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Health - Cerebella Ataxia
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An Emerging Neurological Problem in American Staffordshire Terriers:
Spinocerebellar or Hereditary Ataxia (The following article has been edited and was originally written by Dr. Natasha Olby) The Problem
As with all pure bred dogs, American Staffordshire terriers exhibit some health problems that are most likely the result of genetic defects. Recently, the Staffordshire Terrier Club of America's health committee has noticed that there are increasing numbers of dogs developing a drunken, staggering gait and balance problems as they get older. This is a particularly serious disease, as dogs do not exhibit signs until well into adulthood, after they have been bred. Current research indicates that this is a genetic disorder. The Symptoms
This disease affects a particular part of the brain called the cerebellum. The cerebellum is closely associated with the vestibular system and together these parts of the brain control coordination of movements. There are many different diseases that can affect these areas of the brain and therefore produce similar signs. Infection of the middle ear, trauma, viral infections, tumors, autoimmune disorders and bacterial disease can also cause vestibular and cerebellar signs. However, the order and rate in which signs develop in dogs with this particular syndrome are characteristic of the disease. Both male and female dogs are affected and signs may start from 2 - 5 years of age. Initially, the signs are very subtle and include clumsiness and an occasional sway of the body when making sudden movements. Agility dogs, for example, may develop problems with a particular obstacle that they could previously negotiate without difficulty. Dogs may trip and fall when negotiating steps or moving quickly. As the disease progresses, the clumsiness becomes more pronounced: dogs may fall over when they shake their head and often have an obvious body sway when they move their head quickly. Male dogs may lose their balance while lifting their legs to urinate. When moving in a controlled fashion in a straight line they may still look normal, but when turning corners, chasing balls, and rushing for their food, the mistakes become obvious.
If the dog's eyes are watched carefully, it is noticed that sudden movements of the head cause rapid flicking of the eyes (nystagmus), either from side to side, round in circles or vertically. Rolling the dog onto its back is the most reliable way of eliciting these eye movements and they usually last from a few seconds to about one minute.
Other early signs of the disease may include sudden episodes of collapse, with stiffening of all 4 legs, the neck and the body that last for a few seconds. With time, the dogs have more and more difficulty walking because of lack of coordination of their legs rather than weakness. The AmStaf may also lose weight as the dog has balance difficulties reaching his food bowl.
Please remember that we are very early in our data collection process. The age of onset, symptoms, and progression varies from dog to dog. The above descriptions are general signs of hereditary ataxia. Your dog does not have to have every characteristic listed in order to be considered affected. The one similarity that all the dogs have shared thus far has been balance problems.
The Prognosis
The progression of the disease varies from dog to dog. For many AmStafs, the signs develop slowly. The STCA health committee considers hereditary ataxia a "deadly" disease since most AmStafs cannot live out a normal lifespan and must be humanely euthanized. Most are not able to function past the age of 7 or 8. One note: if anesthesia is performed for some reason (e.g. a routine dental), it may accelerate deterioration. We have witnessed dogs with minimal signs waking up from anesthesia extremely unbalanced with obvious nystagmus. These signs improve somewhat in the days after anesthesia, but the dog does not recover to the level it was at prior to anesthesia.
The Diagnosis
There is now a DNA test available from Antagene laboratories in France, via a simple oral swab the Laboratory is able to identify the genetic markers that carry the disease.
Cerebellar Ataxia is inherited as a autosomal recessive trait, which means a dog must have two defective copies (one from each parent) to be affected. A dog once tested will be classified as one of the following three classifications: Clear - 2 normal copies of the implicated gene - the dog does not have ataxia, is not a carrier for ataxia and cannot produce carrier or affected offspring. Carrier - 1 normal copy and one defective copy of the implicated gene - the dog is not affected by ataxia but is a carrier of the gene. He can pass the gene onto his offspring. Affected - 2 defective copies of the implicated gene - the dog has ataxia, and will pass the gene onto offspring. The approximate breakdown rate of breeding a clear, carrier and affected dog is as follows: Clear to Clear - 100% Clear Clear to Carrier - 50% Clear, 50% Carrier Clear to Affected - 100% Carriers Carrier to Carrier - 25% Affected, 25% Clear, 50% Carriers Carrier to Affected - 50% Affected, 50% Carriers Affected to Affected - 100% Affected It should be noted if 2 Clear dogs are bred together, the resulting pups are clear by parentage and do not require testing. If you are purchasing a Amstaff pup, please ask the status of the parents Ataxia test results.
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