Effect of Laryngeal Hemiplegia of Thoroughbred Racehorses on Racing Performance and the Usefulness of Laryngoplasty Performed on Horses with Laryngeal Hemiplegia

Abstract

We evaluated the effect of laryngeal hemiplegia (LH) on racing performance in thoroughbred racehorses as well as the effects of laryngoplasty on racing performance. A total of 294 racehorses (LH group) were diagnosed with LH were analyzed for this study. A total of 294 racehorses (no-LH group) not suffering from LH extracted at random from the Japan Racing Association population were used for comparison of sex and body weight. The epidemiological investigation evaluated relationships between the occurrence of LH and sex, body weight, the number of the horses that were late for the time limit, the rate of the horse that returned to racing after diagnosis, the number of races run, and race results. Evaluations of the effect of laryngoplasty on racing performance were performed on the rate of the horse that returned to racing after laryngoplasty or no-laryngoplasty, the number of races run, and race results. The ration of males or geldings to female in the LH group was higher than it of the no-LH group. Body weight of the LH group was significantly heavy as compared with it of the no-LH group. It became clear that there is a tendency to suffer the male with heavy weight from LH compared with female. In Grade III, the racing performance was significantly lower than Grade I and Grade II. The racing performance of the laryngoplasty group was higher than the no-laryngoplasty group. It became clear that the horses that have severe LH were poor performance, and laryngoplasty was the useful surgical technique for LH treatment.