Cerebellar Abiotrophy
Learn what the condition is, how it may be detected early, how it is treated or managed, and which breeds or species are linked to it.
Condition snapshot
A concise guide to the condition’s pattern, detection, management and urgency.
Breeding advice appliesUse the screening guidance and veterinary or genetics advice before breeding an affected or at-risk animal.
This snapshot is a general guide, not a diagnosis or treatment plan. New, severe or worsening signs require veterinary assessment.
About the condition
Cerebellar abiotrophy is an inherited neurological disease in which Purkinje cells of the cerebellum degenerate after a foal is born. The cerebellum coordinates the rate, range and force of movement, so affected foals remain strong and alert but cannot accurately control motion. Disease is best recognised in Arabians and Arabian-related breeds and is associated with a recessive variant near the MUTYH gene.
Signs commonly appear from a few weeks to several months of age, though onset and severity vary. Foals develop intention tremor of the head, exaggerated high-stepping limb action, a wide-based stance, truncal sway, poor balance and absent or reduced menace response despite intact vision. They may startle easily, fall, collide with fences or flip over backwards. Signs can seem to worsen as activity increases and protection from the mare decreases, but the primary cell loss is generally non-progressive after its initial course.
The foal is not weak, painful or contagious. Cerebellar hypoplasia, neonatal hypoxia, trauma, cervical disease, EDM and infectious encephalitis can create overlapping incoordination. A missing menace response alone is not diagnostic because it normally develops after birth and can be delayed in young foals.
CA is autosomal recessive: two clinically normal carriers can produce an affected foal. Some mildly affected horses survive in carefully controlled environments, but unpredictable falls make handling and riding hazardous. There is no treatment that restores lost Purkinje cells. Prognosis is based on functional safety and welfare, while DNA testing makes affected births preventable without automatically excluding every healthy carrier from the breed.
Dysmetria reflects inaccurate scaling of movement rather than loss of strength: the foal may lift a leg excessively high and place it forcefully. Intention tremor becomes most obvious when reaching toward feed or investigating an object. Preserved vision with absent menace occurs because the cerebellar component of the learned blink response is impaired.
Screening & Early Detection
A neurological examination localises dysfunction to the cerebellum by identifying dysmetria, intention tremor, truncal sway and menace deficit without paresis or loss of conscious proprioception. Age at onset, breed, parentage and video of progression are recorded. Ophthalmic examination confirms that apparent menace loss is not blindness.
A validated DNA test classifies horses as clear, carrier or affected for the recognised Arabian-associated variant. Testing is useful in a symptomatic foal and before breeding, but results must match the breed and clinical picture. Routine blood work and cerebrospinal-fluid analysis help exclude metabolic, inflammatory or infectious disease; imaging is selected for trauma or structural malformation. Definitive pathological confirmation shows cerebellar Purkinje-cell loss after death.
Young foals are re-examined because menace response and coordination mature with age. Related horses are not declared affected from pedigree alone. Breeding records link genetic results to microchip or other permanent identification. A negative test excludes the tested variant, not every cause of cerebellar dysfunction in every breed.
The foal's strength and conscious limb placement remain important contrasts with spinal-cord disease.
Treatment & Management
No drug, supplement or exercise programme replaces destroyed Purkinje cells. Management for a mildly affected horse uses spacious uncluttered housing, highly visible safe fencing, level footing, low feed and water points and quiet companions. Sharp edges, narrow doorways, steep slopes, transport and situations that provoke abrupt movement are minimised. The horse is not ridden, driven or handled by inexperienced people.
Repeated assessment considers frequency of falls, injury, ability to eat, rise and interact, and risk to handlers. Sedatives may worsen coordination and are not a long-term solution. Vitamin E supplementation is appropriate only for documented dietary inadequacy and does not cure genetic CA. Humane euthanasia is the responsible option when falls or distress cannot be prevented.
Control is genetic. Clear-to-clear and carrier-to-clear matings cannot produce an affected foal from the tested variant; two carriers are not paired. Healthy carriers need no clinical therapy and can be retained with planned testing to protect genetic diversity. Foals from carrier matings are tested before breeding or sale, and results accompany identity records. If an affected foal is born, both parents and related breeding stock are tested rather than assuming colour, pedigree name or normal movement reliably identifies carrier status.
