An x-ray study of horses’ hooves has shown a gradual reduction in the amount of tissue beneath the coffin bone as animals age.
The Californian researchers based their findings on analysis of 544 x-rays of both front feet of horses of various breeds showing the distal phalanx, also known as the coffin bone. They also analyzed 278 x-rays of the front feet of quarter horses.
The research, at California Polytechnic State University, focused on the curved surface of the underside of the coffin bone, which they termed the Palmar Curve, and the area under the cure, measured as a percentage of hoof material, which they termed the Palmar Metric.
They found that the area under the curve decreased at a rate of 0.28 percent a year for the horses of various breeds, and 0.33 percent a year for the quarter horses.
Matthew Burd and his colleagues, whose findings were published in the August issue of the Open Veterinary Journal, said veterinarians should be aware of age-related change in the concave sole area of the coffin bone.
The researchers said x-rays were the backbone of veterinary evaluations of the equine digit.
They set about to describe a quantitative measurement of the concave, parietal solar surface of the coffin bone – their Palmar Metric – and to demonstrate the manner in which it changes with age.
They used high quality foot x-rays to develop the metric, defining it as the area from a line traced along the curved underside of the coffin bone to the proximal palmar articular surface.
They said that because the Palmar Metric was a ratio, it was not dependent on size of the distal phalanx and could be assessed independent of breed-related differences in foot size.
In humans, age-related, gradual demineralization of bones and a change in bone shape was a well-studied phenomenon.
“To our knowledge, this has not been reported for the distal phalanx of the horse,” they said
They surmised that gradual demineralization of the coffin bone, decreased the concave curve of its underside over time.
They said the Palmar Metric was generally not significantly different between the right or left foot in individual horses.
Differences in the Palmar Metric between the left and right forelimbs may provide insights into the pre-existence, severity, and chronic nature of disease.
“It is hoped that a better understanding of this change throughout the lifetime of the horse, quantified by the Palmar Metric, will yield improvement in hoof care and treatment of foot related disease,” they concluded.
Burd, M.A., Craig, J.J. and Craig, M.F. 2014. The palmar metric: A novel radiographic assessment of the equine distal phalanx. Open Vet. J. 4(2), 78-81.
The full study can read here.