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'Bad attitude' may be due to hock pain,
Horse Trust research shows
A 'bad attitude' to exercise may in fact be due to hock pain caused by undiagnosed and untreated
osteoarthritis, research funded by The Horse Trust has revealed.
Osteoarthritis of the lower hock joints - better known as bone spavin - is the most common cause
of hind limb lameness in horses.The final phase of degenerative joint disease (DJD), in the lower
three hock joints,its effect ranges from mild to severe and incapacitating. Although X-rays can help
with diagnosis, subtle lesions can be difficult to detect. Ultimately, the horse may have to be put
down if the condition cannot be cured.
The extent of this disease in the equine population prompted The Horse Trust to fund a study to
improve understanding of hock pain through investigation of the bone and joint unit, undertaken
by Rachel Murray, Sue Dyson and Tony Blunden of The Animal Health Trust, Newmarket, and Allen
Goodship of the Royal Veterinary College and University College London.
The study compared hock joints from horses with a known history of pasture rest, low-intensity
ridden exercise and high level competition training including showjumping, dressage and
three-day eventing. The joints all came from animals which had been humanely destroyed for
reasons other than incurable osteoarthritis and included joints from animals which had pain
confirmed by radiography and from horses that exhibited pain but in which no radiographic changes
had been identified.
X-ray, magnetic resonance imagery (MRI), bone densitometry and detailed microscopic examination
determined each joint's structure of bone, cartilage and ligaments, and the findings were compared
to evaluate the best way of detecting painful abnormalities in the lower hock.
The study found that horses exhibiting lameness due to bone spavin had marked abnormalities of
the bone thickness pattern found in normal hock joints, including change in the cartilage, bone,
ligaments or a combination of these. It also appeared that working in straight lines has different
effects from circles and turns, suggesting that altering the type of work a horse does could modify
the strains experienced by different sites in the joints and potentially be used in prevention,
rehabilitation or management of osteoarthritic changes.
MRI provided a clearer identification of subtle abnormalities, making it easier to diagnose bone spavin.
The researchers claim their study has provided a greater understanding of what is normal and abnormal
in the horse's hock structure, and provided the first description of pathology in painful hocks
without radiographic evidence of disease. It has also shown the great potential for use of MRI
in diagnosis, management and study of this disease. We believe that the results of this study have
improved welfare by improving understanding of how the disease develops and improving diagnosis of
disease using MRI.
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