Is It Cerebellar Hypoplasia or Cerebellar Abiotrophy?

If you thought the science behind cerebellar hypoplasia was complicated, just wait.

Photo courtesy Erik Nygren

I recently read about another condition that is so similar to CH that it is often confused for cerebellar hypoplasia. Consequently, there are times that vets sometimes diagnose this condition as CH, when it’s really not.

It’s called cerebellar abiotrophy.

It’s a disease that’s found in horses and dogs, much like CH, but it can also occur in cats, cattle and sheep, too. The condition’s symptoms are similar to CH, but the important difference is what causes this condition and when.

As you may know, cerebellar hypoplasia is a congenital condition resulting in the underdevelopment of the cerebellum, which is caused by the feline distemper virus or trauma while in utero. By and large CH occurs before a kitten is born, although there have been known to be a few exceptions.

Meanwhile, cerebellar abiotrophy is another type of cerebellar degeneration that occurs after the animal is born.

Cerebellar abiotrophy occurs when there is a loss of Purkinje cells in the cerebellum. These Purkinje cells, which affect balance and coordination, die off.

These cells are important because these cells allow the cerebellum’s different layers of the brain to communicate with one another. When they die off, that communication stops, and the animal can lose its sense of space and distance, as well as impacting its balance and coordination. 

From what I’ve read, it’s not entirely clear what causes this condition, but it’s thought to be caused by an “intrinsic metabolic defect.”

Photo courtesy Zillafag

If an animal has this defect, his Purkinje cells usually start to die off right after birth. The condition is usually noticeable before the animal is six-months old, although sometimes the cells die off more gradually, and an animal can be much older before the condition’s characteristics are noticeable.

Some of its symptoms include: ataxia, a wide-leg stance, and head tremors, which sounds a great deal like CH. But there are other symptoms that are more specific to CA, such as: hyperreactivity, lack of menace reflex, a stiff or high-stepping gait, jerky head-bob movements while in motion, poor depth perception, and a general inability to determine space and distance.

It sounds like the symptoms may worsen as the disease progresses, but some say it can stabilize over time. Like with CH, some animals with CA may actually learn to compensate and improve over time. Similarly, like CH, CA does not impact intelligence, and most animals can live out a normal lifespan.