What is Cerebellar Abiotrophy?
This disease is sometimes referred to as Cerebellar Cortical Abiotrophy (CCA), and is caused by the destruction of the Purkinje cells (neurons) in the cerebellum of the brain. The problem is that the cells are not able to repair themselves and they are responsible for coordination and balance. Without these neurons, the horse is not able to judge distances, keep their balance, and they will have frequent falls. Because it is such a gradual disease in many cases, it is not always noticeable and may not be noticed until the neurons are mostly destroyed. Unfortunately, horses with CA are unable to be ridden because they are too uncoordinated. Also, those suffering with severe CA are dangers to themselves due to how accident prone they are.
Cerebellar abiotrophy (CA) in horses is a congenital disease of the brain that is debilitating and incurable. This neurological illness seems to mainly affect certain breeds of horses such as Arabians, Bashkir Curly horses, Trakehners, and Welsh ponies. However, other breeds such as Swedish Gotlands, Miniature horses, and Oldenburgs have been reported as having CA as well. In fact, CA has been recorded in all of the bloodlines. The signs of CA are head tremors, difficulty standing up, and trouble walking. A horse can actually carry this disease without having any of the side effects. Most of the horses with CA seem normal at birth, and the disease may not be evident for about four months. Although, there are some cases where the disease is evident at birth and some that are not noticed until the horse is over a year old.
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Symptoms of Cerebellar Abiotrophy in Horses
Symptoms of CA are usually noticed right after birth, but may be overlooked for months because it can resemble other conditions. Sometimes it is thought that the horse is getting injured falling down or that the shakiness is caused by an injury. The symptoms can vary in severity, with some horses showing severe walking and running inability and no balance and some that seem normal. However, if your horse has these symptoms, you should call your equine veterinarian right away.
- Lack of balance
- Exaggerated wide-legged stance
- Poor muscle control
- Head shaking
- Unable to get up from laying down
- Easily startled
- Frequent falls
- High stepping
- Abnormal gait
- Mild cases are rarely noticed until about 6 months of age
- Severe cases are so bad the horse may not even be able to sit up
Causes of Cerebellar Abiotrophy in Horses
Medical professionals found that CA is an inherited autosomal recessive disease, but they have been unable to find the exact cause. The loss of certain neurons has a major impact on balance and coordination. Any breed of horse up to a year old can suffer from CA, but there are certain breeds that are more susceptible, such as:
- Arabian foals
- Bashkir Curly horses
- Welsh ponies
- Swedish Gotland ponies
Diagnosis of Cerebellar Abiotrophy in Horses
If you believe your horse may have CA, it is important that you see a veterinarian that specializes in equine care. While the symptoms of CA are usually obvious to an equine veterinarian, it is impossible to get a definitive diagnosis until a post-mortem examination. The symptoms are similar to other injuries or illnesses such as wobbler's syndrome, head injury, cerebellar hypoplasia (CH), and equine protozoal myeloencephalitis (EPM), so the veterinarian will need to rule out anything else before a concrete diagnosis is confirmed. A physical examination will be done first, which includes blood pressure, weight, height, body temperature, breath sounds, body condition score, lameness and vision check. The veterinarian will have you walk your horse around to see how the muscles and joints are performing. There are also several neurological tests that the veterinarian can perform to see if the symptoms are consistent with CA.
Some equine veterinarians recommend doing a spinal tap to check for other neurological disorders. However, this is not common. There are also DNA tests that can check for the CA allele, but this will only confirm that your horse is a carrier. It does not necessarily confirm the diagnosis. In addition, laboratory tests will need to be performed to rule out other illnesses. Some of these tests are a chemistry profile to assess vital organ function and metabolism, complete blood count, and a blood urea nitrogen (BUN) to check levels of protein. Digital radiographs (x-rays), ultrasound, and maybe an MRI or CT scan may be needed as well.
Treatment of Cerebellar Abiotrophy in Horses
There is no cure for CA, but it does not have to be a death sentence for your equine companion. The disease will usually level out within the first two years of life. Your horse’s intelligence and most cognitive functions are usually normal so if your horse is only mildly affected, a regular lifespan is expected. Horse’s with severe cases of CA are usually not as lucky and need to be euthanized to prevent them from harming themselves or others.
Recovery of Cerebellar Abiotrophy in Horses
If your horse is able to function and take care of himself, all you will need to do is provide an accident safe zone to keep him from hurting himself. The veterinarian will give you instructions on what can be done and how fast the CA may progress. It is not recommended that you ride or work these horses in any way because of their inability to maintain balance.