2025 First submitted to journal 01 Oct, 2025 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. 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1","display":"","copyAsset":false,"role":"figure","size":82994,"visible":true,"origin":"","legend":"\u003cp\u003eLong axis (a) and short axis (b) transthoracic ultrasonographic image of the caudal mediastinum showing pleural effusion and a spindle-shaped hyperechoic foreign body consistent with a grass awn. The tip (arrowhead) and the barbs (arrow) of the awn are evident in long axis image (a). The vegetal foreign body (arrowhead) shows an acoustic shadowing in short axis (b). H, heart; Li, liver; Lu, lung; C, caudal vena cava.\u003c/p\u003e","description":"","filename":"1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7762463/v1/0318029aaaba72eccb66c9a3.jpg"},{"id":93728107,"identity":"9ab27f29-5d51-4ef3-903f-78b03ebb7779","added_by":"auto","created_at":"2025-10-17 02:10:31","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":97533,"visible":true,"origin":"","legend":"\u003cp\u003eIntraoperative ultrasonographic image of the grass awn (arrowhead) migrated within the cranial mediastinum (a) and the Hartmann ear forceps (arrowhead) advanced through the thoracic incision within the pleural space (b).\u003c/p\u003e","description":"","filename":"2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7762463/v1/1f4bfce147bb45478323b971.jpg"},{"id":93728099,"identity":"1d991c1d-da24-401a-9a9e-7985e7f72552","added_by":"auto","created_at":"2025-10-17 02:10:30","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":87771,"visible":true,"origin":"","legend":"\u003cp\u003eIntraoperative photograph illustrating the surgical field and successful extraction of the vegetal foreign body. The image shows the small thoracotomy site (approximately 0.5 cm x 0.5 cm) over the right cranial hemithorax, the Hartmann ear forceps holding the retrieved grass awn, a #15 scalpel blade placed alongside for scale reference and the ultrasound probe used for echo-guided procedure.\u003c/p\u003e","description":"","filename":"3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7762463/v1/26068524324b57431ba29c38.jpg"},{"id":101152049,"identity":"eb28c2ec-e599-46df-b468-2970445931d4","added_by":"auto","created_at":"2026-01-26 16:09:21","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":617426,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7762463/v1/6be7c5c3-3ec4-4228-a0a8-aa9f7153ab70.pdf"},{"id":93728175,"identity":"3119545b-791c-406b-999f-e0ec2cbb2d8c","added_by":"auto","created_at":"2025-10-17 02:10:37","extension":"mov","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":1636075,"visible":true,"origin":"","legend":"","description":"","filename":"Supplementaryfile1.mov","url":"https://assets-eu.researchsquare.com/files/rs-7762463/v1/70b5b86483c1b02341b96260.mov"}],"financialInterests":"No competing interests reported.","formattedTitle":"Ultrasound-guided minimally invasive thoracotomy for removal of migrating grass awn in a cat","fulltext":[{"header":"Background","content":"\u003cp\u003eBarbed vegetal foreign bodies can enter the body through inhalation or transcutaneous penetration, especially in outdoor animals; whereas this is well recognized in hunting or working dogs, it remains less frequently reported in cats (Schultz et al. 2008; Cola et al. \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Caivano et al. 2023). Once inside, these awns are able to migrate through tissues in a unidirectional manner due to their barbed morphology, making unlikely their spontaneous expulsion or retrograde movement. This leads to progressive tissue disruption and can result in chronic inflammation, granuloma formation, abscessation, or septic pleuritis. In some cases, clinical signs can be subtle or transient, especially if partially masked by empirical treatment with antibiotic and/or anti-inflammatory drugs. This can delay diagnosis and allow the migration of the grass awn through the body. It is hypothesized that inhaled grass awns can reach the lower airways via the trachea and caudal bronchi, eventually perforating lung tissue and migrating into adjacent structures such as the pleural or pericardial space or even the abdominal and retroperitoneal cavities (Frendin et al. \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e1994\u003c/span\u003e; Frendin