BASICS
- A genetic neurologic disease due to neonatal apoptosis of cerebellar Purkinje cells
- The cerebellum processes peripheral proprioceptive input and coordinates the quality of motor activity through its efferent pathways; simplistically, it “tones down” somatic upper motor neurons in the brainstem
- Cerebellar abiotrophy may be an inherited metabolic defect of cortical cerebellar neurons in some breeds, particularly Arabians of Polish, Egyptian, and Spanish types
- The result is formation and then premature death of these neurons during late fetal or early postnatal life, resulting in a cerebellum that may be normal at birth and degenerates thereafter
- Gene mapping of affected Arabian foals has indicated an autosomal recessive single nucleotide polymorphism with variable expression that results in the downregulation of the gene MUTYH, involved in the repair of DNA
- Cerebellar abiotrophy occurs in lines of Arabian horses and has occasionally been noted in breeds descended from Arabian horses and Oldenburg, Gotland, and Eriskay foals
- Foals may be affected at birth, but often disease is not evident until a few weeks or months of age
- Foals appear normal at birth as these clinical syndromes, for the most part, are not congenital
- Affected animals also have a normal gait for a period postnatally, then demonstrate a syndrome related to progressive cerebellar degeneration
- Head tremor is a characteristic finding in affected horses. It manifests when the horse is heating or with other voluntary movements of the head (intention tremor)
- A basewide stance and hypermetric or hypometric ataxia may be prominent; some affected animals show hypometric gait at a walk, which becomes hypermetric at faster gaits
- There is no weakness. Intention tremor, an absent menace response with intact vision and pupillary light reflexes, is also evident
DIAGNOSIS
FOLLOW-UP
MISCELLANEOUS