Retrospective evaluation of the effects of a single intraoperative dose of dexamethasone in horses undergoing exploratory laparotomy for small intestinal lesions (2008-2019): 240 cases.

OBJECTIVE: To determine the effect of a single intraoperative dose of dexamethasone on the risk of postoperative reflux (POR) in horses undergoing small intestinal surgery and to investigate its association with incisional complications and short-term survival. DESIGN: Retrospective cohort study over an 11-year period (2008-2019). SETTING: UK-based private referral center. ANIMALS: Two hundred and forty client-owned horses >6 months of age undergoing exploratory laparotomy for treatment of a small intestinal lesion. INTERVENTIONS: Ninety-seven horses received a single intraoperative dose of dexamethasone (0.1 mg/kg, IV). MEASUREMENTS AND MAIN RESULTS: Of 97 horses that received dexamethasone, 52 (53.6%) required small intestinal resection. Of 143 horses that did not receive dexamethasone, small intestinal resection was performed in 78 (54.5%). A total of 70 horses (29%) developed POR. There was no difference in the risk of POR between horses that received dexamethasone (25/97; 26%) and those that did not (45/143; 31%, P = 0.34). Risk factors associated with the development of POR included small intestinal resection (odds ratio [OR]: 4.55, 95% confidence interval [CI]: 2.27-9.11, P < 0.001), a PCV >40% 24 hours postoperatively (OR: 4.11, 95% CI: 2-8.45, P < 0.001), and a WBC count >10 × 109/L on admission (OR: 3.29, 95% CI: 1.47-7.41, P = 0.004). Dexamethasone was not associated with the odds of POR. Horses undergoing repeat laparotomy had a higher risk of incisional infection (OR: 8.07, 95% CI: 1.98-32.81, P = 0.004). Dexamethasone administration was not associated with incisional infection. The development of POR was negatively associated with short-term survival (OR: 0.07, 95% CI: 0.03-0.17, P ≤ 0.001). Dexamethasone administration was not retained in the final multivariable model for survival. CONCLUSIONS: Intraoperative dexamethasone was not associated with the development of POR in this study population, nor did it have an effect on postoperative survival or incisional infection in horses undergoing surgical management of small intestinal disease.

Antibiotic usage in 14 equine practices over a 10-year period (2012-2021).

BACKGROUND: Monitoring antibiotic usage is an important part of tackling antimicrobial resistance. The use of computerised records for monitoring has been previously described in the equine sector but there is currently no consensus on metrics used to report usage. OBJECTIVES: To document antibiotic use in equine practices in the United Kingdom over a 10-year period using commercially available practice management software. STUDY DESIGN: Retrospective survey. METHODS: A custom antibiotic usage report was created using Eclipse® practice management software. Participating practices were given instructions on how to generate the usage report. Annual reports were requested for a 10-year period (2012-2021 inclusive). Each report provided sales of each class of antibiotic in total mg and in mg/kg, based on the number of equids treated (for any transaction) and their average weight. The defined daily dose for animals (DDDvet) and the DDD/1000 (used in people) were also calculated to correct for variation in dosage rates between antibiotics. RESULTS: Fourteen practices submitted data for an annual maximum of 107 977 horses. Overall, median annual antibiotic usage was 54.25 mg/kg (range 45.34-60.27 mg/kg), 1.52 defined daily doses/animal/year (range 1.39-1.70) and 4.17 defined daily dose/1000 animals (range 3.82-4.66). Overall median highest priority critically important antimicrobial usage was 0.67 mg/kg (range 0.56-1.71), 0.12 defined daily doses/animal/year (range 0.10-0.14) and 0.33 defined daily dose/1000 animals (range 0.29-0.39). MAIN LIMITATIONS: The software relied on the accurate identification of antibiotic preparations. The calculation of DDDvet was complicated by the varying dose rates of antimicrobials used in equine practice. CONCLUSIONS: A reliable technique to measure antibiotic usage is presented. Defined daily dosage calculations may be more helpful in equine practice due to the preponderance of potentiated sulphonamides usage. These data and methods may provide the basis for future clinical audits aiming to enhance antimicrobial stewardship.

