Biomechanical comparison of compact versus standard flute drill bits, and interlocking versus buttress thread self-tapping cortical bone screws in cadaveric equine third metacarpal condyle.

OBJECTIVES: To compare (1) performance of compact versus standard flute drill bits, (2) screw insertion properties and (3) pullout variables between interlocking thread (ITS) and buttress thread (BTS) self-tapping screws in third metacarpi. STUDY DESIGN: In vitro experimental study. SAMPLE POPULATION: Paired third metacarpi from 11 Thoroughbreds aged 2-4 years. METHODS: Screws were inserted into the lateral condylar fossae following bone preparation using the respective drill bit for each screw type. Screw pullout was achieved using a mechanical testing system. Density and porosity of bone surrounding screw holes was measured with microcomputed tomography following each pullout test. Drilling, screw insertion and pullout variables were compared between drill bit and screw types using repeated measures ANOVA. Linear regression analyses were used to characterize relationships between bone tissue properties and drill bit and screw outcomes. RESULTS: Maximum torque power spectral density (PSD) was lower for compact flute drill bits. Insertion torque was 50% higher for ITS. BTS had 33% greater preyield stiffness and 7% greater mean yield force. Bone tissue properties affected measured variables similarly for both screw and drill bit types. CONCLUSIONS: Lower torque PSD may increase durability of the compact flute drill bit. ITS had greater insertional torque, which may reflect greater bone engagement. BTS had greater resistance to axial pullout forces. CLINICAL SIGNIFICANCE: Metacarpal bone provides a simple model for comparison of drill bit and screw designs. Use of ITS to repair equine fractures subject to predominantly tensile forces is not justified based on the results of this study.

Comparison of skeletal scintigraphy and standing 18 F-NaF positron emission tomography for imaging of the fetlock in 33 Thoroughbred racehorses.

This retrospective, methods comparison study aimed to compare skeletal scintigraphy and 18 F-NaF positron emission tomography (PET) for the detection of abnormalities in the fetlocks of Thoroughbred racehorses. Thirty-three horses (72 limbs) imaged with both scintigraphy and 18 F-NaF PET, for investigation of lameness or poor performance related to the fetlock, were included. Seven observers, including experienced racetrack practitioners, surgery and imaging residents, and a board-certified veterinary radiologist, independently reviewed all data for evidence of increased radiopharmaceutical uptake in 10 different regions of interest. The interobserver agreement was higher for PET (Kappa-weighted (K-w) 0.73 (0.51-0.84)) (median (range)) than for scintigraphy (0.61 (0.40-0.77)) (P < 0.0001). When scintigraphy and PET were compared, the agreement was fair (K-w 0.29). More sites of increased uptake were identified using PET compared with scintigraphy. Agreement between the two modalities was higher for the palmar/plantar metacarpal/metatarsal condylar regions (K-w 0.59) than for the proximal sesamoid bones (K-w 0.25). Increased radiopharmaceutical uptake was detected in the medial proximal sesamoid bone in 6.9% and 22.2% of limbs with scintigraphy and PET, respectively. The high interobserver agreement for PET, despite the recent introduction of this technique, demonstrates the ease of clinical interpretation of PET scans. The higher number of lesions detected with PET compared with scintigraphy can be explained by the higher spatial resolution and cross-sectional nature of this modality. Study findings supported using PET in a clinical population of racehorses, in particular for the assessment of the proximal sesamoid bones.

Longitudinal monitoring of fetlock lesions in Thoroughbred racehorses using standing 18F-sodium fluoride positron emission tomography.

OBJECTIVE: To assess the repeatability of equine 18F-sodium fluoride (18F-NaF) positron emission tomography (PET) findings, and to evaluate the ability of PET to monitor the progression of areas of increased radiopharmaceutical uptake (IRU) in the fetlocks of Thoroughbred racehorses. ANIMALS: 25 racehorses with clinical signs related to fetlock injuries. PROCEDURES: This study is a prospective, longitudinal clinical study. Twenty-five racehorses (54 fetlocks) underwent three 18F-NaF PET scans 6 weeks apart. The first 18F-NaF PET scan was performed at the start of a 12-week period of rest from racing (lay-up). Areas of IRU in the fetlock joints were quantified using maximal standardized uptake values (SUVmax) and were graded by 2 experienced observers. Statistical comparisons were made between scans to detect changes in IRU grade and SUVmax over time. RESULTS: Standing PET findings were repeatable, with 131/149 (88%) areas of IRU identified on the initial scans seen again at the 6-week follow-up scan. The palmar/plantar condyles were the sites most commonly presenting with IRU, followed by the proximal sesamoid bones. Overall, 65% of fetlocks demonstrated improvement in IRU grade during the 12-week period of rest from racing. Areas of higher IRU grade took longer to resolve than the lower graded areas. CLINICAL RELEVANCE: Standing PET findings in the racehorse fetlock were repeatable. The SUV-based grading system may be helpful when determining appropriate lay-up duration for Thoroughbred racehorses. PET may be used to monitor areas of the fetlock involved in catastrophic breakdown injuries in Thoroughbred racehorses.

