Condylar fracture location is correlated to exercise history in Thoroughbred racehorses.

BACKGROUND: Condylar fractures are a major cause of morbidity and mortality in Thoroughbred racehorses. Condylar fractures have a variety of fracture configurations that suggest there may be differences in aetiopathogenesis. OBJECTIVE: To determine if exercise history differs with condylar fracture location in a population of Thoroughbred racehorses. STUDY DESIGN: Retrospective analysis of clinical and exercise data. METHODS: Exercise history of Thoroughbred racehorses that had condylar fracture repair between 1 January 2018 and 28 February 2021 was compared between racehorses that had fractures located radiographically either within the parasagittal groove (PSG) or abaxial to the PSG (non-PSG). Age, sex, and last event (race, timed work) matched control groups were compared between the PSG and non-PSG groups. Additionally, exercise history variables of both groups were each compared with a group-specific control population, each consisting of three control racehorses of equivalent age and sex matched to each affected racehorse by last event (race or official timed work) before fracture. RESULTS: Eighty-two horses with 84 fractures (45 PSG, 39 non-PSG) met inclusion criteria. Age was not different between groups (PSG: 3.4 ± 1.3 years [mean ± SD], non-PSG: 3.7 ± 1.3, p = 0.3). Number of races (PSG: 5.3 ± 7.1, non-PSG: 11.4 ± 8.9, p < 0.001), total race furlongs (PSG: 38.2 ± 54.7, non-PSG: 79.2 ± 64, p = 0.003), and number of active days (PSG: 304 ± 224, non-PSG: 488 ± 314, p = 0.003) before fracture were greater; while mean number of layups was fewer (PSG: 1.0 ± 1.2, non-PSG: 0.5 ± 0.7, p = 0.02) in horses with non-PSG fracture. Horses with non-PSG fracture had more differences compared with their respective control group than horses with PSG fractures. Outcomes following fracture repair were not different between groups. MAIN LIMITATIONS: Retrospective study, one regional racehorse population, two-dimensional imaging and potential inherent bias for fracture localisation, low statistical power for return to performance analysis. CONCLUSIONS: Thoroughbred racehorses with non-PSG condylar fractures have a more extensive exercise history than horses with PSG condylar fractures, suggesting differences in fracture aetiopathogenesis.

CONTEXTO: Fraturas condilares são uma das principais causas de morbidade e mortalidade em cavalos de corrida puro­sangue inglês. As fraturas condilares apresentam uma variedade de configurações que sugerem que pode haver diferenças em suas etiopatogenia. OBJETIVO: Determinar se o histórico de exercícios difere com a localização da fratura condilar em uma população de cavalos de corrida puro­sangue inglês. DELINEAMENTO DO ESTUDO: Análise retrospectiva de dados clínicos e de exercício. MÉTODOS: O histórico de exercícios de cavalos de corrida puro­sangue inglês que tiveram reparo de fratura condilar entre 1 de janeiro de 2018 e 28 de fevereiro de 2021 foi comparado entre cavalos de corrida que tiveram fratura localizada radiograficamente dentro da ranhura parasagital (RPS) ou abaxial à RPS (não RPS). Os grupos foram pareados de acordo com a idade, sexo e último evento (corrida ou trabalho cronometrado) para comparação de RPS e não RPS. Além disso, as variáveis de histórico de exercícios de ambos os grupos foram comparadas a uma população de controle específica, cada uma consistindo em três cavalos de corrida de controle com idade e sexo equivalentes combinados com cada cavalo de corrida afetado pelo último evento (corrida ou trabalho cronometrado oficial) antes da fratura. RESULTADOS: Oitenta e dois cavalos com 84 fraturas (45 RPS, 39 não RPS) atenderam aos critérios de inclusão. A idade não foi diferente entre os grupos (RPS: 3,4 ± 1,3 anos (média ± DP), não RPS: 3,7 ± 1,3, p=0,3). O número de corridas (RPS: 5,3 ± 7,1, não RPS: 11,4 ± 8,9, p<0,001), furlongs totais de corrida (RPS: 38,2 ± 54,7, não RPS: 79,2 ± 64, p=0,003) e número de dias ativos (RPS: 304 ± 224, não RPS: 488 ± 314, p=0,003) antes da fratura foram maiores; enquanto o número médio de repousos foi menor (RPS: 1,0 ± 1,2, não RPS: 0,5 ± 0,7, p=0,02) em cavalos com fratura não RPS. Cavalos com fratura não RPS tiveram mais diferenças em comparação com seu grupo controle respectivo do que cavalos com fraturas RPS. Os resultados após o reparo da fratura não foram diferentes entre os grupos. PRINCIPAIS LIMITAÇÕES: Estudo retrospectivo, uma população regional de cavalos de corrida, imagens bidimensionais e viés inerente potencial para localização de fraturas, baixo poder estatístico para análise de retorno ao desempenho. CONCLUSÕES: Cavalos de corrida puro­sangue inglês com fraturas condilares não RPS têm um histórico de exercícios mais extenso do que cavalos com fraturas condilares RPS, sugerindo diferenças na etiopatogenia das fraturas.