Presence and size of synovial masses within the navicular bursa correlate well between magnetic resonance imaging and bursoscopy and have a guarded prognosis.

BACKGROUND: Focal hyperintense lesions within the navicular bursa emanating from the dorsal border of the deep digital flexor tendon (DDFT) can be recognised on T1-weighted magnetic resonance images (MRI) and have been attributed to lameness in horses. Removal of these lesions, also referred to as synovial masses, by navicular bursoscopy is currently recommended. OBJECTIVES: To investigate the correlation between MRI and navicular bursoscopic findings. It is hypothesised that the prognosis following surgery is proportional to the size of the DDFT lesion. STUDY DESIGN: Retrospective analysis of clinical records. METHODS: Horses undergoing standing low-field MRI and navicular bursoscopy with >1 year follow-up were included. A grading system was developed to classify the size of synovial mass(es) and lesion(s) of the DDFT on MRI and at surgery. Generalised estimating equations were used to evaluate the association between MRI findings and surgery and between outcome and severity of the tendon injury. RESULTS: Fifty-nine horses presenting over a 15-year period (2006-2021) fulfilled inclusion criteria. Ninety navicular bursae were examined both on MRI and endoscopically. There was strong correlation between the size of synovial masses and tendon lesions on MRI and bursoscopy (p < 0.001, OR: 25.61, 95% CI 8.71-75.29 and p < 0.001, OR: 7.34, 95% CI 2.70-19.92, respectively). Size of tendon lesion and synovial mass had no impact on prognosis (p = 0.3, OR: 1, 95% CI 1-1 and p = 0.1, OR: 1, 95% CI 1-1, respectively), which was guarded (30.5% return to previous level of exercise). MAIN LIMITATIONS: Performance data for conservatively treated horses with MRI-detected synovial masses was not considered, nor was the effect of navicular bursal effusion. Horses were not randomly assigned to treatment protocols. CONCLUSION: There is good correlation between MRI and bursoscopic findings of DDFT lesions and synovial masses within the navicular bursa, with no false positives. Size of the synovial masses and DDFT lesions does not influence prognosis following navicular bursoscopy.

Caecal dysfunction following standing surgical procedures.

The aim of this study is to report cases of caecal dysfunction following surgical procedures in the standing horse. The study design is retrospective. Six client-owned horses developed caecal dysfunction following a variety of surgical procedures undertaken in the standing sedated horse. Medical records were reviewed for caecal dysfunctions that had occurred in horses within 2 weeks of standing surgical procedures. Signalment, details of the original standing surgery and medications administered were recorded. Short-term outcome was obtained from clinical records. Long-term outcome was obtained by telephone questionnaire with the owner. Six horses were identified to have developed caecal dysfunction following standing surgery for tooth extraction, laparoscopic ovariectomy, laparoscopic cryptorchidectomy, fracture repair, melanoma removal and castration. Three horses were euthanised with caecal perforation at the time of diagnosis. Three underwent surgical treatment (typhlotomy, decompression and caecal bypass by ileocolostomy). All three horses were alive post-operatively (follow-up at 2, 12 and 24 months). Caecal dysfunction may develop following surgical procedures performed under standing sedation. Careful post-operative monitoring and early identification of caecal dysfunction, and consequent potential need for surgical intervention, are important to optimise outcomes and minimise the risk of fatal caecal perforation occurring.

Arthroscopic removal of palmar intermediate carpal bone fracture fragments in four horses using a transthecal approach through the carpal flexor tendon sheath.