et al. \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e1999\u003c/span\u003e; Caivano et al. \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; Caivano et al. \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Birettoni et al. \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Caivano et al. \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2019\u003c/span\u003e; Hopper et al. \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2004\u003c/span\u003e; Marchesi et al. \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2020\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eDiagnosis is often challenging and standard imaging modalities such as ultrasonography, CT, or MRI can aid in the initial diagnosis (Schultz et al. 2008; Swinbourne et al, 2011; Whitty et al., 2013; Caivano et al. 2023). Ultrasonography has been previously reported to detect, localize, and guide removal of vegetal foreign bodies in dogs and cats (Caivano et al. \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Cola et al. \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). However, ultrasonography can fail to detect the vegetal foreign body especially if the migration occurs in pleural space: the presence of scattered hyperechoic elements (fibrin, tissue remnants, cellular debris, or air) can limit the visualization of the awn (Caivano et al. \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2016\u003c/span\u003e). Definitive treatment requires surgical removal of the foreign body. Traditional thoracotomy is effective, but it can be associated with significant complications (tissue trauma, postoperative pain, and long recovery time) (Stillion et al. 2015). Minimally invasive techniques, such as thoracoscopy or targeted thoracotomy under imaging guidance, offer a less traumatic alternative.\u003c/p\u003e\u003cp\u003eIn the present case, we describe the successful removal of migrating intrathoracic grass awn in a cat using an ultrasound-guided minimally invasive surgical approach. The report highlights the usefulness of the transthoracic and intraoperative ultrasonography to visualize and exact locate the grass awn, minimizing surgical trauma and improving the outcome.\u003c/p\u003e"},{"header":"Case Presentation","content":"\u003cp\u003eA five-year-old, neutered male domestic shorthair, was referred to the Veterinary Teaching Hospital of Perugia University for pleural effusion and suspected intrathoracic vegetal foreign body. Thoracic radiographs performed by the referring veterinarian showed a moderate pleural effusion with loss of cardiac and diaphragmatic silhouette definition. The referring veterinarian had visualized a hyperechoic structure during the ultrasonographic examination of the thorax. The cat was treated with marbofloxacin (2 mg/kg, PO, q 24 h) for two days prior to the presentation.\u003c/p\u003e\u003cp\u003eOn the physical examination, the cat revealed dyspnea and hyperthermia (39.5°C). Thoracic ultrasonography subsequently confirmed the presence of pleural effusion, appearing moderately echogenic and heterogenous, consistent with a purulent exudate. A hyperechoic, linear structure located within the right caudal mediastinum was also visualized. This structure was characterized by two hyperechogenic bands casting an acoustic shadow, consistent with a migrating vegetal foreign body (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eBased on these findings, surgical removal of the migrating grass awn was planned. Preoperative ultrasonographic examination repeated under general anesthesia on the day of the surgery, revealed cranial migration of the vegetal foreign body. It was now visualized within the cranial mediastinum near the heart.\u003c/p\u003e\u003cp\u003eAseptic preparation and trichotomy were performed over the right hemithorax. A small skin incision (1 x 1 cm) was made at the level of the 5th intercostal space. The underlying pectoral muscle was gently retracted to expose the intercostal musculature. A minor incision (0.5 x 0.5 cm) through the external and internal intercostal muscles was made, allowing insertion of a blunt probe (speculum guide). Under continuous ultrasonographic guidance, the probe was positioned tangential to the heart in direct contact with the tip of the grass awn, allowing optimal alignment for the surgical approach. Once the foreign body was precisely localized, the guide probe was withdrawn and replaced with a Hartmann ear forceps. The forceps was advanced through the thoracic incision, and the vegetal foreign body was carefully grasped and extracted in a single maneuver under real-time ultrasound guidance (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e and Supplementary file 1).