Peter Green MRCVS reports on back conformation and saddle fit
SETTING THE PACE
A MUTATION in the gene labelled DMRT3, known as the “gait-keeper gene”, gives horses the ability to pace or tolt, rather than trot. This mutation is found in Icelandic horses (pictured) and other breeds with this ability.
Swedish geneticists studied pedigree Icelandic horses, which are rigorously scored for their conformation and for the quality of these “lateral” gaits. They analysed the DNA of 177 performance-tested horses and discovered a genomic region strongly linked to the conformation of the withers, back and croup.
The scientists found two opposite forms, or haplotypes, of this genetic code. Horses with one haplotype had higher withers, a flatter back and a lower, more muscled croup – creating an “uphill” conformation. Horses with the opposite haplotype had a more level or even a “downhill” conformation.
When the quality of the pace and tolt of the individual Icelandic horses was compared with the genetic type, there was a strong correlation with the genetics. The more favourable haplotype, producing the uphill conformation, was associated with much better pacing and tolting. This means that Icelandic horses can be genetically screened to find out how good their lateral gaits will be.
FIT FOR PURPOSE
SADDLE-FITTING is a skilled job but it is subjective, with some differences of opinion among saddlers.
Electronic pressure mats, sometimes used to identify areas of unacceptable pressure beneath the saddle, have the added advantage of generating data while the horse is worked.
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Swiss scientists compared the results of manual saddle-fitting with pressure mat data in 196 healthy riding horses, with no known history of back problems, and with the saddle currently being used by the riders. All were assessed by an experienced saddle-fitter and then by an under-saddle electronic mat as the horses were ridden. The saddles were English patterns: dressage, showjumping or general purpose (GP).
Only 10% of the horse’s saddles were deemed a “perfect” fit by both saddle-fitter and pressure mat. Almost a third of the horses were found to have painful backs. Problems varied with saddle type: dressage saddles tended to have panels that were too steep on the back of the horse and not symmetrical, the waists of the showjumping saddles were generally too narrow, and the GP models tended to be badly balanced.
There was good correlation between the assessment made by the professional saddle-fitter and by the pressure mat. It was also clear that sheepskin numnahs were better than other pads in spreading pressure, and that there was only poor correlation between the detected back pain and the worst-fitting saddles.
Back pain in horses is complicated. Although correct saddle fit is essential, it is only one part of the problem.
You can also read this feature in the 13 May issue of Horse & Hound magazine.