OBJECTIVE: To describe the removal of palmar intermediate carpal bone (ICB) fracture fragments using a transthecal approach through the carpal flexor tendon sheath. STUDY DESIGN: Case series. ANIMALS: Four horses with fractures of the palmar aspect of the ICB. METHODS: Two horses were injured when falling and two during recovery from general anesthesia. Three horses underwent MRI to supplement conventional imaging. Three horses had concurrent fractures of the radial and/or accessory carpal bones. Conventional proximolateral carpal sheath arthroscope and instrument portals were used, supplemented with a medial instrument portal through the carpal flexor retinaculum to access the palmar carpal ligament. Optimized dissection through the latter was facilitated by needle guidance and radiography. The fragment was dissected from the soft tissue attachments and the palmar ICB fragments retrieved through the carpal sheath in all horses. Surgery time was 85 to 142 min. RESULTS: Limitations of this technique include a long surgery time and the potential for hemorrhage to impair visibility during surgery. All four horses were discharged 3 to 8 days postoperatively. Three horses returned to full athletic work within 9 months postoperatively and one horse was euthanized due to persistent lameness. CONCLUSION: A tenoscopic transthecal carpal flexor tendon sheath approach provides access for removal of palmar ICB fracture fragments but should be viewed as an advanced arthroscopic procedure. CLINICAL SIGNIFICANCE: A transthecal approach through the carpal flexor tendon sheath offers an alternative technique for removal of palmar ICB fracture fragments.

A retrospective multicenter study on the use of locking compression plates for scapulohumeral arthrodesis in small equids.

OBJECTIVE: To report on technical aspects and outcomes after scapulohumeral arthrodesis (SHA) with a locking compression plate (LCP) in small equids. STUDY DESIGN: Retrospective multicenter case series. ANIMALS: Client-owned Shetland Ponies, Miniature Shetlands, and American Miniature Horses (n = 15). METHODS: Inclusion criteria were completed SHA with an LCP to treat scapulohumeral osteoarthritis/subluxation and availability of postoperative radiographs. Contributing surgeons completed a questionnaire to collect data. All radiographs were reviewed for this study. Follow-up information was obtained via re-admission to the hospital or telephone interview of the referring veterinarian or owner. Outcome was subjectively scored as excellent, good, moderate, or poor based on lameness and function. RESULTS: Sixteen SHAs were performed in 15 equids (body weight 65-145 kg) by nine different surgeons. A narrow 4.5/5.0 mm LCP (7-16 holes) was used in 14 of the 16 SHAs. Follow-up was collected 2.5 years after surgery (median; range: 9 weeks to 10 years). Major complications related to the SHAs were noted in 4 of the 13 horses alive long term, consisting of implant failure (n = 1), surgical site infection (n = 2), and scapular fracture (n = 1). The outcome was graded as excellent in 4, good in 5, and moderate in 4 horses. Two ponies were euthanized because scapulohumeral osteoarthritis and subluxation developed in the contralateral limb. CONCLUSION: Although major complications occurred in about one-third of ponies, SHA with LCP led to long-term survival with good function in most ponies. CLINICAL SIGNIFICANCE: SHA with an LCP offers a high chance for good long-term outcome in small equids although contralateral disease may affect outcome.

Outcome following repair of 63 sagittal fractures of the proximal phalanx in UK Thoroughbreds using either a triangular or linear screw configuration.

BACKGROUND: A triangular screw configuration has been suggested as preferable for repair of sagittal fractures of the proximal phalanx. OBJECTIVE: To assess the outcome of a triangular screw construct for repair of incomplete and complete minimally displaced proximal phalanx fractures under standing sedation in a population of Thoroughbred racehorses, compared with a cohort repaired using a linear screw configuration. STUDY DESIGN: Retrospective cohort study. METHODS: Medical records and radiographs were accessed to garner clinical data. Date of return to racing was determined from www.racingpost.com. Survival data were compared using log-rank test. RESULTS: Sixty-two horses with one horse having two separate fractures. Fifty-four fractures were repaired using triangular screw configuration, 10 with a linear screw configuration. 81% (43/53) of horses with triangular repair returned to racing at a median of 289 days (161-482 days), 70% (7/10) horses with linear screws returned to racing at a median of 351 days (230-815 days). MAIN LIMITATIONS: A limited number of horses underwent conventional (linear) screw placement. CONCLUSION: A triangular screw configuration placed in the standing sedated horse is an effective way to repair incomplete and complete minimally displaced proximal phalanx fractures. The rate of return to racing was excellent with a low rate of complications.

