Cerebellar Abiotrophy in Horses: Genetic Incoordination in Young Horses

Quick Answer
  • Cerebellar abiotrophy (CA) is an inherited neurologic disease that affects coordination, most often in Arabian and Arabian-influenced foals.
  • Foals are usually normal at birth, then develop signs such as head tremors, exaggerated gait, wide-based stance, and startling easily within the first weeks to months of life.
  • There is no curative treatment. Care focuses on safety, confirming the diagnosis, and making a realistic quality-of-life plan with your vet.
  • A DNA test can identify affected horses and carriers, which is especially helpful for breeding decisions and prevention in at-risk bloodlines.
Estimated cost: $300–$2,500

What Is Cerebellar Abiotrophy in Horses?

Cerebellar abiotrophy, often shortened to CA, is a genetic neurologic condition that affects the cerebellum, the part of the brain that helps control balance, coordination, and precise movement. In affected foals, the cerebellum develops, but certain neurons then begin to die off too early. That leads to incoordination rather than weakness.

Most foals with CA look normal at birth. Signs often become noticeable around 6 weeks of age, though they may appear later, sometimes up to 4 to 6 months. Pet parents may first notice a fine head tremor when the foal reaches for milk or feed, an exaggerated front-leg action, or a foal that seems unusually clumsy and easily startled.

CA is seen most often in Arabian horses and horses with Arabian ancestry, though the mutation has also been identified in some related or Arabian-influenced breeds. Because affected horses can fall or injure themselves, this is not a condition to monitor casually at home. Your vet should evaluate any young horse with new balance or coordination problems.

Symptoms of Cerebellar Abiotrophy in Horses

  • Head tremor, especially during goal-directed movement
  • Ataxia or unsteady coordination
  • Exaggerated action of the forelegs
  • Wide-based stance
  • Startling easily or overreacting to stimuli
  • Frequent stumbling or falling
  • Difficulty rising from a reclining position
  • Normal strength but poor precision of movement

See your vet promptly if a foal shows head tremors, repeated stumbling, exaggerated gait, or unusual balance problems. See your vet immediately if the horse is falling, unable to rise, injuring itself, or unsafe to handle. These signs can overlap with other neurologic problems, including trauma, infection, toxin exposure, or other inherited disorders, so an exam matters.

What Causes Cerebellar Abiotrophy in Horses?

CA is caused by an inherited genetic mutation and follows an autosomal recessive pattern. That means a foal must inherit one copy of the mutation from each parent to be affected. Horses with only one copy are typically carriers and usually do not show signs, but they can pass the mutation to offspring.

When two carriers are bred, each foal has a 25% chance of being affected, a 50% chance of being a carrier, and a 25% chance of inheriting no copies of the mutation. This is why apparently healthy breeding horses can still produce an affected foal.

The condition is found primarily in Arabians, but the mutation has also been reported in some breeds with Arabian foundation stock, including Danish Sport Horses, Trakehners, Welsh Ponies, and other Arabian-influenced lines. CA is not caused by poor care, feeding mistakes, or an injury after birth. It is a hereditary disorder, so prevention centers on informed breeding decisions.

How Is Cerebellar Abiotrophy in Horses Diagnosed?

Diagnosis starts with a full history and neurologic exam by your vet. The exam may show classic cerebellar signs such as intention head tremor, exaggerated limb action, a wide-based stance, normal strength with poor coordination, and an exaggerated startle response. Because several neurologic diseases can look similar early on, your vet may recommend testing to rule out other causes.

Depending on the horse's age, signs, and region, the workup may include a physical exam, bloodwork, and testing for other neurologic conditions. In some cases, referral to an equine hospital is helpful if the diagnosis is unclear or if the horse is unsafe to manage on the farm.

A DNA test is one of the most useful tools when CA is suspected in an at-risk horse or bloodline. UC Davis offers a CA test using 20 to 40 hairs with roots, and the reported test cost is about $45 for a single CA test or about $85 for the Arabian health panel. Genetic results can identify horses as normal, carrier, or affected, which helps confirm suspicion and guide breeding decisions.

Your vet may also discuss the difference between cerebellar abiotrophy and cerebellar hypoplasia. In hypoplasia, the cerebellum does not develop normally before birth. In abiotrophy, development occurs first, then neurons degenerate later, so foals may seem normal initially and then become abnormal over time.

