Alexandra L. Curtiss

INTRODUCTIONThe treatment of equine patients with angular limb and/or rotational deformities combined with closed physes presents a clinical challenge to equine practitioners. The report by Gaida et al in this issue outlines the management of one such case by utilizing a radial osteotomy for a deformity of the distal metacarpus. Although the authors had some challenges with the post-operative management, they did have an acceptable outcome with this technique.Osteotomies and ostectomies are uncommon surgical procedures used to treat angular and rotational limb deformities in patients beyond the time frame of growth retardation or in older patients that have acquired an angular limb deformity secondary to another pathology (healed fracture, osteoarthritis, or previous infection). The procedure involves transecting and possibly removing a portion of bone and stabilizing the resulting construct with implants to achieve a more anatomically appropriate limb. The most common anatomical location treated is the metacarpophalangeal/metatarsophalangeal joint or the diaphysis of MC3/MT3, followed by deformities of the carpal region, with the traumatic deformation of the carpal bones or the distal radius being the focus. Reports also exist of surgical correction of deformities involving the radial diaphysis (Auer, 2019).A thorough examination of the limb in question is necessary for surgical planning, including static and dynamic examination of the patient. Angular limb deformities can be complex with deformities in more than one plane and so a detailed understanding of the abnormality is fundamental for surgical success. Radiographs and computed tomographic examination of the affected area should be performed on all candidates. Three-dimensional printing combined with planning software can be valuable in assessing complicated deformities (Auer 2019, Auer 2022). When the abnormality involves only a simple deviation, the pivot point should be established based on pre-operative imaging, which is accomplished by drawing lines perpendicular to the joint surfaces proximal and distal to the deformity of the involved long bones and identifying the bisection point. The degree of deviation can then be calculated based on this point. In more complex cases, multiple pivot points may exist in different planes. These bisecting pivot points are used to determine the correction angle to be utilized intra-operatively. Identifying the complexity of the deformity as well as the planes involved will influence the surgical technique to be utilized. (Auer, 2019)

Objective: To describe the outcomes of arthroscopic debridement of third carpal bone (C3) incomplete slab fractures (ISF) in racehorses. Study design: Retrospective case study. Sample population: Horses undergoing arthroscopic debridement of ISF of C3. Methods: The medical records of horses surgically treated for ISF of C3 were reviewed. Age, sex, breed, limb, fracture configuration, preoperative radiographs, arthroscopic findings, postoperative intraarticular therapies, and exercise recommendations were recorded. Racing performance was obtained from online databases. Univariable analyses were used to determine associations between independent variables and outcomes. Results: A total of 33 horses fit the criteria. There were 19 Thoroughbreds and 14 Standardbreds. The postoperative racing rate was 66.7% (22/33 horses). There was no statistically significant difference in outcome between dorsal and sagittal fractures or breeds. There were no significant differences in earnings per start or total earnings before and after surgery. Several horses showed an increase in racing frequency and an increase in earnings post‐injury. Most horses, 81.8% (27/33), had at least one career start prior to undergoing surgery. The median convalescent period was 247.1 days. Conclusion: Early diagnosis and subsequent arthroscopic debridement of C3 ISF was a viable treatment approach with a favorable prognosis for racing postoperatively. Clinical significance: Early detection and arthroscopic debridement of ISF before progression to a complete slab fracture and/or subsequent osteoarthritis of the joint could improve athletic outcomes.

