Osteochondrosis; a literary review and a retrospective study of OCD prevalence in Norvegian and Hungarian horses

Abstract

Osteochondrosis and osteochondritis dissecans is a highly debilitating disease, especially in the equine sport industry. The disorder is defined as a focal disturbance in the endochondral ossification process, and multiple etiological factors have been suggested in the background. Many of the older ideas have today been discarded due to lack of evidence, and the focus is now highly directed toward the failure of vascular canals as well as genetic markers for OC and OCD. Two main countries are at the front of these studies, Norway mainly focusing on the failure of vascular canals as a possible major etiological factor, and Germany with its well documented genetic research in both warmblood and coldblood breeds. In this thesis a total of 129 horses, 50 from Hungary and 79 from Norway, was reviewed. The data was collected from 2007-2009 in Norway and from 2009-2010 in Hungary. All horses diagnosed with OCD were included, with the exception of palmar/plantar fragments of P1. As a general tendency the results showed that Hungarian horses were much older by the time the lesions were diagnosed and treated, and the average age was much higher than what was seen in the Norwegian data. There was also a higher occurrence of geldings in the Hungarian data, while there was a high occurrence of stallions in the Norwegian data. It was not possible to compare the incident of breeds affected since there is an obvious difference in breeds in the two countries. For the feature it would be advisable to get the terminology of this disease under some sort of internationally approved classification system. This would make it much easier to compare results when publishing new material. Today there are too many important details which are not agreed upon, which makes it very hard to compare incidents, heritability etc, which are important data to determine the aetiology and pathogenesis of this disease. The fact that incident rapports includes everything from 7-60% is not necessarily due to the group examined, rather that the different authors have different evaluation of OCD and includes different amounts of predilection sites. Perhaps a study across land borders, focusing mainly on the different breeds, to get a proper proportion of incident and heritability would be a project for new research. It would also be interesting to look at how many race horses are operated each year, without clinical symptoms of the disease, and how does this affect them in their further life as performing athletes? Does is affect them at all, is it negative consequences or is it highly likely they would develop signs later, and then need an operation anyway? All these questions would be helpful to map the disease further.