Treatment Options for Cerebellar Abiotrophy in Horses

Spectrum of Care means you have options. Here are treatment tiers at different price points.

Budget-Conscious Care

$300–$900
Best for: Foals with mild to moderate signs when the main goals are confirming likely CA, reducing injury risk, and making a practical home-care plan.
  • Farm-call exam and neurologic assessment
  • Basic bloodwork or limited rule-out testing if needed
  • CA genetic test submission
  • Turnout restriction or small, hazard-reduced enclosure
  • Environmental safety changes such as soft footing, lower-stress handling, and separation from aggressive herd mates
  • Quality-of-life monitoring with your vet
Expected outcome: Guarded for long-term safety and athletic function. Horses with confirmed CA are not considered safe for riding or driving, and some can only be managed as pasture companions if signs remain mild.
Consider: This approach keeps costs lower, but it may leave some diagnostic uncertainty if other neurologic diseases have not been fully ruled out. It also does not change the underlying disease.
Most Common

Recommended Standard Treatment

$900–$2,500
Best for: Most suspected cases, especially young Arabians or Arabian-cross foals with classic signs where the family needs a clearer diagnosis and a realistic care plan.
  • Comprehensive exam by your vet
  • Full neurologic workup and targeted rule-out testing for other causes of ataxia
  • CA genetic testing
  • Short-term supportive care and handling recommendations
  • Written safety plan for housing, transport, and daily management
  • Breeding counseling for related horses and parents when appropriate
Expected outcome: Guarded to poor for future performance use, but clearer diagnosis helps families make safer and more informed decisions. Some mildly affected horses may live as non-ridden companions if they can be kept safe.
Consider: Higher upfront cost than conservative care. Even with a complete workup, there is still no curative treatment, so the value is in clarity, safety, and planning rather than recovery.

Advanced / Critical Care

$2,500–$6,000
Best for: Complex or atypical cases, horses with severe signs, or situations where your vet needs to rule out other serious neurologic diseases before making major decisions.
  • Referral-hospital neurologic consultation
  • Advanced imaging or specialized diagnostics when another brain or spinal condition is still possible
  • Hospitalization for severe safety concerns or inability to rise
  • Necropsy planning if diagnosis remains uncertain after death
  • Humane euthanasia and aftercare planning when quality of life or safety is poor
Expected outcome: Poor for return to normal athletic function. Advanced care may improve diagnostic certainty, but it does not reverse CA.
Consider: This tier can add significant cost and stress. It is most helpful when the diagnosis is unclear, the horse is severely affected, or breeding-program decisions depend on maximum certainty.

Cost estimates as of 2026-03. Actual costs vary by location, clinic, and individual case.

Questions to Ask Your Vet About Cerebellar Abiotrophy in Horses

Bring these questions to your vet appointment to get the most out of your visit.

  1. Do my horse's signs fit cerebellar abiotrophy, or are there other neurologic diseases we need to rule out first?
  2. What parts of the neurologic exam point toward a cerebellar problem rather than weakness or lameness?
  3. Should we run a CA genetic test, and which horses in this family line should also be tested?
  4. Is my horse safe to handle, trailer, turn out, or keep with other horses right now?
  5. What housing or footing changes would lower the risk of falls and injuries?
  6. Based on my horse's current signs, is pasture-only management realistic, or is quality of life already a concern?
  7. If this horse is confirmed affected or a carrier, what breeding recommendations do you suggest for related horses?
  8. What signs would mean we should recheck immediately or discuss humane euthanasia?

How to Prevent Cerebellar Abiotrophy in Horses

Because CA is an inherited disorder, prevention is mainly about breeding management, not vaccines, supplements, or training changes. The most effective step is genetic testing before breeding in horses with Arabian ancestry or bloodlines known to carry the mutation.

A horse that is a carrier is usually healthy, but breeding two carriers together can produce an affected foal. Testing allows breeders and pet parents to make informed mating choices and avoid carrier-to-carrier pairings. That can reduce the risk of producing affected foals while still allowing thoughtful breeding decisions.

If you are buying a young Arabian or planning a breeding, ask about parental genetic status and whether CA testing has already been done. If a foal develops suspicious neurologic signs, keep handling conservative and involve your vet early. Early recognition cannot prevent the disease in that foal, but it can help prevent injuries and guide safer decisions for the horse and the breeding program.

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