Half of a group of Norwegian standardbred horses of the same age suffered from loose bone fragments and defects in their joints, research reveals.
The doctoral research project carried out at the Norwegian School of Veterinary Science revealed that 50.7 per cent of the horses studied had such problems.
Sigrid Lykkjen, a doctor of veterinary medicine, took x-rays of 464 year-old standardbred trotters born in 2006 and 2007 and discovered that 21.5 per cent of them had osteochondrosis in the hock and 23.1 per cent suffered from Birkeland fractures of the fetlock.
Osteochondrosis is a term used to describe a group of disorders that affect the growing skeleton. Birkeland fractures involve chip or avulsion-type fractures of the palmar or plantar proximal aspect of the first phalanx.
Osteochondrosis, Birkeland fractures and other loose fragments in joints are frequently occurring orthopaedic diseases in horses. They can result in lameness and weaker performance.
The occurrence of osteochondrosis found in Lykkjen’s work was significantly higher than that previously reported in Norwegian and Swedish studies.
X-ray findings from an earlier Norwegian study of 753 standardbred trotters and pedigree information were included in the study when calculating the genetic parameters of these two diseases.
Genetic analyses show that osteochondrosis occurring in the hock and Birkeland fractures in the fetlock are caused by complex, hereditary diseases, which must be taken into account in breeding.
Lykkjen’s research demonstrates that osteochondrosis of the hock and Birkeland fractures are hereditary diseases and a positive genetic correlation indicates that these disorders may share the same genes.
Calculations show that the occurrence of these diseases is equally high in American and French trotters.
The research project also includes analyses of the horse’s whole genome for the purpose of uncovering DNA variations that may be linked with the occurrence of osteochondrosis and Birkeland fractures.
Lykkjen found areas of DNA associated with these two diseases in several chromosomes, which proves that these are complicated ailments influenced by many genes.
Taken as a whole, the results of the research confirm that osteochondrosis of the hock and Birkeland fractures of the fetlock in standardbred trotters are worthy of further research.
Breeders should take account of these diseases in their decision-making, she said.
Lykkjen’s thesis is entitled “Genetic studies of developmental orthopaedic joint diseases in the standard bred trotter”.
Her doctoral 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.
Lykkjen attained her veterinary degree at The Norwegian School of Veterinary Science in 1996.
She worked for three years at a private veterinary clinic before being employed by the school in 1999. There, she completed an internship at the Horse Clinic and qualified in 2007 as a Norwegian specialist in equine diseases.
She began her doctoral research in 2008.
Lykkjen currently holds a post as a university lecturer at the Horse Clinic.