On-farm pregnancy rates in both breeds were higher than previously reported and likely reflect improvements in reproductive management. The disparity between breeds in the inseminations per cycle and proportion of barren mares exposed the differing structures of the two industries, and presents a target for improving the reproductive efficiency in STBs. The difference between breeds in the multiple pregnancy rate per cycle likely reflects the higher ovulation rate of TB mares. The variability in pregnancy rate per cycle between the 22 stallions was associated with differences in individual inherent fertility and the quality of stallion management.

Background: Atrial fibrillation (AF) impacts performance and horse and jockey safety. Understanding the outcomes of AF identified postrace will better inform regulatory policy. Hypothesis/Objectives: To investigate the outcomes after episodes of AF identified postrace and determine whether affected horses are at increased risk of additional episodes compared to the general racing population. Animals: Total of 4684 Thoroughbred racehorses. Methods: Race records for Thoroughbred horses racing in Hong Kong from 2007 to 2017 were reviewed. Horses that performed below expectation were examined by cardiac auscultation and ECG. Incidence and recurrence of AF were compared between horses with and without a history of AF and between horses with paroxysmal and persistent episodes using Fisher's exact test. Results: There were 96 135 race starts during the study. Atrial fibrillation was identified in 4.9% of horses, with an overall incidence of 2.7 episodes per 1000 starts. The incidence of AF in horses after any previous episode (12.8 per 1000 starts) was higher than for horses with no previous episode (2.4 per 1000 starts; odds ratio [OR], 5.3; 95% confidence interval [CI], 3.8-7.6). Recurrence was seen in 64% of horses previously treated for persistent AF, which was higher than recurrence in horses with paroxysmal AF (23%; OR, 5.9; 95% CI, 1.6-21.2). Median duration between episodes was 343 days (range, 34-1065). Conclusions and Clinical Importance: Thoroughbreds are at increased risk of recurrent AF after both paroxysmal and persistent episodes, but the duration of time between episodes varies widely. These findings support a substantial burden of AF among individual Thoroughbred racehorses.

cTnI is elevated in horses with myocardial disease and elevated to a lesser degree in some horses with structural heart disease or lone arrhythmias. The association between cTnI concentration and survival was not clear.

SummaryA Thoroughbred gelding had chronic episodic intra-abdominal haemorrhage following standing castration, presumed to originate from a testicular artery. No coagulopathy could be detected and resolution of haemorrhage was achieved by laparoscopic electrocoagulation of both testicular arteries 6 weeks after castration. Blood drained from the abdomen during surgery was filtered then auto-transfused. Post operative complications included pigmenturia, incisional pain and large colon impaction.

Evidence of myocardial injury was observed in horses with acute abdominal disease, and this injury was associated with severity of illness. Recognition of myocardial injury could improve treatment of acute abdominal disease in horses.