Cerebellar Hypoplasia in Dogs and Cats

Overview of Cerebellar Hypoplasia in Dogs and Cats

The brain is divided into portions: the cerebrum (larger front section), the cerebellum (small portion at the back of the brain), and brain stem (which extends down to the spinal cord). The cerebellum can be affected during development in dogs and cats or affected later in life by progressive genetic diseases.

Two main types of diseases affect the cerebellum: hypoplasia and abiotrophy. Cerebellar hypoplasia is a condition where the cerebellum does not develop correctly, whereas cerebellar abiotrophy is when the cerebellum develops normally, but ages prematurely and degenerates.

Cerebellar Hypoplasia in Cats

Cerebellar hypoplasia is seen in kittens that are infected in utero with feline panleukopenia (FPV). Feline panleukopenia infects pregnant queens and is transmitted to their fetuses. Panleukopenia has an affinity for rapidly growing cells and most commonly affects the cerebellum and retina in developing kittens. Cerebellar hypoplasia is a stagnant disease, meaning that once developmental damage has occurred, no further damage or degeneration will manifest. Kittens are affected from birth and it persists for their entire life, but is not progressive.

Cerebellar Hypoplasia in Dogs

Congenital cerebellar hypoplasia has been documented in dogs, mainly in the Chow Chow breed. The underlying pathophysiology is suspected to be secondary to selective hypoplasia (lack of development) of the cerebellum. Cerebellar hypoplasia has also been diagnosed alongside lissencephaly, an in utero developmental defect where the brain is smoother than normal, which is mainly seen in Irish Setters and Wire Fox Terriers.

Dandy-Walker syndrome, an anatomical abnormality, is also seen as a secondary disease to cerebellar hypoplasia, hydrocephalus, and 4th ventricle dilation. This syndrome is most commonly seen in Toy Fox Terriers.

Cerebellar Abiotrophy in Dogs

Cerebellar abiotrophy is different from cerebellar hypoplasia in that the cerebellum fully develops in utero and puppies are clinically normal at birth. Unfortunately, at some point in their lives, the cerebellum degenerates and clinical signs develop. This genetic disease is seen earliest in Samoyeds and Beagles, usually as young puppies when they are initially starting to walk. In Australian Kelpies, Rough Collies, and Kerry Blue Terriers, the clinical signs can be seen around 4 – 16 weeks. Breeds in which clinical signs are noted when they are young adults are Brittany Spaniels, Old English Sheepdogs, and Gordon Setters. Although the time of onset of clinical signs may differ from hypoplasia, clinical signs are very similar. Dogs with cerebellar abiotrophy can have progressive clinical signs throughout their lives.

Clinical Signs

Signs will vary in severity and may improve slightly as a pet tries to overcome its deficiencies.

Signs of cerebellar hypoplasia and abiotrophy in dogs and cats include:

• Head bobbing
• Unsteady or swaying body
• Exaggerated movements (feet may be lifted high when taking steps)
• Limb tremors (rhythmic, “to and fro” involuntary movements)
• Wide-based stance
• “Spastic” walking
• Incoordination
• Accentuated movements when trying to eat or walk (intention tremors)

Diagnosis

Diagnosis of cerebellar diseases are commonly made based on age of the animal, breed, and clinical signs. Additional tests are usually recommended to rule out other neurological conditions.

A complete blood count (CBC), biochemical profile, and urinalysis are recommended in all cases. The results are generally normal with this disease. It is important to rule out metabolic disorders such as hypoglycemia (low blood sugar) or kidney disease. Juvenile animals can be born with liver shunts (abnormal vessels in their livers) that can cause neurological signs. Blood work is useful in ruling out these conditions.

If other possible diagnoses are being considered, tests such as chest and abdominal radiographs (X-rays) may be recommended. They are most often within normal limits.

Definitive diagnosis of cerebellar hypoplasia is performed by further imaging of the brain through an MRI. Cerebellar hypoplasia can also be noted on autopsy reports after animals have passed away.

Treatment of Cerebellar Hypoplasia in Dogs

Unfortunately, there is no treatment for cerebellar hypoplasia or abiotrophy.

Helpful Tips for Home Care

Because patients that have cerebellar disease are unsteady on their feet, making environmental modifications can be helpful in managing the disease.

A few helpful environmental changes include:

• Limiting Stairs or Heights. Using baby gates or playpens can prevent falls and injuries. If stairs are in the animal’s environment, they should only be used with supervision and help.
• Walking Dogs with Harnesses. Harnesses can allow extra help when walking and steady animals when off balance.
• Using Larger Litter Boxes. Small litter boxes can be challenging for cats with cerebellar hypoplasia. Large boxes with a low entrance will be easier to navigate and help avoid accidents.
• Adding Mats and Slippery Flooring. Placing mats or non-slip rugs around your home can help pets get up and around their environment. Slippery floors can exacerbate clinical signs.
• Modifying Feeding Options. Try different shapes and heights of food and water bowls to optimize your pet’s comfort.
• Grooming Hair Coats. If your pet has long hair, especially around their hind end, keep them well groomed and hair short to manage cleanliness.
• Keeping Claws Intact. Cats with cerebellar hypoplasia use their claws to help with balance and stability. Declawing takes away their ability to stabilize themselves.
• Keeping Pets Indoors. For obvious reasons, cats with cerebellar hypoplasia should be kept indoors only. They are at a higher risk of injuring themselves and have a decreased ability to get away from dangers or predators.

Prognosis

Long-term prognosis is based on the severity of an animal’s clinical signs. Most pets that have cerebellar hypoplasia can live a long and healthy life. Since clinical signs are stagnant with cerebellar hypoplasia, they are similar throughout a pet’s life. With cerebellar abiotrophy, clinical signs are progressive and may have a worse prognosis based on the severity of the disease.
There are multiple resources available, including internet blogs and Facebook groups, that foster a support system for families with affected pets. These are amazing sources of information if you have a pet with special needs.