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003ePrior to closure, approximately 40 mL of moderately turbid, purulent fluid was aspirated from the pleural cavity. The pleural space was then thoroughly lavaged with warm sterile saline. Before standard fascial and skin closure, a 12 French (4 mm) chest drain was placed. The retrieved foreign body, morphologically consistent with a grass awn (\u003cem\u003eHordeum\u003c/em\u003e spp.), and the aspirated pleural effusion were submitted for microbiological culture, both yielding negative results, including after enrichment culture. Cytological examination of the pleural fluid, assessed via four cytospin-prepared slides, revealed a highly cellular sample with mild hemolysis. The inflammatory profile was mixed, predominated by mature segmented neutrophils (approximately 50%), some of which exhibited degenerative changes including karyolysis, karyorrhexis, and pyknosis. Activated macrophages with vacuolated cytoplasm comprised roughly 30% of the total cellular population, whereas small to medium lymphocytes accounted for the remaining 20%. Occasional reactive mesothelial cells were also observed. No microorganisms were visualized. The cytologic findings were consistent with an exudative effusion displaying a nonspecific mixed neutrophilic and macrophagic inflammatory pattern. Despite the absence of identifiable bacteria, the presence of degenerate neutrophils supported the decision to maintain empirical antibiotic treatment (marbofloxacin).\u003c/p\u003e\u003cp\u003eA thoracic bandage was maintained for three days postoperatively and the patient was discharged three days after surgery. Sutures were scheduled for removal ten to twelve days following the procedure. A follow-up thoracic ultrasound was planned at the conclusion of antibiotic therapy (after 10 days) to confirm resolution of the effusion and to rule out any residual or recurrent clinical signs.\u003c/p\u003e"},{"header":"Discussion and Conclusions","content":"\u003cp\u003eMigration of vegetal foreign bodies, such as \u003cem\u003eHordeum\u003c/em\u003e spp. grass awns, is relatively uncommon in cats and it can represent a significant diagnostic and therapeutic challenge due to their subtle clinical presentation and complexity of the detection and removal. Cola et al. described the use of ultrasonography in detecting thoracic grass awns in 4 cats presented for respiratory signs (Cola et al. \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). Ultrasound examination showed unilateral pleural effusion and atelectasis of the ventral portion of the lung lobes of the affected side in all cats. In one cat, a mediastinal spindle-shaped structure characterized by two hyperechogenic walls separated by a central hypoechogenic band, compatible with a vegetal foreign body, was visualized during the first ultrasonographic scan. In the other 3 cats, 3 to 5 ultrasonographic examinations repeated on different days were required to identify the foreign bodies in the thoracic cavity. This lower incidence in cats compared to dogs can be explained by distinct feline behaviors, such as meticulous grooming, predominantly nasal breathing with the mouth closed, and a reduced tendency to ingest foreign material (Schultz et al. 2008; Koutinas et al. \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2003\u003c/span\u003e; Leal et al. \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). When vegetal foreign bodies migrate into the thoracic cavity, their visualization can be particularly challenging. Pulmonary consolidation associated with migrating grass awn can help as an indirect indicator, guiding the ultrasonographer toward the area of interest and facilitating localization of the migrating foreign body (Caivano et al. 2023). Ultrasonographic visualization of the vegetal foreign body within the pleural space is often limited by the presence of hyperechoic artifacts such as fibrin, tissue fragments, cellular debris, or small air bubbles. In our case, the vegetal foreign body was visualized within the pleural space and ultrasonography allowed to reveal its spontaneous movements within the effusion and migration, facilitating the localization and planning the surgical approach.