Cerebellar Abiotrophy - Symptoms

Symptoms

Symptoms of cerebellar abiotrophy include ataxia or lack of balance, an awkward wide-legged stance, a head tremor (intention tremor) (in dogs, body tremors also occur), hyperreactivity, lack of menace reflex, stiff or high-stepping gait, coarse or jerky head bob when in motion (or in very young animals, when attempting to nurse), apparent lack of awareness of where the feet are (sometimes standing or trying to walk with a foot knuckled over), poor depth perception, and a general inability to determine space and distance. The symptoms are, when taken as a group, fairly unique and not easily mimicked by other illnesses, though certain types of neurological injury and infection do need to be ruled out. Verifying the diagnosis in a laboratory setting is only possible by examining the brain post-mortem to determine if there has been a loss of Purkinje cells.

Most affected animals have normal intelligence and mildly affected animals can, in theory, live out a normal lifespan. However, affected animals are quite accident-prone, and for this reason many animals that develop CA, particularly horses, are euthanized for humane reasons. Horses may experience difficulty stepping up and over objects, run into fences, fall easily, and even if allowed to mature to full growth, are generally considered unsafe to ride. Dogs may need lifetime assistance with tasks such as climbing stairs.

In horses, the symptoms may worsen from the time of onset for six to 12 months, but if not severe enough to mandate euthansia, they stabilize over time. In some dog breeds, symptoms appear to progressively worsen, but research is not consistent on this point. There also is some evidence that affected animals partially compensate for the condition by cognitively learning alternative methods for moving or to determine distance, and thus appear to improve because they become less accident-prone.