Osteochondral necrosis of the femoral condyles in Thoroughbred foals: eight cases (2008-2018).

OBJECTIVE: To describe clinical, imaging, gross, and histopathological abnormalities associated with osteochondral necrosis of the femoral condyles in foals and identify features suggestive of a common pathogenesis. ANIMALS: 8 Thoroughbred foals euthanized with a presumptive diagnosis of necrosis of the femoral condyles. PROCEDURES: Postmortem CT was performed on all distal femoral epiphyseal samples. The articular epiphyseal cartilage complex (AECC) of affected distal femurs was examined grossly and histologically, focusing on lesions of interest identified on CT images. RESULTS: 7 foals were between 9 and 23 days old at the time of euthanasia; 1 foal was 85 days old. Concurrent illness (neonatal maladjustment syndrome, neonatal isoerythrolysis, or infection such as enteritis and omphalitis) was diagnosed in 7 foals. The characteristic antemortem radiographic and postmortem CT finding was a crescent-shaped osteochondral flap displaced from the affected medial femoral condyle. Synovial fluid cytology from affected joints was either within normal limits or consistent with mild inflammation. Histologically, all lesions were characterized by osteochondral necrosis and detachment of the AECC. In 6 foals, polymorphonuclear cells were found within growth cartilage canals, representing septic cartilage canals. CLINICAL RELEVANCE: Osteochondral necrosis was interpreted to be secondary to bacterial colonization of the distal femoral AECC, evidenced by septic cartilage canals identified in 6 of 8 foals. This uncommon condition was previously thought to arise from an ischemic event, but the disease process was not well understood. An improved understanding of the pathogenesis of osteochondral necrosis is the first step in formulating more successful preventative and treatment strategies.

Isolation of Campylobacter fetus subspecies fetus from an abdominal abscess in an adult mare.

A 12-year-old Warmblood mare was referred for evaluation of behavioral changes not explained by general physical examination or lameness evaluation. Transrectal ultrasound examination was performed to determine if the behavioral changes were related to ovarian abnormalities, and a large abscess was found near the base of the cecum. Laparoscopic-guided aspiration and lavage of the abscess cavity followed by injection of benzyl penicillin G was carried out. Culture of the lavage sample yielded Campylobacter fetus subspecies fetus, an organism not previously reported as an etiological agent in abdominal abscesses in horses. The mare was treated after surgery with an extended course of antibiotics (minocycline per os q12h for 10 days followed by enrofloxacin per os q24h for 42 days). The mare resumed work in competitive eventing 10 months after surgery, and the behavioral complaints had resolved according to the owner. Key clinical message: We describe the diagnosis and treatment of a mare with an abdominal abscess from which Campylobacter fetus subspecies fetus was cultured. This organism has not previously been reported as an etiological agent in abdominal abscesses in horses.

Isolement de Campylobacter fetus sous-espèce fetus d'un abcès abdominal chez une jument adulte. Une jument Warmblood âgée de 12 ans fut référée pour évaluation de changements de comportement non-expliqués par un examen physique général ou une évaluation de boiterie. Un examen échographique transrectal fut effectué afin de déterminer si les changements de comportement étaient reliées à des anomales ovariennes et un large abcès fut trouvé près de la base du caecum. Une aspiration guidée par laparoscopie et un lavage de la cavité de l'abcès suivis d'une injection de benzyle pénicilline G furent effectués. Une culture de l'échantillon de lavage permis d'identifier Campylobacter fetus sous-espèce fetus, un organisme n'ayant pas été rapporté antérieurement comme agent étiologique dans les abcès abdominaux chez les chevaux. La jument fut traitée après la chirurgie avec un régime prolongé d'antibiotiques (minocycline per os q12h pour 10 jours suivi d'enrofloxacine per os q24h pour 42 jours). La jument recommença à travailler dans des compétitions 10 mois après la chirurgie et les plaintes concernant le comportement étaient résolues selon le propriétaire.Message clinique clé:Nous décrivons le diagnostic et le traitement d'une jument avec un abcès abdominal à partir duquel on isola C. fetus sous-espèce fetus. Cet organisme n'a pas été rapporté antérieurement comme agent étiologique dans les abcès abdominaux chez les chevaux.(Traduit par Dr Serge Messier).