An alternative arthroscopic approach to the caudal pouches of the equine lateral femorotibial joint.

BACKGROUND: Current arthroscopic approaches to the caudal pouches of the lateral femorotibial joint are challenging and risk iatrogenic nerve and cartilage injury. OBJECTIVE: Describe an alternative arthroscopic approach to the caudal pouches of the lateral femorotibial joint in the horse and report intra-articular abnormalities observed during diagnostic stifle arthroscopy of these pouches. STUDY DESIGN: Descriptive cadaver anatomical and clinical study. METHODS: An approach to the caudal pouches of the lateral femorotibial joint was developed during clinical surgery using an arthroscopic portal in the popliteal tunnel of the femorotibial joint. Relevant anatomy of the lateral femorotibial joint was reviewed and the arthroscopic landmarks validated on 19 cadaver limbs. The procedure was then incorporated as part of routine inspection of 38 joints in 33 horses. RESULTS: Entry and examination of both pouches of the caudal lateral femorotibial joint was consistently achieved using an arthroscopic portal immediately cranial to the lateral collateral ligament in both cadaver and clinical limbs, with no adverse effects noted in the latter. Contrary to published descriptions, the division of the pouches was principally formed by a meniscopopliteal septum derived from the joint capsule in all cases, rather than the popliteus muscle and tendon as previously described. Abnormalities were detected in five cases. The finding of bilateral tearing within the popliteus muscle may represent a previously unrecognised arthroscopic condition. MAIN LIMITATION: Limited case numbers. CONCLUSION: An arthroscopic portal immediately cranial to the lateral collateral ligament permitted consistent entry into the popliteal tunnel and both pouches of the caudal lateral femorotibial joint.

Ceratohyoidectomy in standing sedated horses.

OBJECTIVE: To investigate the feasibility and complications associated with ceratohyoidectomy (CHE) in standing sedated horses unaffected (experimental horses) and standing sedated horses affected (clinical cases) with temporohyoid osteoarthropathy (THO). STUDY DESIGN: Case series. ANIMALS: Six experimental horses and four clinical cases. METHODS: Standing CHE was performed in six experimental horses euthanized 30 minutes (n = 3) and 7 days (n = 3) postoperatively. The four clinical cases were presented because of central facial nerve paralysis (n = 3), vestibular ataxia (n = 3), auricular hemorrhage (n = 2), quidding (n = 1), and oesophageal impaction (n = 1). Evolution was assessed by clinical examination during hospitalization and later by telephone interviews for the clinical cases. RESULTS: The procedure was successfully performed in all horses. Experimental horses did not show any short-term postoperative complications. Hemorrhage was experienced intraoperatively in one of the clinical cases and was successfully managed with placement of hemostatic forceps. Vestibular ataxia and other symptoms of THO improved within days, but facial nerve paralysis did not improve until 9 days to 6 months after surgery. Follow-up ranged from 9 to 24 months. All clinical cases returned to performance, and client satisfaction was excellent. CONCLUSION: Ceratohyoidectomy was consistently feasible in standing sedated horses. The method did not result in postoperative complications and led to resolution of clinical signs associated with THO. CLINICAL SIGNIFICANCE: Standing CHE should be considered in horses affected with THO, especially when horses present with marked vestibular deficits and ataxia, to reduce risks associated with recovery from general anesthesia.

Conservative versus surgical treatment of 21 sports horses with osseous trauma in the proximal phalangeal sagittal groove diagnosed by low-field MRI.