Background: Epiglottitis is an uncommon upper airway pathology manifested endoscopically by mucosal oedema, reddening and thickening of the epiglottic mucosa. Literature on epiglottitis in horses is sparse. Objectives: To describe the diagnosis, treatment and outcome of Thoroughbred and Standardbred racehorses diagnosed with epiglottitis at a single centre. A secondary objective is to demonstrate the efficacy of inhaled and topical anti‐inflammatories for this condition. Study Design: Retrospective case series. Methods: Medical records (2009–2023) were reviewed for racehorses treated for epiglottitis. Data collected included signalment, history, endoscopic findings, treatment progression, hospitalisation duration and any reason for re‐admission. Race records were obtained to determine days to first race, earnings and career length. Results: Twenty‐four horses were included in the study. Horses were referred for a variety of upper airway abnormalities including epiglottic entrapment, dysphagia and respiratory stridor. Of the horses admitted for epiglottic entrapment (18), a more accurate diagnosis of epiglottitis was made based on admission endoscopy. Horses were treated with systemic, topical and inhaled anti‐inflammatories, as well as topical and inhaled antimicrobials. Twenty‐two horses (91.6%) returned to racing after discharge. Eight horses (33.3%) were re‐admitted, including six for recurrent epiglottitis and two for other airway pathologies. Main Limitations: The major limitations include those inherent to a retrospective report. The results would be stronger with higher case numbers. Additionally, we did not have sufficient case numbers to compare outcomes of horses treated with inhaled medications versus those that were not. Racehorses inevitably develop other racing‐related problems which confound studies of this nature. Conclusions: Epiglottitis is a rare upper airway condition that is challenging to diagnose. However, when accurately identified, it can be successfully treated, offering a good prognosis for a return to athletic function.

Background: In anaesthetised horses, bradycardia secondary to high vagal tone can reduce cardiac output and blood pressure. The use of anticholinergics in horses is limited due to concerns about ileus and abdominal discomfort. This retrospective study sought to determine the prevalence of post‐operative abdominal discomfort in healthy horses that received atropine under isoflurane anaesthesia. Study design: A retrospective evaluation of 222 general anaesthesia events between January 2019 and December 2019 was undertaken. Methods: One hundred and eleven horses that received atropine were identified, and 111 case match controls that did not receive atropine were also selected. Information gathered from the medical records included signalment, anaesthetic drugs, surgical procedures, duration of anaesthesia and surgery, dobutamine and atropine administration, and the occurrence of abdominal discomfort for 24 h after anaesthesia. After initial data analysis, a second cohort of records was assessed separately. The horses in this group were castrated under general anaesthesia (with or without atropine; n = 68). Logistic regression models and Fisher's exact tests were used to look for factors contributing to abdominal discomfort post‐anaesthesia. The significance level was set to 5% ( p < 0.05). Results: Atropine administration was not associated with the development of post‐anaesthetic abdominal discomfort (OR = 2.121, 95% CI [0.767, 5.869]; p = 0.2). Overall, 18/222 (8.1%) incidences of abdominal discomfort were identified. All incidents occurred in colts undergoing castration. In a separate analysis of only horses anaesthetised for castration, atropine was associated with developing abdominal discomfort (OR = 3.143, 95% CI [1.082, 9.132]; p = 0.04). Discussion: Atropine was not associated with post‐operative abdominal discomfort except in colts undergoing castration. All episodes of discomfort were mild and resolved with minimal intervention. The potential impact of insufficient analgesia in horses undergoing castration is a confounding factor and requires prospective investigation. Conclusion: Overall, atropine at a dose of 0.006 mg/kg IV appears to be a safe method to treat bradycardia in otherwise healthy horses anaesthetised for orthopaedic and upper airway procedures. Further work is required to determine if atropine is safe for colts undergoing castration.

Summary: This case report describes the clinical presentation, surgical treatment, post‐operative management and outcome of a bronchocutaneous fistula with intrathoracic abscessation in a yearling horse. The animal was presented with a history of several months of persistent coughing and a cutaneous fistula located over the right ventral hemithorax. The yearling had purulent discharge similar in character from both nares and draining out of the fistula. A bronchocutaneous fistula with intrathoracic abscessation was diagnosed by endoscopic examination of the cutaneous fistula. The treatment initially consisted of cyanoacrylate applied topically to the affected bronchi under endoscopic guidance, which was not successful. The fistula was successfully sealed with a diode laser used to create local inflammation at the site. One week after the second intervention, the patient's clinical signs resolved and the fistula was completely sealed 10 weeks following intervention. Follow‐up at 16 months revealed that the patient was doing well and clinically normal.