Scapula fracture secondary to metastatic pulmonary carcinoma in a horse: Clinical, sonographic, radiographic, computed tomographic, and pathologic findings.

A 20-year-old Quarter horse gelding was referred for evaluation of an acute onset non-weight-bearing right forelimb lameness. Marked soft tissue swelling was apparent over the right scapula and shoulder region; no crepitus was palpable. A complete transverse fracture of the scapular neck was suspected based on ultrasonography and radiographs were obtained to confirm the presumptive diagnosis. A complete, oblique fracture of the right scapular neck with mild cranial and proximal displacement of the distal fragment was detected. Computed tomography of the upper right forelimb was performed post-mortem; lytic bony destruction of the scapular neck with a secondary pathologic fracture was observed. The lesion was considered most likely neoplastic. At necropsy a complete, comminuted fracture of the right scapula was confirmed, secondary to neoplastic invasion of the bone. A solitary, dorsally located, neoplastic mass was also observed within the parenchyma of the right caudal lung. Histopathologically, the lung and scapula lesions were similar, characteristic of a well-differentiated pulmonary carcinoma.

Fracture de l'omoplate secondaire à un carcinome pulmonaire métastasique chez un cheval : trouvailles cliniques, échographiques, radiographiques, par tomodensitométrie et pathologiques. Un cheval hongre Quarter horse âgé de 20 ans fut référé pour évaluation d'une boiterie de non-appui de la patte avant droite d'apparition aiguë. Une enflure marquée des tissus mous était apparente par-dessus l'omoplate droite et la région de l'épaule; aucun crépitement n'était palpable. Une fracture transverse complète du col de l'omoplate était suspectée sur la base de l'échographie et des radiographies furent obtenues pour confirmer le diagnostic présomptif. Un examen par tomodensitométrie de la portion supérieure du membre droit fut effectué post-mortem; une destruction osseuse lytique du col de l'omoplate avec une fracture pathologique secondaire fut observée. La lésion fut considérée comme fort probablement néoplasique. Lors de la nécropsie, une fracture comminutive complète de l'omoplate droite fut confirmée, secondaire à l'invasion néoplasique de l'os. Une masse néoplasique solitaire, localisée dorsalement fut également observée dans le parenchyme du poumon caudal droit. À l'examen histopathologique, les lésions du poumon et de l'omoplate étaient similaires, caractéristiques d'un carcinome pulmonaire bien différencié.(Traduit par Dr Serge Messier).

Preoperative factors associated with resection and anastomosis in horses presenting with strangulating lesions of the small intestine.

OBJECTIVE: To determine if preoperative and intraoperative clinical variables correlate with resection and anastomosis (RA) in horses presenting with strangulating small intestinal (SI) lesions. STUDY DESIGN: Retrospective case series. ANIMALS: Horses undergoing exploratory celiotomy for a strangulating SI lesion (n = 243). METHODS: The records of horses undergoing surgical correction for strangulating SI lesions from January 1, 2000 to December 31, 2017 were reviewed. Horses were categorized as treated with RA or not treated with RA. Obtained information included history, signalment, clinical findings, diagnostic test results, intraoperative findings, and survival to discharge. Univariable and multivariable analyses were used to compare data between horses treated with RA vs those not treated with RA (P = .05). RESULTS: In total, 172 SI lesions were resected, and 71 were not resected. Horses that had gastric reflux at admission to the hospital (odds ratio [OR] 5.56; 95% CI 1.76, 17.59) and horses with amotile SI according to abdominal ultrasonography (OR 9.69; 95% CI 3.09, 30.37) were more likely to undergo RA. Increased difference between peritoneal fluid and blood lactate was higher in horses that underwent RA (OR 1.55; 95% CI 1.12, 2.13). Survival to hospital discharge was lower in the group of horses that underwent RA compared with horses that did not undergo RA. CONCLUSION: Resection and anastomosis of strangulating SI lesions was associated with several preoperative variables. CLINICAL SIGNIFICANCE: This study highlights the value of preoperative diagnostic procedures in aiding intraoperative decision making and prognostication in horses presenting with strangulating SI lesions.