A research project carried out at the Norwegian School of Veterinary Science has revealed that 50.7% of Norwegian Standardbred yearlings suffer from loose bone fragments and lesions in their joints.
Genetics links in horse joint diseases
Developmental orthopedic disease which appears in many forms is well recognized in the horse, and can result in lameness or poor performance.
Developmental orthopedic disease is well recognized in the horse, and can result in lameness or poor performance. It can appear in various forms such as: osteochondrosis (OC), /osteochondrosis dissecans (OCD), palmar/plantar osteochondral fragments (POF), ununited palmar/plantar eminences (UPE,) and dorsoproximal first phalanx fragments.
The aim of the study, led by Sigrid Lykkjen, was to assess the prevalence, development and interrelation of the various forms of developmental orthopedic disease (DOD) affecting the tarsocrural, metacarpophalangeal (MCP) and metatarsophalangeal (MTP) joints in Standardbred trotters.
The work formed the basis of her PhD thesis entitled “Genetic studies of developmental orthopedic joint diseases in the Standardbred trotter”.
The research was carried out as a collaborative project between the Horse Clinic and Department of Disease Genetics at The Norwegian School of Veterinary Science, the University of Ås and the University of Minnesota.
Tarsocrural and MCP/MTP joints of 464 Norwegian Standardbred yearlings, were examined radiographically. Lykkjen assessed the prevalence of osteochondral lesions and also looked at the interrelation between affected sites.
Lykkjen found osteochondral lesions in 50.7% of the horses. OC/OCD of the tarsocrural (hock) joint occurred in 19.3%. Of the lesions in the hock joint, OCD of the distal intermediate ridge of the tibia (DIT) was the most common. The prevalence of OC/OCD in MCP joints was 3.6%, whereas the prevalence of POF and UPE in MCP/MTP joints was 23.1% and 3.9%, respectively.
It was common for horses to have similar lesions on the opposite leg. There was an association between OCD of the distal intermediate ridge and OCD of the lateral trochlea ridge, and between POF and UPE.
The research project also included analyses of the horse’s whole genome to try to identify variations in DNA that could be linked with the occurrence of osteochondrosis and Birkeland fractures.
Lykkjen found areas of DNA associated with these two diseases in several chromosomes, showing that these are complicated ailments influenced by many genes.
The high prevalence results for tarsocrural OC/OCD ,which were, in fact, higher than in a previous study of Swedish Standardbreds, emphasise the need for breeders to take account of these diseases in planning their breeding programs.