Relationships between electrocardiographic findings, racing performance and training in Standardbred horses

SUMMARY The presence of abnormal T waves in three or more electrocardiographic leads has been used to diagnose the cause of poor race performance in horses. This study investigated the relationship between previous racing performance in Standardbred horses and T waves, and the effect of training on the T wave. Thirty-two horses were electrocardiographed in two Sydney racing stables. Sixteen horses (50%) had ECGs with three or more leads with abnormal T waves, and these horses had won more races, had a greater ratio of wins per start and a greater number of dollars earned per start than horses with less than three abnormal T waves (P < 0.05). Horses with abnormal T waves also had significantly faster racing times (P < 0.01). There were significant (P < 0.01) correlations between the number of abnormal T waves and both number of wins (R = 0.47) and dollars earned per start (R = 0.45). Fastest winning mile rate was also negatively correlated with number of leads with abnormal T waves (R =?0.52, P < 0.01). Twenty two horses were also electrocardiographed within seven days of good racing performance. The mean number of abnormal T waves was 2.7 ± 0.41, and the mean T wave amplitude in the four chest leads (CV, CR, CL, CF) was 0.9 ± 0.15 mV. Thirteen horses (59%) had abnormal T waves in three or more leads. The effect of training on the T wave was also investigated in nine previously untrained and unraced Standardbred racehorses. There were significant effects of training (P < 0.01) on the number of abnormal T waves and mean chest lead T wave amplitude. These increases occurred in the second phase of training during which faster exercise, race trials and racing were conducted. We concluded that abnormal T waves are a common finding in the race-fit Standardbred horse, and can be found in more than 50% of horses currently performing well in races. In addition, chest lead T waves become more positive after training.     

Locking compression plate osteosynthesis of sacral fractures in three heifers

Objective: To describe a technique used for reduction and internal fixation of sacral fractures in cattle. Study Design: Case series. Animals: Three heifers aged 19–32 months with deformation of the tail head and tail paralysis attributable to a closed fracture of S5 or S4 and S5. Methods: Fractures were reduced and repaired under general anesthesia. A narrow, 6–10‐hole, locking compression plate (LCP) was placed on the spinous processes of S5 and the first coccygeal (Co1) using 5.0 mm locking head screws. Follow‐up inquiries were made by telephone (3/3), and cows were examined clinically and radiographically 2 (1 cow) to 9 (1cow) months postoperatively. Results: No complications were encountered. The range of movement of the tail improved so that soiling of the tail during defecation was no longer a problem. In all heifers, the normal top line was restored and there was no narrowing of the pelvic canal. Unassisted calving occurred in all heifers, and follow‐up radiographs for 2 cows showed complete fracture healing. Conclusion: LCP‐osteosynthesis of the spinous processes provided sufficient stability for internal fixation of sacral fractures. Marked improvement in tail function occurred postoperatively without decompression by laminectomy.     

Traumatic atlanto-occipital dislocation in a calf

In a 7-week-old calf neurologic symptoms occurred after an accident in the feeding grid. The calf was alert but in left lateral recumbency. After having been placed on its right side it showed a sideward drift to the left. Following head movement, an asynchronous movement of the eyes could be observed. Lesions of the upper motor neuron system, N. vestibulocochlearis, Nn. oculomotorius, trochlearis and/or abducens as well as N. vagus were suspected. Radiological examination of the occipital region and cervical spine revealed an atlanto-occipital subluxation of the atlas. Based on all these findings, the diagnosis of traumatic atlanto-occipital dislocation was made and the calf was euthanized. The pathological findings confirmed this diagnosis.     

Haemorrhage caused by thrombocytopenia in 3 calves

The clinical findings and treatment of 3 calves with bleeding attributable to severe thrombocytopenia (1000 to 5000 platelets/microl) are described. The calves responded to treatment with whole blood transfusion, dexamethasone and other drugs. One calf was subsequently diagnosed with persistent bovine viral diarrhoea virus infection and was euthanased despite a favourable response to treatment. The other two calves were discharged after platelet counts had normalised and bleeding had stopped.