Cerebellar Abiotrophy in Arabian Horses

30 Jan. 2010 by Lisa Goodwin-Campiglio.

If a Part-Bred Arabian has Carriers on both sides of its pedigree from the original Arabian blood introduced, it will and can be affected. If it has an Arabian Carrier in its background and the mutated allele has passed forward, it can be a Carrier. CA (Cerebellar Abiotrophy) is found in Arabian bloodlines primarily. It also has been found in the Gotland pony whose original ancestor was a Syrian imported Arabian crossed on a local mare. CA has also been found in Miniature Horses and the Eriskay pony. These breeds also have had infusions of purebred Arabian blood, all be it some many generations ago. In attempts to purify the breeds and establish them as specific breeds out of a limited gene pool , much inbreeding has occurred...thus bring the defective gene forward. Because the defective gene can do this, is why it is so terribly important for a Carrier (much less an affected) SHOULD NOT BE USED to cross with other breeds. It could pass forward its defective gene, respectively get ´lost´ in the mix of different breed genes and reappear generations later, long after the original purebred Arabian Carrier has been forgotten.

CA has not been appearing in the purebred Thoroughbred lines, probably because this breed is raised for its high performance qualities and usually thoroughly tested under saddle. Horses which do not make it or can not be put under saddle are usually culled in one way or another.  If CA was ever in the thoroughbred bloodlines, it has most probably been bred out. They have been very strict in their breeding for generations to keep within their recognized mare families.

The Anglo-Arab societies are especially aware of CA in Arabians and as they require a specific percentage of both Arabian and Thoroughbred blood in order to be register able, they are requiring any new infusions of Arabian blood to be tested prior to being introduced.

Frankly in my own opinion, a tested part bred Affected or Carrier will tell the researcher much more about the origin of the CA defective allele as it will only come from the infusions of the Arabian(s) used in the background and in some cases this "Arabian" is way back in the pedigree and there is only one Arabian cross. This is how some of the early purebred Arabian carriers have been identified and documented long before testing was developed.