Cerebellar Hypoplasia in Cats

Cerebellar hypoplasia (CH) is a congenital malformation of the cerebellum, which is the part of the brain responsible for balance and coordination. Cerebellar development stops in the uterus due to some external interruption. The most common source of this developmental abnormality is a maternal panleukopenia infection during pregnancy. Cerebellar hypoplasia is very unlikely to occur in kittens from vaccinated mothers. Severely affected kittens may not survive and there is no cure.

Symptoms typically become apparent by 3 weeks of age when the kitten starts to become more active. This differentiates cerebellar hypoplasia from conditions that lead to similar symptoms in adult cats which are more likely to be an emergency.

Various external factors can interrupt cerebellar development in kittens. Exposure to toxins, lack of oxygen to the brain (such as during a difficult birth), and head injury are all risk factors for CH.

The most common root cause of CH is transmission of feline panleukopenia virus from mother to kitten during pregnancy. Kittens born to unvaccinated mothers are at the highest risk of CH.

Other brain abnormalities, like hydrocephalus, may also be concurrently present.

Symptoms can vary between kittens of the same litter. Symptoms may not be noticeable until the kittens start to walk at 2-3 weeks of age. Kittens may be born without CH and develop symptoms later in the neonatal period if they are infected post birth.

The most common cause of cerebellar hypoplasia is maternal infection with feline panleukopenia virus during pregnancy. The virus is transferred from the mother to kittens in the womb. Feline panleukopenia virus can also infect kittens by the fecal oral transmission route in the neonatal period. The developing cerebellum is particularly vulnerable to the virus, and infection halts its development. Less common environmental factors such as toxins, lack of oxygen to the brain, and head injury can also cause cerebellar hypoplasia. Some cases have no identifiable root cause.

Symptoms vary from very mild to severe depending on how developed the cerebellum was prior to infection (or exposure to other risk factors). Kittens affected when the cerebellum is almost fully developed have mild signs. Kittens affected early in cerebellar development have more severe symptoms. Lack of progression of symptoms differentiates cerebellar hypoplasia from other types of cerebellar disease.

A presumptive diagnosis of cerebellar hypoplasia is made based on clinical symptoms and lack of progression of signs. Definitive diagnosis can only be made with a CT scan or after death.

There is no treatment for cerebellar hypoplasia. Keeping affected cats indoors for their safety is recommended. Managing the environment by providing non-slip mats and litter boxes with low entrances can help maximize quality of life.

Cerebellar hypoplasia is permanent but symptoms do not progress. Many kittens improve slightly as they learn to compensate. Quality of life depends on how severe the symptoms are. Mildly affected cats may have nearly normal life. Humane euthanasia is usually considered for severe cases.

Vaccinating queens prior to breeding prevents viral induced cerebellar hypoplasia. Cerebellar hypoplasia is not contagious. The virus that commonly causes cerebellar hypoplasia is highly contagious.

CH is uncommon in cats.

There is no treatment for cerebellar hypoplasia. Environmental management helps improve quality of life in some cases. Severe cases often require humane euthanasia.