\u003c/p\u003e\u003cp\u003eThe standard surgical approach for removing migrating grass awns in the thoracic cavity typically involves either thoracotomy or thoracoscopy in dogs and cats. Thoracotomy, whereas providing direct access and visibility, is associated with significant tissue trauma, postoperative pain, and longer hospitalization and recovery times. Thoracoscopy, despite being less invasive and associated with faster recovery, requires specialized equipment and advanced technical skills. However, both approaches can involve extended convalescence and are not without risk of complications (Stillion et al. 2015). Moreover, thoracoscopy can not always be a feasible option: chronic inflammation, often associated with long-standing foreign body presence, can lead to the formation of pleural adhesions. These adhesions impair visualization and limit the maneuverability of thoracoscopic instruments, reducing the feasibility of a minimally invasive approach. In such cases, conversion to open-chest surgery (thoracotomy) is often necessary to ensure safe and complete foreign body removal. Cola et al. reported surgical approach in 4 cats with migrating intrathoracic grass awns. In 2 cats the surgical approach consisted of a video-assisted thoracoscopy with the cat in dorsal recumbency. However, in 1 of these cats video-assisted thoracoscopy was attempted but conversion to intercostal thoracotomy was necessary because of numerous adhesions between the visceral and parietal pleura. In another 2 cats, intercostal thoracotomy was used to reach the mediastinum. In all cats, the vegetal foreign body was removed. In our case, the combination of real-time ultrasonographic guidance with a minimally invasive surgical technique allowed for successful removal of the grass awn. Moreover, the precise localization of the mobile foreign body allowed to minimize surgical trauma and increase procedural safety. Finally, the cat was discharged just three days postoperatively with minimal surgical morbidity and a rapid recovery.\u003c/p\u003e\u003cp\u003eCytological analysis of the pleural fluid revealed a purulent exudate with no visible microorganisms and negative results on both direct and enrichment bacterial cultures. This is not surprising, considering that the cat had received marbofloxacin prior to referral. This preexisting antimicrobial therapy can have suppressed bacterial growth or eliminated susceptible pathogens, potentially masking an underlying infection.\u003c/p\u003e\u003cp\u003eIn conclusion, this case highlights the diagnostic and therapeutic value of the ultrasonography for managing migrating intrathoracic vegetal foreign bodies in a feline patient and demonstrates that, in selected cases, a tailored minimally invasive approach can provide an effective alternative to more invasive traditional techniques. Ultrasonography, guiding entirely the mini-invasive procedure, facilitated precise localization and reduced surgical trauma, potentially leading to faster recovery compared to more invasive approaches. Although intrathoracic migration of vegetal foreign bodies is rarely reported in feline patients, it remains a critical differential diagnosis in cases of pleural effusion.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003ch2\u003eEthics approval:\u003c/h2\u003e\u003cp\u003eEthical review and approval were waived for this study because, being a case report derived from clinical practice, all medical procedures were performed after obtaining written consent from the owner.\u003c/p\u003e\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eCompeting interests:\u003c/strong\u003e\u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e\u003c/p\u003e\u003ch2\u003eFunding:\u003c/h2\u003e\u003cp\u003eThis research received no external funding.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eAll authors contributed to the study conception and design. Investigation was performed by Dr. Antonello Bufalari, Dr. Giulia Moretti and Dr. Domenico Caivano. The first draft of the manuscript was written by Dr. Vicente Francisco Ratto Valderrama, Dr. Federica Valeri and Dr. Domenico Caivano. All authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003eAuthors gratefully thank Mr. Corrado Pallotta for the technical support.