Positron emission tomography assessment of metacarpal/metatarsal condylar fractures post surgical repair: Prospective study in 14 racehorses.

OBJECTIVES: To assess 18F-sodium fluoride (18F-NaF) positron emission tomography (PET) findings associated with metacarpal/metatarsal condylar fractures at the time of fracture repair and through healing. STUDY DESIGN: Prospective descriptive study. ANIMALS: Fourteen Thoroughbred racehorses. METHODS: 18F-NaF PET was performed within 4 days of surgical metacarpal/metatarsal condylar fracture repair, on both the injured and contralateral limb. Follow-up PET scans were offered at 3- and 5-months post fracture repair. Areas of abnormal uptake were assessed using a previously validated grading system. RESULTS: Eight fractures were located in the parasagittal groove (PSG) (six lateral and two medial) and six fractures were located abaxial to the PSG (non-PSG) through the palmar/plantar condyle (all lateral). All horses in the latter group had uptake in the lateral palmar condyle of the contralateral limb suggestive of stress remodeling. Three horses with PSG fractures had uptake in a similar location in the contralateral limb. Horses with lateral condylar fracture only presented minimal or mild uptake in the medial condyle, which is considered atypical in the front limbs for horses in full training. Four horses developed periarticular uptake in the postoperative period suggestive of degenerative joint disease, three of these horses had persistent uptake at the fracture site. These four horses did not return to racing successfully. CONCLUSION: The findings of this study provide evidence of pre-existing lesions and specific uptake patterns in racehorses suffering from metacarpal/metatarsal condylar fractures. CLINICAL SIGNIFICANCE: PET has a possible role in the prevention, diagnosis, and postoperative monitoring of metacarpal/metatarsal condylar fractures in racehorses.

Ex vivo biomechanical evaluation of an adhered fiberglass and polymethyl methacrylate sole-hoof wall cast on stabilization of type III distal phalanx fractures under simulated physiologic midstance loads.

