Incidence and causes of osteochondrosis in Italian Trotter horses

Correct skeletal development is important especially in athlete horses, since structure abnormalities and problems may lead to pathological conditions and affect race performances. OCD (osteochondrosis dessicans) is a developmental orthopaedic disease that involves a local or generalised failure of endochondral ossification affecting the epiphyseal and/or metaphyseal cartilage. OCD can be a consequence of several events: 1) development of a cartilaginous flap (chip); 2) abnormal differentiation and maturation of cartilage cells; 3) failure of cartilage matrix to calcify and its related thickness; 4) nutritional disorders. Its incidence and economic losses-related to the surgical treatment are attracting increasing interest in Italy. Aim of the research was to assess sex and stallion’s influence on OCD in Italian Trotter foals and on the agonistic careers. The records of 735 foals from different stables born over 8 years from 55 stallions and 215 mares were studied. Foals were subjected to radiological screening (10-16 months old) and surgical removal of bone chips was performed in those affected by OCD. Subjects were divided into 2 classes: A) absence of OCD; B) presence of OCD, regardless of severity and location. For each foal data regarding genealogy, date of birth, sex, age at surgery, utilisation in competitions, races run and competitive career were analysed. Overall, 14.3% of the foals had OCD, in line with the literature. There were significant differences attributable especially to the stallion effect. Four stallions had more offspring with OCD (30-45%) than the mean; 4 more had consistently normal offspring (> 96%). The proportion of foals used in competitions was slightly, but not significantly, greater in Class A than Class B. There were no differences in age at 1st race, and competitive survival curves were substantially similar. In conclusion even if subjects with OCD are not to be considered unsuitable for competitions, it is extremely important to continue OCD monitoring via early evaluation by breeders and veterinarians as well as to focus on nutritional aspects to obtain the best possible growth of foals