Cerebellar Hypoplasia in Dogs

The symptoms of cerebellar hypoplasia are often not noticed at birth, and may not be noticed until the pet begins to be more active from around 6 weeks of age. Incoordination, jerky movements, and tremors may indicate the condition. 

Although there is no treatment for this disorder, often pets can go on to live quality lives. As this disorder can present similarly to other conditions it is important to discuss any concerns you may have that your pet is suffering from this disorder with your veterinarian.

The cerebellum is the part of the brain responsible for coordination, balance and depth perception. Cerebellar hypoplasia is a congenital disorder in which the cerebellum is not completely matured at birth. This can be caused by a genetic disposition that affects some canine breeds or a number of conditions affecting the pregnant bitch, such as infection, poisoning, and malnutrition.

This condition is often noticed from about 6 weeks of age, as dogs begin to gain more movement. This disease is characterized by its non-progressive cerebellar signs. The symptoms your pet suffers from can vary greatly between cases. The symptoms include: 

• Nystagmus
• Incoordination 
• Ataxia and dysmetria 
• Intention tremor (tremor that increases at the end of a deliberate movement) of the head and eyes
• Wide stance 
• Disequilibrium (the sensation of being off balance)

In order to understand the symptoms your pet may be suffering from it is important to understand the role of the cerebellum in the canine. The cerebellum is located in the lower part of the brain and is part of the metencephalon. This part of the brain is responsible for coordinating muscle activity and establishing muscle tone. Therefore, disorders of this structure may prevent it from functioning properly, causing symptoms such as head tremors, incoordination of the limbs and abnormal posture. 

This condition most commonly affects the following breeds

• Chow chows
• Airedales
• Irish Setters
• Boston Terrier
• Irish Setters

As well as a genetic disposition this condition can be caused by intra-utero infection such as herpes virus, environmental toxins, or poor nutrition during pregnancy.

Your veterinarian will perform a full clinical examination, including a neurological examination, on your pet and discuss his history with you. Factors such as the age of your pet when symptoms were first noticed and your pet’s breed may be considered diagnostic features. Your veterinarian may choose to utilise magnetic resonance imaging (MRI) of the brain to confirm the condition; however, often the diagnosis is made from presenting symptoms that do not worsen or change and a negative result to parvovirus testing. In post-mortems of animals suffering from this disease, the condition may be seen by a symmetrically smaller cerebellum.  

It is important to differentiate this condition from another cerebellar disease, cerebellar degeneration or cortical abiotrophy. This disease may be suspected as similar symptoms present at a similar age, between 4 - 16 weeks of age. Unlike cerebellar hypoplasia, this disease is progressive due to ongoing reduction in cell populations in the cerebellum. 

Other cerebellar diseases that may need to be ruled out include: 

• Inflammatory diseases, such as meningitis
• Toxin ingestion 
• Trauma during birth or early life
• Metabolic disease that may have degenerative effects

Unfortunately, there is no treatment for this disease, although many animals who are born with this condition make excellent companion pets. Due to the nature of the disease the symptoms should not worsen for your pet.

To manage this condition for your pet, it is vital that you understand your pet’s physical limitations, your veterinarian will be able to discuss these with you. As your pet may have difficulty controlling movement, you may need to assist your pet when eating and drinking.

For many pets with this condition self-trauma is the most common complication. In order to reduce the incidences of self-harm, providing your pet with a safe environment is an essential part of the management of this disease. Due to the imbalance and wide stance, stairs and uneven ground may cause a hazard. A non-slip, flat surface is an ideal environment for your pet. 

In very severe cases of the disease, the reduced life quality caused by this condition may result in your veterinarian recommending euthanasia for humane reasons. As this is often a genetic condition it is important that the parents of this pet are not bred further due to the chance of future litters inheriting this condition.