Degeneration of the Cerebellum of the Brain in Dogs

In some dogs, an inherited condition can cause the neurons in the cerebellum to degenerate and die at a young age. This is called cortical cerebellar abiotrophy or often just cerebellar abiotrophy (CA). Veterinarians believe it is caused by a metabolic problem that affects the Purkinje cells in the cerebellum. As well as dogs, CA is found in horses and some other animals. In most cases, the disorder is inherited as an autosomal recessive trait, so both parents must carry the gene for a dog to develop symptoms. Versions of the disease have been found in a number of different breeds, especially Gordon Setters and Kerry Blue Terriers; however it remains a rare condition. The Purkinje cells in the cerebellum control balance, coordination, and space perception, so affected dogs usually have abnormal gait, uncoordinated movements, and balance problems. Most dogs with CA begin to show symptoms between 6 weeks and 3 months of age, but a few cases are present from birth and manifest as soon as a dog begins to move about. Occasionally symptoms do not develop until adulthood. Time of onset is often breed specific. CA is a progressive condition, so it will get worse over time. In most cases, dogs develop very severe symptoms and euthanasia is necessary. The progression may taper off for a period of time and, in few cases, dogs can live long lives with only mild coordination problems. There is no cure for CA.

Some puppies born with a normal cerebellum experience neural degeneration while they are still young. This is an inherited condition called cerebellar abiotrophy. Dogs have reduced movement control, balance issues, and falling. Symptoms get progressively worse over time.

See a veterinarian if you notice any of the following symptoms, especially in a puppy or a young dog.

• Uncoordinated movements (ataxia)
• Wide based stance
• Abnormal gait or staggering
• Balance problems
• Falling
• Involuntary eye movements (nystagmus)
• Head or leg tremor while attempting voluntary movement
• Periods of extreme muscle stiffness
• Seizures

Types

Two different cerebellum disorders can occur in young dogs.

Cerebellar abiotrophy is a progressive disease usually with juvenile onset. The cerebellum is normal at birth. Degeneration can begin shortly after and mainly affects the Purkinje cells of the cerebellum.

Cerebellar hypoplasia in contrast to CA, is a non-progressive disorder in which the cerebellum does not develop properly in the uterus. Symptoms are present at birth and don’t get worse with time. Depending on the severity of the symptoms, dogs can still make good pets.

The problem has been isolated in a number of different breeds, although cases remain rare. It could occur in any breed of dog.

Onset from birth to 6 weeks old

• Airedale terrier, Beagle, Rough Collie, Coton de Tulear, Finnish Harrier, Jack Russel Terrier, Irish Setter, Miniature Poodle, Rhodesian Ridgeback, Samoyed

Breeds with normal onset at 6-16 weeks old

• Australian Kelpie, Border Collie, Labrador Retriever, Airedale, English Pointer, Scottish Terrier, Kerry Blue Terrier, Miniature Schnauzer, Bernese Mountain Dog, Bull Mastiff, Coton de Tulear, Gordon SetterBreeds with adult or middle age onset

Breeds with adult or middle age onset

• American Staffordshire Terrier, Old English Sheepdog, Brittany Spaniel, Gordon Setter

CA is diagnosed symptomatically. The veterinarian will need to know your dog’s breed and family history as well as any recent injuries or trauma that could have caused the problem. The symptoms of Purkinje cell degeneration are fairly specific, but the veterinarian will still need to rule out other potential causes, especially a systemic infection or a CNS inflammatory disease. Blood and urine tests will be taken. In some cases cerebrospinal fluid will be tested and the vet may order an MRI of the brain. The cerebellum typically shows only minimal differences with CA, so MRI’s aren’t a good way of diagnosing the disease, but they can check for brain cancer or other problems that could be causing your dog’s symptoms. 

Differentiation between CA and cerebral hypoplasia can sometimes be challenging since both have very similar symptoms. The progressiveness of the symptoms as well as the time of onset can usually help to distinguish the two conditions. Since there is no cure for either, the veterinarian may simply suggest monitoring your dog’s symptoms to see if they get worse over time. A definitive laboratory diagnosis can only be made by a brain biopsy (rarely done) or examining a dog’s brain post-mortem. Significant degeneration in the cerebellum is usually found upon autopsy.

There is no effective treatment for CA. The veterinarian will tell you to monitor your dog’s symptoms and watch for signs of progression. Dogs with mobility problems are more prone to falling and injury, so you may need to limit your dog’s activity and protect against hazards like stairs. If your dog’s symptoms become too severe, the veterinarian will suggest euthanasia.

Dogs won’t recover from CA, but the condition can sometimes be managed depending on the severity of the symptoms. If the degeneration tapers off and becomes stable, dogs often learn to compensate and falling may decrease. In some cases, dogs can live for months or even years with only mild symptoms. This is rare, however; more commonly symptoms will progress rapidly and puppies will need to be euthanized while they are still quite young. You will need to monitor your dog and decide when the problem has become too severe and limiting.

Breeding of parents or siblings of affected dogs should be avoided since dogs can be carriers without showing symptoms. Careful breeding has reduced instances in breeds where the condition is well known, like Gordon Settlers and Kerry Blue Terriers.