[szedlisa]

Greetings to All Arabian Horse Breeders and Owners:


Cerebellar Abiotrophy is a neurological disease, most often noted in newborn foals of approximately 3 weeks to 4 months of age. The most notable symptoms are a palsey-like head shaking (called intention tremors), the lack of a normal blink response although vision is correct, and an awkward exaggerated form of action with the forelimbs often similar to a military goose-step or high elevation used to cross over a very low object called hypermetric action. As these affected foals will often run into things or fall down- sometimes causing head injuries, their condition can be mis-diagnosed as injuries from a blow to the head or neck, making the true neurological condition go unnoticed.

Cerebellar Abiotrophy (CA) is being recognized in all bloodlines of the arabian horse. Suspected to be an autosomal recessive defective allele, it can be passed forward through several generations without re-appearing. It is not a lethal gene. It does however make the horse generally unfit for riding or driving. Most affected horses are euthanized before they cause severe damage to themselves or to their handlers because of their inability to control their own balance.

More samples are needed to identify the specific allele or combination of alleles and develop a test for Carrier horses. All information is kept private to protect any of the horses and their owner/breeders respective breeding programs. Cases of actual affected CA have been the requirement in the past, but now they want samples from any related family members as well. It is in this realm where we could really be of help in pushing research on CA forward. If you have had a CA foal in the past, which has already been euthanized but still have what appears to be perfectly normal syblings or otherwise related family members, these too are important for this research.


It is my hope and goal for 2007 that with this concentrated effort of your welcomed participation that the markers for CA will be identified and a test will be developed.

Please help us obtain these goals.

Plase contact Dr. Cecilia Penedo, PHd at UC Davis for Marker Scanning Test:
http://www.vgl.ucdavis.edu/services/horse.php

The Swiss research team of Gerber and Leeb have closed their research.

Lisa

This post has been edited by szedlisa: 25 February 2009 - 07:18 AM

[SandStone]

I have never heard of this disease. Is this a new disease? Perhaps it is a condition previously reported, but was yet unnamed.

Scary, to say the least! Certainly, any animal exhibiting these symptoms should be checked. Thanks for the information.

[aramar]

Here we go again, Lisa. Better put your survey on this site.

[Robin in MI]

THAT is a scarey disease! 800-1000 lbs of incoordination? dangerous!


Robin in MI

[AccentoArabians]

Lisa,

Thank you so much for sharing this information with us. My cousin had an Arabian filly a few years back that we had to put down because she was diagnosed as having wobbles. We didn't do any x-rays since it was so bad that she had to be put down from her lack of cordination. They say that Arabians are one of the top horses diagnosed with wobbles. Almost makes you wonder if some them diagnosed with wobbles don't actually have this disease.

[Shan]

Thanks for sharing this..I read this on another forum as well

[SandStone]

So the Cerebellar Abiotrophy condition is commonly known as "wobbles"?

Well, sure I've heard of wobbles! Who hasn't?

I thought this was a newly discovered condition. Glad it isn't.

Guess I'd better work on my "scientific name recognition" memory.

[Marketing]

Equine cerebellar abiotrophy (CA) is a genetic, neurological condition found almost exclusively in Arabian horses. Results from breeding experiments carried out at UC Davis indicate a recessive mode of inheritance for this condition. This means that a horse can "carry" the disease gene but not be affected by it. However, breedings between two carrier horses will produce an affected foal 25% of the time.

The incidence of CA in Arabians is unknown but evidence from affected foal's pedigrees indicates that the disease gene is present in popular bloodlines. Personal communications with veterinarians and Arabian horse breeders suggest that this disease affects a significant number of horses every year. Without a direct genetic test, there is no way to know how many horses are carriers or whether a particular mating creates a risk for an affected foal. Dr. Cecilia Penedo and her research team at VGL are working to identify the gene responsible for CA. In 1985, the late Dr. Ann Bowling, a renowned horse geneticist and researcher at VGL, started a small breeding herd based on carrier and affected horses donated to the UC Davis veterinary hospital. Using DNA from these horses and their offspring, as well as DNA that we collected from other small families producing CA foals, we have obtained promising preliminary results. However, the number of horses is still small. Additional samples of affected horses and their families would greatly improve our chances of locating this gene and developing a diagnostic test for CA.

Owners interested in assisting us with our research are an invaluable resource and we welcome all communications. All conversations and identities of owners, farms, and horses are kept strictly confidential. If you suspect that you have an affected foal, please contact Dr. Penedo.


Symptoms of CA
Foals affected with CA appear normal at birth. Around six weeks of age (although sometimes as late as four months), the disease causes the death of neurons in the cerebellum of affected foals, leading to head tremor (intention tremor) and a lack of balance equilibrium (ataxia). Affected horses may show exaggerated action of the forelegs, a wide-based stance, and be unable to rise from a reclining position. They tend to startle easily and often fall due to ataxia. The neurological problems may not be apparent to owners and are frequently thought to be a consequence of a fall rather than the cause of it. CA symptoms vary in severity. Some foals show very severe symptoms, including the exaggerated gaits and a dramatic lack of balance. Others have little more than the head tremor, which may only manifest itself during goal-directed movement. Regardless of the severity of the symptoms, CA foals are often euthanized or restricted to life as pasture pets, as they are never coordinated enough to be ridden safely. They are also a danger to themselves because the condition predisposes them to accidents and injury.

Veterinarians can perform a series of neurological tests to determine if symptoms are consistent with CA.

Histopathological Indicators of CA
Positive diagnosis of CA is only possible through post-mortem histological examination of cerebellar tissue. The photos below contrast the cerebella of a normal and an affected horse (an affected subject in our CA genetic mapping resource).

Normal Cerebellum

The normal cerebellum is divided into two layers: the inner layer, known as the granular layer, and the outer layer, known as the molecular layer. Purkinje cells are large neurons that lie on the border between these two layers. They carry electrical signals from the molecular to the granular layer, where the signal is then transmitted to the body. They carry all messages generated by the cerebellum and have control over the refinement of movement and coordination.

Cerebellum affected with CA

In horses affected with CA, the Purkinje cells begin to degenerate soon after birth. Purkinje cells are closely associated with the granular cells in the cerebellum and their death causes a subsequent loss of granular cells as well. Remaining Purkinje cells are usually small and shrunken. Without the Purkinje cells, the two layers of the cerebellum become indistinct. This image was taken of the cerebellum of a 3-year-old Arabian colt affected with the disease

[aramar]

Excelent post. Dr. Bowling and her crew at UCD were the first I knew who really went to great lengths to study this. I know that it is still in the program there but money is the culprit that slows things down. I'm hoping there is some new interest and that Arabian horse breeders will be open to participating.

PS. Wobbles is not the same affliction and it is found in other breeds. I knew an Appy breeder who had a stallion that produced it and she gelded him and returned all the stud fees to the mare owners that had bred to him.

[szedlisa]

P.A.S.S.
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:

Cerebellar abiotrophy
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.

Symptoms
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.


References

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 [1988]

F.O.A.L. Fight Off Arabian Lethals
VetGen 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...

Lisa

This post has been edited by szedlisa: 26 November 2008 - 03:47 PM