The type and location of deep digital flexor tendon (DDFT) lesions may be important in predicting outcome. The objectives of this study were to determine the frequency of different types of DDFT lesions within the hoof capsule and to determine whether lesion type predicts return to athletic activity. Lesions of the DDFT were divided into: core lesions, dorsal border lesions and parasagittal splits. Lesion location was documented, and follow‐up information was obtained by telephone survey at least 18 months after diagnosis. Of 168 horses with primary DDFT injury, 54 horses had dorsal border lesions, 59 had parasagittal splits and 55 had core lesions. Twenty‐five per cent of all horses returned to previous levels of athletic activity within 18 months of MRI evaluation. Horses with complete splits or core lesions of the DDFT were significantly less likely to return to some level of athletic activity than horses with dorsal border lesions P<0.001. Dorsal border lesions of the DDFT appear to have a better prognosis than core lesions or parasagittal splits. This study provides additional information that may help clinicians predict the prognosis for different types of DDFT injury.

Neutrophilic airway inflammation is highly prevalent in racehorses in training, with the term mild to moderate equine asthma (MMEA) being applied to the majority of such cases. Our proposed study is largely derived from the strong association between MMEA in racehorses and their entry into a race training program. The objectives of this study are to characterise the effect of training on the local pulmonary immune system by defining the gene and protein expression of tracheal wash (TW) derived samples from Thoroughbred racehorses prior to and following commencement of race training. Multiomics analysis detected 2138 differentially expressed genes and 260 proteins during the training period. Gene and protein sets were enriched for biological processes related to acute phase response, oxidative stress, haemopoietic processes, as well as to immune response and inflammation. This study demonstrated TW samples to represent a rich source of airway cells, protein and RNA to study airway immunity in the horse and highlighted the benefits of a multiomics methodological approach to studying the dynamics of equine airway immunity. Findings likely reflect the known associations between race-training and both airway inflammation and bleeding, offering further insight into the potential mechanisms which underpin training associated airway inflammation.

Background: Vitamin D deficiency is common in humans and is increasingly linked to the pathogenesis of a multitude of diseases including obesity and metabolic syndrome. The biology of vitamin D in horses is poorly described; the relative contribution of the diet and skin synthesis to circulating concentrations is unclear and associations with the endocrine disease have not been explored.Objectives: To determine the relationship between management, season and endocrine disease and vitamin D status in horses.Study design: Cross‐sectional cohort study.Methods: Plasma concentrations of 25‐hydroxyvitamin D₂ (25(OH)D₂) and D₃ (25(OH)D₃) were measured by liquid chromatography‐tandem mass spectrometry in 34 healthy unsupplemented grazing ponies and 22 stabled Thoroughbreds receiving supplementary vitamin D₃ in feed. A nested group of 18 grazing ponies were sampled on long and short days (>12 and <12 h of light/day) to determine the effect of sunlight exposure. In addition, the relationships between age, sex, adiposity, serum insulin, adrenocorticotropic hormone and vitamin D status were assessed in a mixed group of 107 horses using a linear regression model.Results: All animals had a measurable level of 25(OH)D₂ (median 10.7 nmol/L) whilst 25(OH)D₃ was only detected in Thoroughbreds receiving D₃ supplementation. Thoroughbreds had lower concentrations of 25(OH)D₂ than ponies (7.4 vs. 12.6 nmol/L, p < 0.01). In grazing ponies, 25(OH)D₂ concentrations were significantly higher on long days compared to short days (14.4 vs. 8.7 nmol/L, p < 0.01), whilst 25(OH)D₃ was undetectable. Measures of increased adiposity, but not basal insulin, were associated with higher 25(OH)D₂ concentrations, conversely to humans. Increasing ACTH was associated with lower 25(OH)D₂ (p < 0.01).Main limitations: Vitamin D₂ concentrations were not measured in grass or forage.Conclusions: In horses 25(OH)D₂ is the predominant vitamin D metabolite, and there is an apparent lack of endogenous vitamin D₃ production. The relationship between vitamin D and endocrine disorders in horses does not reflect that of other species and warrants further investigation.

Solar foot penetration is one of the causes of deep digital flexor tendon injuries in horses, however, limited information is available on the prognosis for return to soundness in the absence of synovial sepsis. Objectives of this retrospective observational study were to describe low‐field magnetic resonance imaging (MRI) findings and long‐term outcome for a group of horses with this combination of clinical problems. Horses were included if low‐field standing MRI of the foot was performed following puncture wounds, injury of the deep digital flexor tendon was diagnosed, and sepsis was confirmed to be absent in all adjacent synovial structures (distal interphalangeal joint, navicular bursa, and digital flexor tendon sheath). Medical records were reviewed and MRI studies were re‐interpreted. Follow‐up information was obtained via a telephone questionnaire at a minimum of 6 months post‐injury. A total of 11 horses met inclusion criteria. In three horses, the deep digital flexor tendon injury was only visible in the T2 fast spin echo sequence and contrast radiography improved diagnostic certainty. The most commonly affected area was between the distal border of the distal sesamoid bone and the facies flexoria of the distal phalanx (6/11, 55%). Six horses (60%) had an excellent outcome (5, show jumping; 1, general purpose) and returned to full athletic function. Five horses (40%) were sound but had not yet resumed full work at the time of follow‐up. Findings indicated that the prognosis for return to soundness can be good for horses with solar penetration, deep digital flexor injury, and absence of synovial sepsis.