Cerebellar Abiotrophy (CA/ataxia) in the Australian Kelpie by Kathy Gooch
The most prevalent genetic disease to affect the Australian Kelpie is CA (cerebellar abiotrophy). Because the ramifications of this condition are universally widespread it is the most significant genetic disorder in the breed. It is also one which is not openly discussed by breeders. Affected dogs are usually destroyed, with no necropsy being done and the carrier parents are bred to other dogs, only to perpetuate the carrier status. Hopefully this article will answer questions regarding this condition and illustrate the need for a DNA test and co-operation amongst breeders with regards to submitting samples. What is cerebellar abiotrophy? The cerebellum is the part of the brain that regulates the control and coordination of movement. In this condition, cells in the cerebellum mature normally before birth, but then deteriorate prematurely causing clinical signs associated with poor coordination and lack of balance. The Purkinje cells in the cerebellum are primarily involved; cells in other areas of the brain may also be affected. How is cerebellar abiotrophy inherited? An autosomal recessive mode of inheritance has been confirmed or is strongly suspected for the abiotrophies listed below, with the exception of x-linked cerebellar ataxia in the English pointer, which has an x-linked mode of inheritance. This means BOTH parents must be carriers or affected. Carriers exhibit no symptoms of the disease, while affected dogs can exhibit a range of symptoms from mild to severe. There seems to be much confusion with regards to how CA is inherited in the Australian Kelpie. Click here for more detailed information. What breeds are affected by cerebellar abiotrophy? Neonatal cerebellar abiotrophy (very rare) - Affected cells start to degenerate before birth, so that signs of cerebellar dysfunction are present at birth or when the pup first walks. Beagle, Samoyed Postnatal cerebellar abiotrophy - Cells in the cerebellum are normal at birth and begin to degenerate at variable times thereafter. Australian Kelpie, Border Collie, Labrador Retriever - Clinical signs can be first seen at 6 to 12 weeks, and the condition can worsen quickly (over a few weeks). Or clinical signs can be subtle and not appear until the animal is older. Cerebellar and extrapyramidal nuclear abiotrophy - Cells in other regions of the brain deteriorate as well. For many breeds and many disorders, the studies to determine the mode of inheritance or the frequency in the breed have not been carried out, or are inconclusive. We have listed breeds for which there is a consensus among those investigating in this field and among veterinary practitioners, that the condition is significant in this breed. What does cerebellar abiotrophy mean to your dog & you? The cerebellum is the part of the brain that regulates the control and coordination of voluntary movement. The clinical signs of cerebellar dysfunction in affected dogs may include poor balance, a wide-based stance (feet planted far apart), stiff or high-stepping gait, apparent lack of awareness of where the feet are (standing or walking with a foot knuckled over), and head or body tremors. These signs worsen either quickly or slowly (see breed list above). Affected dogs may become unable to climb stairs or stand without support. They have normal mental alertness. Clinical signs can come in varying degrees of severity from mildly affected egg; slight head tremor, slight propping in the rear end to falling over and total loss of control. Symptoms usually appear at 6 to 12 weeks. Some dogs adapt to the dysfunction and show little disability. Where other regions of the brain are also affected, you may see signs such as behaviour change (loss of house training, aggression), confusion, blindness, and seizures. How is cerebellar abiotrophy diagnosed? The clinical signs are suggestive of cerebellar disease, particularly if they are seen in a breed in which abiotrophy is known to occur. Your veterinarian will do tests to rule out other conditions that can cause similar signs. Unfortunately 100% diagnoses can only be determined upon necropsy of the brains of suspect animals. This re-enforces the need for a DNA test to determine carrier/affected status. How is cerebellar abiotrophy treated? There is no treatment for this condition. Dogs do not recover from this disorder and usually at some point (depending on the rate of the progressive deterioration that occurs), euthanasia becomes the best option. Breeding advice Affected dogs, their parents (carriers of the trait), and their siblings (suspect carriers) should NOT be bred. With x-linked cerebellar ataxia, only male pups are affected, and the mother is the carrier of the trait. But this is only in the English Pointer, not the Kelpie. CA has become a widespread problem in the breed. It is apparent that it is not just an Australian, American, or European problem. Because of the relative ease of importing a dog from Australia, a Rabies free country, it is now a global issue. CA is also in both the Working Kelpie and the Show Kelpie. More than one Working Kelpie line is affected. Dr. Don Robertson, a West Australian geneticist who studied the problem wrote in an article on CA in Kelpies for the Australian Veterinary Journal in 1989 “In the Kelpies studied here, the putative gene appears to have been inherited from several dogs which have been prominent in sheep dog trials and have been widely used for breeding. Consequently, an increase in the incidence of cerebellar abiotrophy in working sheepdog strains can be expected“. Unfortunately at present there are very few Working Kelpie pedigrees in which these lines do not appear. This once again exemplifies the need for a DNA test. It seems that the reason it does not appear that CA is a problem in Australia is the “shoot, shovel and shut-up attitude” No one talks about affected litters. They just disappear in a hole. Then the parents which are obviously carriers are bred to other dogs and if nothing shows up the pups are sold as “normal”. The unsuspecting buyer is than buying a possible carrier. Then the buyer purchases another dog from the same lines in the hopes of doing a line breeding. Then as bad luck would have it that dog is a carrier. These dogs are bred and BANG!!!!! You have a litter of affected pups. The ones showing symptoms are shot and the non affected ones sold and bred. Odds are they are carriers as well so the problem continues and continues and continues. Some of these carriers have been exported out of the country only spreading the problem. The issue with CA as is that it can appear at six weeks or at two or three years . This is a terrible loss to many people of a beloved pet, not to mention the time and money put into training a dog. If a DNA test was developed, affected individuals could be euthanized and carriers could be desexed and still used as working dogs. Also the non carriers of a litter could be bred and the positive traits of those lines still passed on with out the worry of genetic problems. If breeders think that they would lose money as a result of this DNA test, exactly the opposite would occur. If a pup was sold with a CA clear certificate the value of that pup would be greater than those without. Also because of the cost of export, breeders and buyers would be put in a position to have testing done before dogs left the country. Because the Kelpie has a relatively small gene pool to eliminate excellent carriers from the gene pool would be madness. The KEY is to KNOW THE STATUS of the dogs you are breeding.