OBJECTIVE: To compare the outcome following conservative vs surgical management of sports horses with a diagnosis of subchondral bone trauma of the proximal aspect of the proximal phalanx (PP) by low-field MRI. STUDY DESIGN: Retrospective case series. ANIMALS: Twenty-one mature sports horses with evidence of high water signal within the proximal sagittal groove of the PP according to low-field MRI of the fetlock, with no definitive radiographic evidence of fracture. METHODS: Medical records (2010-2017) of horses admitted to 2 referral hospitals were reviewed. Historical, clinical, radiographic, and MRI findings and treatment choice were recorded. Conservative management consisted of confinement to a stall followed by gradual reintroduction to exercise. Surgical management consisted of cortical screw fixation across the proximal aspect of the PP. Long-term outcome was determined by telephone questionnaire or by clinical records review. Fisher's exact test was used to compare outcome between the 2 treatment groups. RESULTS: Follow-up was available in 17 of 21 horses in the study, including 8 horses treated conservatively and 9 treated surgically. No difference in outcome was detected in this study; 4 of 8 horses were sound after conservative management, and 5 of 9 horses were sound after surgery (P > .99). CONCLUSION: Approximately half of the horses that had a diagnosis of osseous trauma within the proximal aspect of PP returned to athletic activity, regardless of conservative or surgical management. CLINICAL SIGNIFICANCE: The prognosis for return to athletic functions in horses with osseous trauma within the proximal aspect of the PP is guarded.

Attempted medical management of suspected ascending colon displacement in horses.

OBJECTIVE: To determine the success of medical management of suspected displacement of the ascending (large) colon in horses. STUDY DESIGN: Retrospective case series. ANIMALS: Horses (n = 127) with suspected large colon displacement. METHODS: Medical records (January 1998-September 2008) of horses admitted for colic were reviewed. Suspected large colon displacement was diagnosed from clinical examination and in some cases, subsequent surgical examination. Medically managed horses were exercised and administered intravenous fluids and analgesia. Horses with suspected left dorsal displacement (LDD) of the large colon were also administered phenylephrine. RESULTS: Medical management had a high success rate for treatment of suspected right dorsal displacement (RDD) (64%) and LDD (76%) of the large colon; 4 horses died (1) or were euthanatized (3) and 36 horses had surgery. Of 127 horses treated medically or surgically for a colon displacement, 94% survived to hospital discharge. CONCLUSIONS: Horses with suspected RDD or LDD of the large colon may respond to medical management including exercise.

Osteomyelitis and osteonecrosis after intraosseous perfusion with gentamicin.

OBJECTIVE: To describe and discuss previously unreported complications associated with intraosseous perfusion with gentamicin in horses. STUDY DESIGN: Case report. ANIMALS: Ten-year-old Warmblood gelding. METHODS: Intraosseous perfusion with gentamicin into the proximal phalanx (P1) was used as part of the treatment regimen for distal interphalangeal joint and navicular bursa synovial sepsis. Although the sepsis responded favorably complications developed at the perfusion site, including persistent osteomyelitis, progressive osteonecrosis, and ultimately pathologic fracture of P1. RESULTS: The progression of the clinical signs and findings at necropsy are suggestive of a toxic osteonecrosis secondary to intraosseous perfusion. CONCLUSIONS: Further work is needed to investigate the effects of high dose gentamicin on equine mesenchymal cells that may be achieved during intraosseous perfusion. CLINICAL RELEVANCE: Lower doses of perfusate within the medullary canal of P1 or alternative perfusion sites should be considered.

The intra- and inter-assessor reliability of measurement of functional outcome by lameness scoring in horses.

The objective of this study was to assess the reliability of lameness scoring in horses. One veterinary surgeon examined nineteen lame horses on four occasions. Gait was recorded by camcorder, and scored from 0 to 10 ranging from sound to non-weight bearing lameness. A global score of overall change in lameness during the study was also determined for each horse. To measure intra-assessor reliability of the scoring systems, one veterinary surgeon scored videotapes of the horses' gaits on two occasions. To measure inter-assessor reliability, three veterinary surgeons viewed the videotapes, assigning individual lameness scores plus global scores to each horse. Reliability of individual lameness scoring was good intra-assessor, but only just within our acceptable limit inter-assessor. However, global scoring of change in lameness throughout the study was found to be reliable overall. Since clinician scoring is commonly used to assess lameness in horses, this is an important finding, fundamental to future clinical studies.