Abstract: REASONS FOR PERFORMING STUDY: The relationship of conformation to future potential injury is a standard approach in practise but, at present, is largely based on subjective observations. OBJECTIVE: To measure conformation in 3-year-old Thoroughbreds and objectively test its relationship with the occurrence of musculoskeletal problems. METHODS: Conformation measurements were taken from photographs using specific reference points marked on the horses and processed on the computer. Clinical observations were recorded for each horse on a regular basis. Stepwise (forward) logistic regression analysis was performed to investigate the relationship between the binary response of the clinical outcomes probability and the conformation variables by the method of maximum likelihood. RESULTS: Clinical outcomes significantly (P<0.05) associated with conformational variables included effusion of the front fetlock, effusion of the right carpus, effusion of the carpus, effusion of the hind fetlock, fracture of the left or right carpus, right front fetlock problem and hind fetlock problem. CONCLUSIONS: Offset knees (offset ratio) contributed to fetlock problems. Long pasterns increased the odds of a fracture in the front limb. An increase in the carpal angle as viewed from the front (carpal valgus) may serve as a protective mechanism, as the odds for a carpal fracture and carpal effusion decreased with an increase in the carpal angle. POTENTIAL RELEVANCE: This study demonstrates relationships between conformation and musculoskeletal disease in the racehorse. The information may be useful in selection and management of the racing Thoroughbred.

Abstract: A traumatic fracture of C2 was diagnosed radiographically in a 1-year-old German Warm-blood stallion. Fracture configuration was difficult to see on survey radiographs. Computed tomography yielded a more accurate assessment of the fracture and facilitated fracture repair with cortical lag screws. Precise screw placement, to avoid spinal cord damage, was obtained by use of computed tomography. Follow-up radiography revealed normal bone healing, and the horse was in dressage schooling 24 months after surgery.

Abstract: Injuries to the superficial digital flexor tendon are common in horses required to gallop and jump at speed. Partial rupture of this tendon usually occurs in the central core of the midmetacarpal region and may be preceded by localised degenerative changes. Post mortem examination of apparently normal equine flexor tendons has revealed an abnormal macroscopic appearance in the central core, characterised by a reddish discolouration. We have previously shown that there is also physical damage to the collagen fibres. In the present study we tested the hypothesis that the abnormal appearance is accompanied by changes in the composition of the extracellular matrix of the tendon. Biochemical analysis of the extracellular matrix demonstrated an increase in total sulphated glycosaminoglycan content, increase in the proportion of type III collagen and decrease in collagen linked fluorescence in the central core of 'degenerated' tendons relative to tissue from the peripheral region of the same tendon. Dry matter content and total collagen content were not significantly different between tendon zones or normal and 'degenerated' tendons. These changes suggest a change in cell metabolism and matrix turnover in the central core of the tendon and are likely to contribute to a decrease in mechanical properties in this part of the tendon, predisposing to the characteristic partial rupture of the tendon.

Abstract: Domestic horses are faced with social challenges throughout their lives due to limitations in social contact, space restrictions and frequent changes in social companionship. This is in contrast to natural conditions where horses live in relatively stable harem bands. Currently, little is known about how repeated regrouping affect horse behaviour and welfare, and it is unknown whether horses may adapt to regrouping. In this study, we aimed to investigate the effects of an unstable group structure, caused by weekly regroupings, on behaviour and frequency of injuries in young horses. Forty-five horses were included in the study and were randomly assigned to the treatments; Stable (S; seven groups of three horses) or Unstable (U; eight groups of three horses). The experimental period lasted 7 weeks, during which horses in Stable groups remained in the same group, whereas one horse was exchanged between Unstable groups every week. The groups were kept in 80m×80m grass-covered enclosures and were fed additional roughage on the ground daily. Social interactions were recorded in Unstable groups immediately after each regrouping (30min), and in both Stable and Unstable groups on day 1, 3 and 6 after each regrouping (2×20min/group/day). Injuries were scored by the end of the experimental period. The level of aggression shown by horses in Unstable groups immediately after regrouping was not affected by week (F5,35=0.42, P=0.83), indicating that horses neither habituated, nor sensitized, to repeated regrouping. Compared to horses in Stable groups, more agonistic behaviour was shown by horses in Unstable groups (i.e. non-contact agonistic; F1,65=5.60, P=0.02), whereas there was no treatment effect on other variables. The level of play behaviour appeared, however, to be more variable in Unstable groups. There was a significant effect of week on the level of contact agonistic interactions as well as greeting behaviour, due to a high occurrence in weeks 4-6. Non-contact agonistic interactions constituted the major part of agonistic interactions (66%). Possibly as consequence, no serious injuries were registered and there was no treatment effect (U=184; P=0.11). We conclude that the behaviour of young horses is affected by group management, and that horses appear not to adapt to weekly regroupings.

Abstract: OBJECTIVE: To describe clinical findings, ultrasonographic features and outcome of injury to the branches of insertion of the superficial digital flexor (SDF) tendon in horses. DESIGN: Retrospective study of 14 cases. PROCEDURE: Fourteen Thoroughbred horses with tendonitis affecting the branches of insertion of the SDF tendon were examined for lameness, location and amount of swelling, and the presence of other musculoskeletal abnormalities. The flexor tendons were assessed by ultrasonographic examination, and recommendations were made for management of the cases. Outcome was assessed by re-examination of some horses, direct communication with the owner or trainer, and examination of race records. RESULTS: The lateral SDF branch was affected in 10 horses; the medial branch in three, and both branches in one horse. Two horses had concurrent injuries to the SDF tendon in the metacarpal region of the contralateral limb. Ultrasonographic findings included swelling of the affected SDF branch, peritendinous fluid accumulation, disruption of normal fibre alignment on sagittal scan, and variable loss of echogenicity. As healing occurred, there was return of normal echogenicity, but normal fibre alignment did not return completely and apparent adhesions formed between the affected SDF branch and adjacent structures. Seven of 10 horses which returned to their previous use were able to compete without further tendon injury. Recurrence of injury occurred in one case, and another two horses developed tendonitis in the metacarpal region. One horse was retired from racing but was able to compete at dressage without recurrence of injury. Two horses were retired for breeding without returning to training, and one horse was sold and lost to follow up but did not race. CONCLUSION: The prognosis is fair for return to previous use following injury to the branches of insertion of the SDF tendon in athletic horses.