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eThe data presented in this study are available in the article.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eBirettoni, F.; Caivano, D.; Rishniw, M.; Moretti, G.; Porciello, F.; Giorgi, M.E.; Crovace, A.; Bianchini, E.; Bufalari, A. Preoperative and intraoperative ultrasound aids removal of migrating plant material causing iliopsoas myositis via ventral midline laparotomy: A study of 22 dogs. Acta Vet. Scand. 2017, 59, 12.\u003c/li\u003e\n\u003cli\u003eCaivano, D.; Bufalari, A.; Elena Giorgi, M.; Conti, M.B.; Marchesi, M.C.; Angeli, G.; Porciello, F.; Birettoni, F. Imaging diagnosis-transesophageal ultrasound-guided removal of a migrating grass awn foreign body in a dog. Vet. Radiol. Ultrasound 2014, 55, 561\u0026ndash;564.\u003c/li\u003e\n\u003cli\u003eCaivano, D.; Birettoni, F.; Rishniw, M.; Bufalari, A.; De Monte, V.; Proni, A.; Giorgi, M.E.; Porciello, F. Ultrasonographic findings and outcomes of dogs with suspected migrating intrathoracic grass awns: 43 cases (2010\u0026ndash;2013). J. Am. Vet. Med. Assoc. 2016, 248, 413\u0026ndash;421.\u003c/li\u003e\n\u003cli\u003eCaivano, D.; Birettoni, F.; Marchesi, M.C.; Moretti, G.; Corda, A.; Petrescu, V.F.; Porciello, F.; Bufalari, A. Septic pericarditis and cardiac tamponade caused by migrating intrathoracic grass awn in an English setter dog. Isr. J. Vet. Med. 2019, 74, 82\u0026ndash;87.\u003c/li\u003e\n\u003cli\u003eCaivano, D.; Corda, F.;Corda, A.; Moretti, G.; Bufalari, A.; Application of Ultrasound in Detecting and Removing Migrating Grass Awns in Dogs and Cats: A Systematic Review. Animals 2023, 13, 2071. https://doi.org/10.3390/ani13132071\u003c/li\u003e\n\u003cli\u003eCola, V.; Del Magno, S.; Valentini, S.; Zanardi, S.; Foglia, A.; Spinella, G.; Capitani, O.; Buracco, P.; Pisoni, L. Deep vegetal foreign bodies in cats: A retrospective study of 10 cases. J. Am. Anim. Hosp. Assoc. 2019, 55, 249\u0026ndash;255.\u003c/li\u003e\n\u003cli\u003eMarchesi, M.C.; Moretti, G.; Angeli, G.; Birettoni, F.; Porciello, F.; Bufalari, A.; Caivano, D. Prostatic localization of a migrating grass awn foreign body in a dog. Vet. Sci. 2020, 7, 192.\u003c/li\u003e\n\u003cli\u003eFrendin, J.; Grekot, C.; Hellmen, E.; Iwarssons, M.; Gunnarsson, A.; Chryssantou, E. Thoracic and abdominal wall swellings in caused by foreign bodies. J. Small Anim. Pract. 1994, 35, 499\u0026ndash;508.\u003c/li\u003e\n\u003cli\u003eFrendin, J.; Hansson, K.; Lonnemark, M.; Carlsten, J. Diagnostic imaging of foreign body reactions in dogs with diffuse back pain. J. Small Anim. Pract. 1999, 40, 278\u0026ndash;285.\u003c/li\u003e\n\u003cli\u003eHopper, B.J.; Lester, N.V.; Irwin, P.J.; Eger, C.E.; Richardson, J.L. Imaging diagnosis: Pneumothorax and focal peritonitis in a dog due to migration of an inhaled grass awn. Vet. Radiol. Ultrasound 2004, 45, 136\u0026ndash;138.\u003c/li\u003e\n\u003cli\u003eKoutinas CK, Papazoglou LG, Saridomichelakis MN, et al. Caudal mediastinal abscess due to a grass awn (Hordeum spp) in a cat. J Feline Med Surg 2003;5(1):43\u0026ndash;6.\u003c/li\u003e\n\u003cli\u003eLeal RO, Bongrand Y, Lepoutre JG, et al. Tracheobronchial foreign bodies in cats: a retrospective study of 12 cases. J Feline Med Surg 2017;19(2):117\u0026ndash;22.\u003c/li\u003e\n\u003cli\u003eSchultz, R.M.; Zwingenberger, A. Radiographic, computed tomographic, and ultrasonographic findings with migrating intrathoracic grass awns in dogs and cats. Vet. Radiol. Ultrasound 2008, 49, 249\u0026ndash;255.\u003c/li\u003e\n\u003cli\u003eStillion JR, Letendre JA. A clinical review of the pathophysiology, diagnosis, and treatment of pyothorax in dogs and cats. J Vet Emerg Crit Care2015;25(1):113\u0026ndash;29.