Many Thanks for that Great post from the UC Davis CA site!
Geneticists at the Universities of Cornell, Michigan, Iowa and UC Davis in the USA and the Universities of Bern and Zurich in Swizerland, of Gent in Belgium and of Cordoba in Spain have been researching the CA problem since the early 60s.
Similar studies are being explored in Australia as well under the auspices of Professors Dr. J D Baird and Dr. C D Mackensie.
Another in depth description of Cerebellar Abiotrophy is available at Wikipedia:
From Wikipedia, the free encyclopedia
Cerebellar abiotrophy (CA) also referred to as cereballar cortical abiotrophy (CCA) is a genetic neurological disease in animals best known to affect certain breeds of horses and dogs. It develops when neurons known as Purkinje cells in the cerebellum of the brain begin die off. These cells affect balance and coordination. They have a critical role to play in the brain. The Purkinje layer allows communication between the cortical layers in the cerebellum. Put simply, without Purkinje cells, an animal loses its sense of space and distance, making balance and coordination difficult. In most cases, the neurons begin to die off shortly after the animal is born and the condition is noticable when the animal is less than six months old, though sometimes the onset of symptoms is gradual and the animal is much older before the owner or caretaker notices a problem.
CA cannot be prevented, other than by selective breeding to avoid the gene, and it cannot be cured. In addition to dogs and horses, there also have been cases of cerebellar abiotrophy in Siamese Cats; in Angus, Polled Hereford, Charlois and Holstein Friesian cattle; Merino and Wiltshire sheep; and Yorkshire pigs.
Other terms used
Cerebellar abiotrophy in horses was originally thought to be a form of cerebellar hypoplasia and was described as such in older research literature. The condition in Kerry Blue Terriers is sometimes called progressive neuronal abiotrophy (PNA). There are diseases that cause other types of cerebellar degeneration, but the loss of Purkinje cells is a clear way to diagnose CA.
A young Arabian horse with cerebellar abiotrophy, showing stiff awkward gait, and upper range of unnatural head bob. Symptoms of cerebellar abiotrophy include ataxia or lack of balance, an awkward wide-legged stance, a head tremor (intention tremor) (in dogs, body tremors also occur), hyperreactivity, lack of menace reflex, stiff or high-stepping gait, coarse or jerky head bob when in motion (or in very young animals, when attempting to nurse), apparent lack of awareness of where the feet are (sometimes standing or trying to walk with a foot knuckled over), poor depth perception, and a general inability to determine space and distance. The symptoms are, when taken as a group, fairly unique and not easily mimicked by other illnesses, though certain types of neurological injury and infection do need to be ruled out. However, verifying the diagnosis in terms of laboratory evidence is only possible by examining the brain post-mortem to determine if there has been a loss of Purkinje cells.
Most affected animals have normal intelligence and mildly affected animals can, in theory, live out a normal lifespan. However, affected animals are accident-prone, and for this reason many affected animals, particularly horses, are euthanized for humane reasons. Dogs may need lifetime assistance with tasks such as climbing stairs. Horses may experience difficulty stepping up and over objects, run into fences, fall easily, and even if allowed to mature to full growth, are generally considered unsafe to ride.
In horses, the symptoms may worsen from the time of onset for six to 12 months, but if not severe enough to mandate euthansia, they stabilize over time. In some dog breeds, symptoms appear to progressively worsen, but research is not consistent on this point. There also is some evidence that affected animals partially compensate for the condition by cognitively learning alternative methods for moving or to determine distance, and thus appear to improve because they become less accident-prone.
Cerebellar abiotrophy in horses
Cerebellar abiotrophy (CA) is best known as a condition affecting Arabian horses. It has also been observed in the Miniature horse, the Gotland Pony, and possibly the Oldenburg. Most foals appear normal at birth, with symptoms noticable at an average age of four months, though there have been cases where the condition is first observed shortly after birth and other cases where symptoms are first recognized in horses over one year of age.
In horses, CA is believed to be linked to an autosomal recessive gene. This means it is not X-linked, and the gene has to be carried by both parents in order for an affected animal to be born. Horses that only carry one copy of the gene may pass it on to their offspring, but themselves are perfectly healthy--without symptoms of the disease.
There currently is ***no DNA test ***for CA in horses, though there is ongoing research at the Veterinary Genetics Laboratory at the UC Davis School of Veterinary Medicine. ***SEPT 2008 UPDATE*** THERE IS A SCANNING GENETIC MARKER TEST NOW AVAILABLE
at UC Davis.
