Neurological Inherited Conditions

Topic: Genetic Conditions in Dogs

Filed under Dogs

Tags: Neurological Disorder, Ataxia, Deafness, Wobblers Syndrome, Hydrocephalus

 

Neurological conditions are those conditions that affect the central nervous system or the functioning of the muscles in relation to nerve impulses. Many of the conditions that can occur in dogs also occur in humans as well as other animals, which means there is considerable research and information available on these conditions. Just as with humans, there are medications that can be used to treat some of the neurological conditions, such as epilepsy, but others are progressively degenerative and usually result in death in a relatively short period of time. This is largely due to the brain's control over all the body processes including breathing, circulation and movement. When any or all of these systems become dysfunctional there is a greater risk to the dog to develop other related health problems that tend to make successful treatment and full recovery much more challenging.

Ataxia is a relatively uncommon neurological condition that occurs either before or shortly after the puppy is born. It is also known as cerebellar abiotrophy and is caused when the brain cells, particularly in the cerebellum, begin to degenerate and die for no apparent reason. It is an inherited disorder and while rare is found in a great number of breeds, most that are working or herding dogs. The breeds affected by ataxia include the Kerry Blue Terrier, Rough Coated Collie, Miniature and Toy Poodle, Gordon Setter, Airedale, Australian Kelpie, Brittany Spaniel, Border Collie, Labrador Retriever, German Shepherd and Bernese Mountain Dog. It is occasionally seen in almost any other breed and also in mixed breed dogs.

The first signs of ataxia are usually noticeable before the puppies reach 12 weeks of age. These pups have very poor coordination and may walk with a very high stepping gait, seem to have a lack of balance, be unaware of how they are moving and stand with their legs splayed very wide apart. They may have tremors or seizures that become progressively worse and loss of muscle control over the bladder and bowels is not uncommon. They may become blind, become aggressive or even stop eating completely.

Unfortunately for the puppies that inherit this condition there is no cure or treatment. They are typically euthanized shortly after the condition starts to interfere with the puppy's ability to move around and have a normal life. All siblings in the litter with a puppy with ataxia should be spayed and neutered and the breeding pair should also be removed from the breeding program because of the possibility that one or both are carriers. This may vary depending on the breed as some cases of ataxia are linked to a sex gene which means only male puppies will exhibit the condition but the females will be carriers.

Deafness in either one or both ears is often a neurological inherited condition, especially in white coated and merle colored dogs with blue eyes. The Dalmatian, Shetland Sheepdog, Border Collie, Dachshund, Great Dane, Staffordshire Terrier, Greyhound, Whippet, West Highland White Terrier and several other breeds with these colorations are all at some risk. In some breeds the deafness will be congenital or present at birth, and in others the dogs will have progressive hearing loss in one or both ears as they mature.

Deafness in one ear is often not even recognized by the owner unless the other ear is injured or becomes infected, cutting down on the dog's ability to hear. When puppies are born deaf or if they go deaf as they age the dog will adjust, however you will need to use hand signals to train and the dogs will always be at risk when out of the yard or off the leash. Only walk these dogs off leash in non-traffic areas and avoid putting them in situations where hearing loss could be a safety risk.

Wobbler Syndrome is an inherited malformation of the small vertebrae of the neck that puts increasing pressure on the spinal cord as the puppy grows. The disks between the vertebrae are compressed and may actually cause pressure points on the spinal cord that prevent the movement of the limbs, resulting in a wobbling type of gait.

There are a great number of breeds that can inherit Wobbler Syndrome but it tends to be most common in the very large breeds. Great Danes, St. Bernards, Borzois, Irish Wolfhounds, Great Pyrenees, Rottweilers and Bull Mastiffs may all display this condition within specific lines. Almost any other large size dog can also have this neurological condition, especially in mixed breedings between known carrier breeds.

Generally the signs of Wobbler Syndrome start out looking relatively like ataxia. There is marked lack of coordination in both hind legs, which gradually becomes worse and spreads to the front legs. The dogs often cannot easily either get up or lie down and often seem to move very stiffly and wobble from side to side with their gait. Early treatment that braces the neck and administration of steroids to stop inflammation and reduce pressure on the spinal cord can be effective in minimizing the progression of the condition. Surgery may be an option depending on where the compression is occurring in the neck and how significant the malformation of the spine is at the time of diagnosis.

Hydrocephalus is often known as water on the brain, but it is actually a build of the cerebrospinal fluid within the skull. It can be present when the puppy is born or it can develop later in life due to an infection or blockage of the normal movement of cerebrospinal fluid. It is most common in toy breeds and breeds with the very short muzzles, known as the brachycephalic dogs. Breeds most at risk include the Pug, Shih Tzu, Lhasa Apso, Pomeranian, Yorkshire Terrier, Chihuahua, Boston Terrier, Maltese, Cairn and Manchester Terriers as well as the English Bulldog and the Toy Poodle. For many years this was a problem in Doberman Pinschers but it has been corrected through specific controlled breeding programs to eliminate the skull malformation that was contributing to the condition.

The condition, if severe, will result in the death of the puppy shortly after birth. In less severe cases the puppy may survive but have coordination problems, seizures, poor growth, inability to learn and a domed or larger than typical skull due to the build up of outward pressure.

There are options to surgically place a shunt to drain off fluid from the brain, and the use of diuretics and steroids is often used with varying effectiveness. Typically if the puppy survives to about 2 years of age he or she will stabilize and adjust, however they will always have difficulty in learning and may be prone to other neurological conditions including seizures throughout their life.

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