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"veterinary-research-communications","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"verc","sideBox":"Learn more about [Veterinary Research Communications](https://www.springer.com/journal/11259)","snPcode":"11259","submissionUrl":"https://submission.nature.com/new-submission/11259/3","title":"Veterinary Research Communications","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Foreign body, foxtail, surgery, ultrasonography, feline","lastPublishedDoi":"10.21203/rs.3.rs-7762463/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7762463/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eMigrating grass awns are a rare cause of thoracic reactions in cats, resulting in pleural effusion, inflammation, and granulomatous responses. Diagnosis and localization are challenging, and treatment commonly requires invasive surgical intervention.\u003c/p\u003e\u003cp\u003eWe report a case of a 5-year-old, neutered male, domestic shorthair cat referred for pleural effusion and suspected intrathoracic vegetal foreign body. Thoracic ultrasonography confirmed the presence of pleural effusion and a linear hyperechoic structure within the pleural space was visualized. An ultrasound-guided minimally invasive thoracotomy was performed through the right fifth intercostal space and intraoperative ultrasonography was useful to precisely locate and remove the foreign body using a Hartmann ear forceps. Cytological analysis was performed on the pleural fluid and bacteriological analysis was performed on both the pleural fluid and the retrieved foreign body. The cytologic findings were consistent with an exudative effusion but no bacteria were isolated on both direct and enrichment bacterial cultures; empirical antibiotic treatment with marbofloxacin was continued. The patient recovered uneventfully, and follow-up revealed complete resolution of the clinical signs.\u003c/p\u003e\u003cp\u003eThis case report highlights the effectiveness of ultrasound-guided minimally invasive approach for intrathoracic vegetal foreign body removal in a cat. The transthoracic and intraoperative ultrasound can be useful for visualization and exact localization of the grass awn, minimizing surgical trauma and improving the outcome.\u003c/p\u003e","manuscriptTitle":"Ultrasound-guided minimally invasive thoracotomy for removal of migrating grass awn in a cat","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-10-17 02:09:17","doi":"10.21203/rs.3.rs-7762463/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-11-17T22:20:22+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-11-17T19:07:09+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-11-10T10:57:32+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"184291654339584584917202633306595842932","date":"2025-11-02T16:51:01+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-11-01T19:30:32+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"229289717054971319535985231652344909015","date":"2025-11-01T09:46:12+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"13308832236427538268297637021227592859","date":"2025-10-08T13:33:36+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-10-03T08:54:49+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-10-03T04:43:58+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-10-03T04:42:46+00:00","index":"","fulltext":""},{"type":"submitted","content":"Veterinary Research Communications","date":"2025-10-01T21:14:23+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"veterinary-research-communications","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"verc","sideBox":"Learn more about [Veterinary Research Communications](https://www.springer.com/journal/11259)","snPcode":"11259","submissionUrl":"https://submission.nature.com/new-submission/11259/3","title":"Veterinary Research Communications","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"58b879f7-a8a0-4e18-9146-fb49f653cc02","owner":[],"postedDate":"October 17th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2026-01-26T16:05:59+00:00","versionOfRecord":{"articleIdentity":"rs-7762463","link":"https://doi.org/10.1007/s11259-026-11072-z","journal":{"identity":"veterinary-research-communications","isVorOnly":false,"title":"Veterinary Research Communications"},"publishedOn":"2026-01-20 15:59:08","publishedOnDateReadable":"January 20th, 2026"},"versionCreatedAt":"2025-10-17 02:09:17","video":"","vorDoi":"10.1007/s11259-026-11072-z","vorDoiUrl":"https://doi.org/10.1007/s11259-026-11072-z","workflowStages":[]},"version":"v1","identity":"rs-7762463","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7762463","identity":"rs-7762463","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}