Cerebellar abiotrophy in dogs
CA has been seen in the Australian Kelpie, the Gordon Setter, Border Collie, Labrador Retriever, Airedale, English Pointer, Scottish Terrier, Kerry Blue Terrier, Miniature Schnauzer, and other breeds. Onset varies by breed of dog. In a few breeds, Purkinje cells begin to die off shortly before birth, and pups are born with symptoms. Most dog breeds prone to the condition begin showing symptoms between 12 weeks and six months of age. In a very few breeds, symptoms do not appear until adulthood or even middle age.
In dogs, CA is also usually an autosomal recessive gene, but in a few breeds, such as the English Pointer, the gene is ######-linked.
Bibliography (available on line)
Baird JD, Mackenzie CD. "Cerebellar hypoplasia and degeneration in part-Arab horses."
Aust Vet J. 1974 Jan;50(1):25-8.
Bjorck, G., Everz, K.E., Hansen, H.-J. and Henricson, B., 1973. Congenital cerebellar ataxia in the Gotland pony breed.
Zbl. Vet. Med. [A] 20:341-354.
Blanco A, et. al. "Purkinje cell apoptosis in arabian horses with cerebellar abiotrophy."
J Vet Med A Physiol Pathol Clin Med. 2006 Aug;53(6):286-7.
DeBowes R.M., et. al. "Cerebellar abiotrophy." Vet Clin North Am Equine Pract. 1987 Aug;3(2):345-52. de Lahunta, A. "Abiotrophy in domestic animals: a review." Can J Vet Res. 1990 January; 54(1): 65–76. Fox, J., et. al. "Cerebello-Olivary and Lateral (Accessory) Cuneate Degeneration in a Juvenile American Miniature Horse."
Gerber H, Gaillard C, Fatzer R, Marti E, Pfistner B, Sustronck B, Ueltschi G, Meier HP, Herholz C, Straub R, Geissbuhler U, Gerber V. "Cerebellare Abiotrophie bei Vollblutaraber-Fohlen" (Cerebellar abiotrophy in pure-bred arabians)
[German]. Pferdeheilkunde 1995;11:423-43;
Palmer, A.C., Blakemore, W.F., Cook, W.R., Platt, H. and Whitwell, K.E. "Cerebellar hypoplasia and degeneration in the young Arab horse: clinical and neuropathological features."
Veterinary Record 93:62-66 (1973)
ADDITIONAL READING: (Sponseller & Gerber et al.are the most informative from a layperson's point of view ~ szedlisa)
Sponseller, Brett A.,"A pedigree analysis of cerebellar cortical abiotrophy in the Arabian horse", Cornell University:Seminar SF610.1 1994 no.9472;
RO Waelchli and F Ehrensperger, "Two related cases of cerebellar abnormality in equine fetuses associated with hydrops of fetal membranes ",
Veterinary College, University of Zurich, Switzerland. The Veterinary Record, Vol 123, Issue 20, 513-514 F.O.A.L.
Fight Off Arabian LethalsVetGen
Veterinarian Genetic Services [New Site] VGL - Veterinarian Genetics Laboratory - UC Davis (University of California at Davis)Please note that the earlier studies in the 60s called CA 'cerebellar hypoplasia' until it was discovered that CH developed in the unborn fetus and CA developed starting at 2 or 3 weeks of age. Bret Sponseller based much of his study on his father's , Max Sponseller, extensive research in the mid 60s and published in 1967. They were working basically with a large east coast breeding herd which had lost 8 % of their foal crop and 6% the following year. Gerber et al in 1995 were working with the Finnish Registry as well as Belgium breeders, concentrating on Polish, Russian, Egyptian, Spanish, and Crabbet lines with 793 horses in their study with a 18.8 % foal loss in 1992 alone.
It is the son of the late Prof. Dr. H. Gerber, PD Dr. med. vet. Vincent Gerber, PhD, DACVIM, DECEIM, FVH, Head of Equine Internal Medicine of the Equine Clinic, Dept. of Veterinary Clinical Studies, Vetsuisse-Fakulty, University of Berne, who has initiated this present research project on Cerebellar Abiotrophy. Apparently research of this kind is adequately funded in Switzerland as there has been no hesitation whatsoever. They have already been recieving completed questionarries and samples and are extremely appreciative..
Keep them coming people!!
And please feel free to ask questions...
Edited by szedlisa, 26 November 2008 - 12:47 PM.