Cerebellar Abiotrophy in Arabian Horses

20 Feb 2010, Scottsdale, AZ:
"Genetic Disorders: From Knowledge to Action"
A Free Symposium for Arabian Breeders and Owners

WHEN: Saturday, February 20, 2010, 8:00 a.m. — 11:00 a.m.
WHERE: Brett’s Barn, West World Show Grounds, Scottsdale, Arizona.
PANEL: Dr. Cecilia Penedo, Veterinary Genetics Laboratory, University of California at Davis, director of research that identified genetic markers for Cerebellar Abiotrophy (CA) and developed the marker-based test.
Beth Minnich, Chair, Genetic Diseases Task Force, Arabian Horse Association.
Paul Husband, Attorney at Law, Fellow of the American College of Equine Attorneys continues at the forefront of educational programming for Arabian breeders and owners

Commentary written by attending breeder Dick Reed of Toskhara Arabians, Aubrey, Texas 76227.

On Saturday morning The Institute for the Desert Arabian Horse, the Arabian Horse Foundation, the Pyramid Foundation and the Arabian Horse Association of Arizonia sponsored a presention on "Genetic Disorders: From Knowledge to Action" at Bretts Barn which is an events building on the show grounds. It started at 8:30 with juices, cereals, rolls and coffee available from 8:00.

 Anita Enander from the Institute for the Arabian Horse introduced the speakers.

There was an audience of about 50 people. I found this disappointingly small because the event was well promoted and important.

Beth Minnich, the Chair of the AHA Task Force on Genetic Diseases, presented information on the genetic diseases which are identified specifically with the Arabian horse. These include SCID (Severe Combined Immunodeficiency), CA (Cerebellar Abiotrophy), GPT (Guteral Pouch Tympany) and LFS (Lavendar Foal Syndrom) amongst others.

She pointed out that the Arabian breed is no more prone to genetic defects than any other breed of horse, or animals in general. As breeders we need to be aware of those we have and develop an understanding of the diseases and learn to prevent the manifistation of the defects in our animals.

The best way to do that is to have a genetic test for carrier status and to use that test to make sure that carrier animals are not bred indiscriminately and that carriers are never bred to carriers. A SCID test has been available for about 10 years, a CA test has been made available in the last year and an LFS test is under development and will be available shortly.

 

The heart of the program was to present and discuss the newly developed test for CA.

The presenter was Dr. Cecilia Torres-Penedo, PHD in Genetics at the Veterinary Genetics Laboratory at UC Davis. She and her group have developed the genetic markers test for CA.
What was new and important information for me was the fact that not all affected animals (that is animals who are homozygous for the defective gene) don't have the same levels of expression of the disease. Some are very seriously affected and cannot survive as foals, other are moderately affected and can survive with special care, and some are lightly or non affected and may lead normal lives. The Arabian horse population from sampling so far appears to have 15-20% as carrier animals.

DIAGRAM presented by Dr. Penedo:
Total tested by UC Davis:1982 (as of 20 Feb 2010)
N/N Clear: 1548 horses (~ 78%)
N/CA Carrier: 397 horses (~ 20%)
CA/CA Affected: 36* horses (~ 2%)
* Includes 2 Danish Sports Horses with Arabian Ancestry.

More work needs to be done on why the level of expression is different and Dr. Torres-Penedo is interested in finding animals who are lightly or non affected but are homozygous for the CA defect so that more complete neuralogical studies can be conducted.

Paul Husband JD specializes in equine law and talked about the legal issues surrounding the disclosure of genetic defects.

The AHA has passed resolutions which require the disclosure of SCID and CA when one knows that a breeding animal is a carrier animal. This is under the ethical practices provisions of the association. He pointed out that these rules don't have the force of law but may be influential in a court of law.

If asked about the carrier status of a horse the owner/seller is required by law to answer honestly. Paul Husband won a large law suit for Tom Selleck when a seller did not dislose drug treatments which had been used to disguise lameness in a horse. Paul said ask questions of a horse seller and get in writing if you want to prevent being duped.

In regard to Arabian horses, Paul Husband was the long time associate and promoter of Khemosabi, the famous stallion was bred by his parents Dr Burt and Mrs Ruth Husband.