Uncontrolled legs that stumble or even break down: horses that suffer from ataxia have a lack of control over their legs. In general there are three different types of ataxia: spinal, cerebral and cerebellar Ataxia.
Everyone who once saw a horse with Ataxia understands the name of this disease: the Greek word ataxia stands for “lack of order” – and that is exactly how the movements of the horse can be described. The hind legs hit in several directions and the entire body movement of the horse appears chaotic and arbitrary.
What is Ataxia?
Ataxia is a dysfunction of the central nervous system that is the spinal cord and the brain. This dysfunction can have many different origins. The vertebral column is made out of the spinal canal and the spinal cord (inside of the spinal canal). The nerves of the spinal cord are the “information channels” of the whole organism: The commands of the brain get transported by these nerve fibers so that they can reach the respective part of the body. In case of an Ataxia this communication between the brain and the rest of the body is disturbed. The horse loses his feeling for his hoof and is not able to place it to the front, back or side. Instead he only realizes that his hoof already is on the ground when he feels the pressure coming up his leg. If you watch a horse with Ataxia you can clearly see how it has great problems to coordinate his movements.
The three different types of Ataxia
Ataxia can be categorized into three different types: the spinal, the cerebral and the cerebellar Ataxia.
Most of the horses suffer from the spinal Ataxia. In this form of the disease there is a constriction of the horses´ spinal canal. Certain vertebras press on the nerves that are inside the spinal canal (mostly in the area of the cervical vertebrae). This dysfunction in the “information channel” leads to a problem in the communication system: The transmission of the commands of the brain does not work correctly so that the muscles do senseless and disturbing moves. Horses that suffer from a spinal Ataxia are often called Wobbler.
Origins of a spinal Ataxia
In most cases horses get a constriction of the spinal canal after they fell down or tumbled. Especially young horses and stallions love to show impressive posing and wrangling on the pasture. There they can easily fall down or roll over their head and neck. Stones and branches hurt the horses´ back and cause swellings, inflammations or even joint dislocations. These swellings lead to the constriction in the spinal canal and an irritation of the nerve fibers in the spinal cord.
Additionally a spinal Ataxia can be the result of wrong feeding during the growth process of young horses (up to four years) and foals. A too high dose of phosphates and proteins cause an irregular growth process of the vertebral corpus. Certain vertebras in the area of the cervical vertebrae can easily crick and press on the spinal cord. This pressure increases if the horse lowers his head.
Cerebral and cerebellar Ataxia
In case of a cerebral and cerebellar Ataxia the horses´ brain is affected. Therefore the disturbance of the communication line is not at the channel (spinal cord) but directly at the sending point of the commands (brain). The cerebral Ataxia refers to all disturbances of the cerebrum,midbrain and interbrain. In opposite to this the cerebellar Ataxia describes the problems related to the little brain. This part of the brain is responsible for the transmission of the commands referring to the body balance and the sensory impressions.
Origins of a cerebral and cerebellar Ataxia
In most cases the damage of the brain is caused by viral and bacterial infections (this can be compared with the so called meningitis of humans). The most dangerous origin also is the most often one: Equine Herpes Virus. The virus causes swellings and inflammations in the brain and this leads to a bruise of the nerve fibers. The commands of the brain cannot get transmitted via the spinal cord to the muscles: The horse is nearly paralyzed! An infection with the dangerous borrelia burgdorferi bacteria has the same effects. They can cause an Equine Borreliosis what means dangerous inflammations in the brain. Further potential origins are a parasite infestation (they can spread from the brain into the entire spinal cord) as well as very dangerous intoxications (toxic substances especially attack nerve fibers.)
Symptoms of an Ataxia
The symptoms of an Ataxia are very diverse and depend on the respective degree of the disease. The symptoms come slowly and insidious so that the disease normally gets diagnosed very late. The first hint for an Ataxia is a staggering walk (some people say that the horse looks drunk). Especially the movements of the hind legs seem uncontrolled and without any order or system. The lack of balance can also be explained with the limited mobility of the neck: Due to the fact that the horse feels great pain as soon as he lowers his head the neck can hardly fulfill its balancing functions for the body. Moreover the horse can hardly go backwards: The immense bend of the neck increases the pressure on the spinal cord. The movement becomes even more painful when the horse tries to make tight turns. During this exercise one can easily see the lack of coordination: If you turn the horse several times around in a circle and then suddenly stop you will see how the hind legs continue to turn (they simply follow the gravitation). Then the horse needs some time until he finally is able to correct the position of his legs.
Further symptoms for an Ataxia:
- The horse stumbles very often
- The walk of the horse is very irregular and the horse has great problems to walk on an uneven ground (especially downhill)
- The hind legs are out of control and even break down
- You can easily pull the tail in one direction without feeling any resistance
Regularly experts and vets warn horse owners not to diagnose Ataxia as soon as their horses walk in an irregular way. There are many possible origins for a limping horse: a simple sprain or even a laminitis. However it is crucial that horse owners contact a vet as soon as they first notice a stumbling walk.
A cerebral or a cerebellar Ataxia is always introduced by an infectious disease. In case of an inflammation of the brain the horse just lies on the ground and is not able to move. The horse is in a life-threatening situation and needs immediate help and medicine. Due to the gravity of this disease many nerve fibers get damaged. If the horse is able to survive this infectious disease an Ataxia can be a possible sequela.
Diagnosis of Ataxia
As soon as the horse owner notices an irregular walk of the horse he must contact a vet. The owner can help to prepare the examination considering the following questions before the arrival of the vet:
- When did I see the first symptoms?
- What kind of symptoms did I see?
- Did my horse have an infectious disease/fever in advance?
- When was the last vaccination of my horse?
After the general examination of the horse the vet will examine the neurologic reactions of the horse. This means that the horse has to move in tight turns and backwards and the vet concentrates on the coordination of the legs. After some further tests the vet is able to give a diagnosis and only in some cases it is necessary to make an additional X-ray examination. If your horse is very difficult to examine the vet needs to transport him to the veterinary clinic for a surgery under general anesthetic. The horse gets an injection with a contrast medium so that the vet is able to localize the constrictions and sprains.
Therapy and possible cure
In general there are different degrees of Ataxia. Horses that suffer only from a light degree of Ataxia can easily live without any essential limitations (riders can even continue to ride them). If the horse however shows a great lack of coordination and moves in an unpredictable way or even breaks down with his hind legs it is an immense risk for the rider to keep on riding the animal. Generally it is very difficult to give a precise statement about the possible cure of the horse. Vets avoid any exact answer and try to stay very realistic – especially because they do not want to deceive the horse owners’ hopes. Riders need to be aware of the fact that a damage of nerve fibers never is curable.
In case of a spinal Ataxia vet and horse owner can work out an individual therapy program. The medicinal therapy is based on anti-inflammatory medicine like antibiotics,antiserums and possibly antiparasitics. Moreover it can be very helpful to feed additional Selenium and vitamin E. These two elements support the neck muscles and therefore help to relieve the cervical vertebrae. In case of a surgery the vertebras get stiffen so that they cannot press on the nerve fibers anymore. This surgery is very painful and limits the general mobility of the horse – and no one is able to guarantee that the horse will be able to control his legs afterwards. All these doubts already lead to many discussions about this surgery. The horse owner should try to find the best way for the horse – and should not forget that horses are powerful animals that love to move and run.