Background: Epiglottitis is an uncommon upper airway pathology characterized by inflammation and swelling of the epiglottal mucosa and/or subepiglottal tissues. Only one report exists in the literature of epiglottitis in horses, which documents the diagnosis, treatment and prognosis of the condition. Objectives: To describe the evaluation, treatment, and outcome of thoroughbred and standardbred racehorses diagnosed with epiglottitis at our hospital. A secondary objective is to demonstrate the efficacy of inhaled and topical anti-inflammatories for this condition. Study design: Retrospective case series. Methods: Medical records (2009-2023) were reviewed for racehorses treated for epiglottitis. Data collected included signalment, history, endoscopic findings, treatment progression, hospitalization duration, and any reason for re-admission. Race records were obtained to determine days to first race, earnings, and career length. Horses were classified into three groups based on the severity of the epiglottitis. Results : Presenting complaint, interpretation of the endoscopic examination, treatment, progression and outcome were recorded. Of the 24 horses included, 16 were referred for surgical correction of epiglottic entrapment. Other reasons for referral included dysphagia and upper respiratory stridor. Horses were treated with systemic, topical and inhaled anti-inflammatories. Hospitalization ranged from 1 to 43 days. Time to first race ranged from 18 to 175 days. Twenty-two horses returned to racing; Eight horses were re-admitted, including six for recurrent epiglottitis and two for other airway pathologies. Main limitations : The major limitations include those inherent to a retrospective report. The results would be stronger with higher case numbers. Additionally, we did not have sufficient numbers to compare outcomes of horses treated with inhaled medications versus those that were not. Racehorses inevitably develop other racing-related problems which confound studies of this nature. Conclusions : Epiglottitis is an uncommon upper airway pathology that, when properly diagnosed, can be treated successfully with a good prognosis for return to athletic function.

Background: Subchondral bone pathology is common in Thoroughbred racehorses and believed to precede more serious injury. Early identification of pathology is critical to allow for intervention. Objectives: To determine interobserver variability of fetlock subchondral bone lesions using cone beam and fan beam computed tomography (CBCT, FBCT) and to validate a robotics‐controlled CBCT to identify fetlock subchondral bone pathology in the Thoroughbred racehorse. Study design: Prospective cohort study. Methods: FBCT and CBCT images were acquired of 25 metacarpo‐/metatarsophalangeal joints of Thoroughbred racehorses. Images were analysed for subchondral bone lesions commonly identified in Thoroughbred fetlocks by an imaging specialist and surgery specialist. Interobserver and intermodality equivalence were determined with a Pearson correlation analysis and Bland‐Altman equivalence test. Results: Interobserver FBCT correlation was significant ( P < .05) for 19 of 25 variables (Pearson R mean 0.77). Concordance was significant for all 25 variables (Bland Altman average difference 0.28 ± 0.21 mm). Interobserver CBCT correlation was significant for 21 of 25 variables (Pearson R mean 0.73). Concordance was significant for all variables (Bland Altman average difference 0.07 ± 1.90 mm). Intermodality (FBCT vs CBCT) correlation and concordance was significant for all variables as interpreted by the radiologist (Pearson R mean of 0.72, Bland Altman average difference 0.21 ± 0.47 mm). Intermodality correlation was significant for 19 of 25 variables as interpreted by the surgeon (Pearson R mean of 0.72). Concordance was significant for all variables (Bland Altman average difference 0.49 ± 0.52 mm). Main limitations: Neither FBCT nor CBCT images were compared with other imaging modalities/histopathology; limited number of cases included; inconsistent agreement of small lesions in specific categories. Conclusions: Standing CBCT is a valid diagnostic modality to identify subchondral bone lesions in Thoroughbred fetlocks. This technology may provide valuable information regarding the development and progression of fetlock pathology and yield insight into predisposing factors leading to more severe pathology.

Objective To report an epiglottopexy technique for the treatment of epiglottic retroversion (ER) in 2 horses. Study design Case report. Animals A 2‐year‐old thoroughbred gelding and a 6‐year‐old standardbred gelding, both with ER. Methods Epiglottic retroversion was diagnosed via exercising endoscopic examination in both horses. Epiglottopexy technique was performed in both cases. Results Both horses returned to previous racing class within 1 year after surgery. Repeat exercising endoscopy of 1 horse 6 months postoperatively revealed resolution of the ER. Conclusion Epiglottopexy should be considered for treatment of ER in the equine athlete. Clinical significance Previously reported surgical techniques for ER in the equine athlete have not resulted in horses returning to previous performance level. The technique reported here resulted in both horses achieving athletic status.