OBJECTIVE: To evaluate the effect of the application of a novel fiberglass-glue cast (FGC) on the fracture gap width in experimentally created type III distal phalanx fractures in cadaveric specimens under simulated physiologic loads. STUDY DESIGN: Ex vivo biomechanical laboratory study. ANIMALS: Nine unilateral adult equine cadaver forelimbs. METHODS: Type III distal phalanx fractures were created in forelimb specimens, which maintained distal components of the passive stay apparatus. The fracture gap was measured at 5%, 20%, 25%, 50%, 75%, and 95% of fracture length (palmar articular border to solar margin) using D65Pr-PaDiO radiographs. The limb was axially loaded (700, 3600, 4600, and 6700 N) before, during, and after removal of a woven fiberglass cloth and polymethyl methacrylate cast that encompassed the sole and distal portion of the hoof wall (FGC). Fracture gap widths were compared among loads and treatments using a mixed model ANOVA. RESULTS: On average, under simulated physiological midstance loads, the fracture gap width was 0.2 mm smaller after FGC application, with the greatest decrease (0.5 mm) near the articular surface. On average, it was 0.3 mm smaller than after FGC removal. Fracture gap width was 0.1 mm greater when midstance loads transitioned from standing load to walking, trotting, and gallop loads. The fracture gap width increased by 1.3 mm with increasing distance from the articular surface. CONCLUSION: The FGC reduced the fracture gap width and prevented the fracture gap widening that occurred after FGC removal. CLINICAL SIGNIFICANCE: The findings support consideration of FGC use in the treatment of horses with type III distal phalangeal fractures.

Increasing tourniquet number has no effect on amikacin concentration within the radiocarpal joint in horses undergoing intravenous regional limb perfusion.

OBJECTIVE: To determine whether IV regional limb perfusion (IVRLP) performed in the cephalic vein with a wide rubber tourniquet (WRT) applied proximal and distal to the carpus results in a higher peak concentration (Cmax) of amikacin in the radiocarpal joint (RCJ), compared with the Cmax for IVRLP using a single WRT proximal to the carpus. ANIMALS: 7 healthy adult horses. PROCEDURES: Horses underwent IVRLP using standing sedation with 2 g of amikacin sulfate diluted to 60 mL by use of saline (0.9% NaCl) solution in the cephalic vein with 2 different tourniquet techniques; proximal WRT (P) and proximal and distal WRT (PD). Synovial fluid was collected from the RCJ at 5, 10, 15, 20, 25, and 30 minutes after IVRLP. Tourniquets were removed after the 30-minute sample was collected. Blood samples from the jugular vein were collected at 5, 10, 15, 20, 25, 29, and 31 minutes after IVRLP. Amikacin concentration was quantified by a fluorescence polarization immunoassay. Median peak concentration (Cmax) of amikacin and time to maximum drug concentration (Tmax) within the RCJ were determined. RESULTS: Median peak concentration in the RCJ was 1331.4 µg/mL with technique P and 683.1 µg/mL with technique PD. Median Tmax occurred at 30 minutes with technique P and 25 minutes with technique PD. No significant (Cmax, P = 0.18; Tmax, P = 0.6) difference in amikacin Cmax or Tmax between techniques was detected. CLINICAL RELEVANCE: Placement of 2 WRTs offers no advantage to a single proximal WRT when performing IVRLP to deliver maximal amikacin concentrations to the RCJ using IVRLP.

Catastrophic gastric rupture in a horse secondary to psyllium pharmacobezoars.

A mare was euthanized because of gastric rupture secondary to complete duodenal obstruction by 2 bezoars located in the pylorus and proximal duodenum. Infrared spectroscopy showed that the bezoars were composed of psyllium. The mare had been receiving treatment with a pelleted psyllium product at 4 times the recommended dosage. Veterinarians should be aware that treatment of colic in horses with pelleted psyllium products could be associated with gastric impaction.

Rupture gastrique catastrophique secondaire à des pharmacobézoards de psyllium en boulettes chez un cheval. Une jument a été euthanasiée en raison d'une rupture gastrique secondaire à une obstruction duodénale complète par deux bézoards situés dans le pylore et le duodénum proximal. La spectroscopie infrarouge a montré que les bézoards se composaient de psyllium. La jument avait reçu un traitement composé d'un produit de psyllium en boulettes à quatre fois la dose recommandée. Les vétérinaires devraient être au courant que le traitement des coliques chez les chevaux avec des produits de psyllium en boulettes pourrait être associé à une impaction gastrique.(Traduit par Isabelle Vallières).