Quantification of the prevalence of angular and flexural limb deformities in a population of Standardbred and Thoroughbred foals in New Zealand

Abstract

Abstract Aim: To quantify the prevalence of angular and flexural limb deformities in a population of Standardbred and Thoroughbred foals in New Zealand in their first week after birth and to describe the influence of several risk factors on the prevalence of these deformities. Methods: Data were collected at two Standardbred stud farms and two Thoroughbred stud farms located in the Canterbury (n=1) and Waikato (n=3) districts. Angular and flexural limb deformity data of the 2010 foal crop were collected from the first week after birth to 15 months of age. Foals were scored at three different visits in their first year. At visit 1 general foal information was recorded consisting of: name of the sire and dam, horse name, foal number or parity, last day of service, date of birth, gender of the foal and the name of the stud farm. Other foal information was recorded at every visit such as visit number and date, name of the recorder, the conformation and size of the foal and the condition score. Limb deformity information was also recorded at every visit as well as severity of the deformity. All the recordings mentioned above were made on a proforma limb deformity sheet for every individual foal. Results: Of the 345 foals included in the study only 313 foals had complete limb deformity information. 253/313 foals had at least one problem recorded during their first visit and 196/253 had more than one problem recorded at the same visit. Outward from the knee was the deformity most often recorded (162/313; 52%). Fourteen percent (44/313) of the foals were recorded to have contracted tendons on either the front or hind legs and 10.5% (33/313) were recorded to be windswept. Foals with a higher condition score and born mid season were respectively 0.26 times less likely and 7.20 times more likely to be windswept compared to their reference group. Thoroughbred foals were 0.35 times less likely to have contracted tendons on the front legs than Standardbred foals. Larger foals and foals born mid season were 2.80 and 3.28 times more likely to have contracted tendons on the front legs compared to medium foals and foals born early in the season respectively. Finally, Thoroughbred foals were 0.21 times less likely to be inward from the knee than Standardbred foals and fillies were 2.74 times more likely to have this deformity compared to colts. Conclusion and clinical relevance: The prevalence found in this study for some of the limb deformities varies from the prevalence found in studies performed in other countries. Associations were found between 5/7 risk factors and 3/11 limb deformities. This study provides preliminary work where future studies could build on and it could provide a reference point for the New Zealand industry. Furthermore it could give an opportunity to examine if angular and flexural deformities are associated with racing and sale performances.