Last Updated on December 26, 2022
There is a lot more to owning a horse than what meets the eye. Horse owners must know how to properly care and feed their horse and also become familiar with what behavioral changes are considered normal to be able to detect signs of neurological problems in horses or when a veterinarian should be called out for an examination.
Many times when a horse shows signs of a simple ailment such as a lack of coordination, stumbling when being ridden, or tripping a few times while out on the trail many horse owners won’t give it a second thought, but should.
Neurological Disorders – Is this Behavior Common?
Neurological disorders are more common in horses than one would think. Many neurological disorders are hard to diagnose. They have similar symptoms or mimic symptoms of another bacterial or viral disease. When a horse begins to show abnormal behavior, signs of lameness, muscle weakness, lack of coordination, paralysis, fever, abnormal head carriage, a change in appetite, sudden weight loss, along with others should cause some concern and a call to the veterinarian is highly recommended.
Evaluation of Possible Neurological Disorder
A physical examination of your horse from a veterinarian is essential when trying to determine if a neurological disorder is present. Taking your horse’s temperature and evaluating the horse’s limbs can be helpful for the diagnosis. A horse’s temperature will fluctuate differently with a bacterial infection, than a viral one, as goes the same for neurological disorders. A horse’s gait may show abnormalities that are common with neurological issues and show up differently than those associated with soreness from hard work or injury. The information being gathered is very helpful in properly diagnosing your horse.
Most Common Neurological Diseases in Horses
Taking the time to become familiar with the most common neurological disorders will alert you to any changes that may need veterinary attention. It’s very common for diseases to affect a horse’s central nervous system. The most common disorders are Cervical Vertebral Stenotic Myelopathy (CSM). The four most common are Equine Protozoal Myeloencephalitis (EPM), Equine Motor Neuron Disease (EMND), and Equine Herpesvirus-1 Myeloencephalopathy (EHM).
Common Neurological Disorders Explained
CSM – also called wobbler syndrome, is compression of the spinal cord. CSM primarily affects young horses three months to a year old. This is a multifactorial disease where the cervical vertebrae have bony growth malformations and narrowing of the vertebral canal. If CSM occurs in older horses it is generally secondary to osteoarthritis in the spine. Surgery is currently the most effective option for treatment.
EPM – Horses that are under the age of five and over the age of thirteen have a higher risk of becoming infected with EPM. Sarcocystis neurona is the most common cause of EPM. It creates motor neuron damage and muscle atrophy. Horses become infected if they accidentally ingested Opossum feces during feeding or by consuming contaminated feed. EPM is treatable if diagnosed early on, otherwise, the only definitive test for EPM is with a post-mortem examination.
EMND – This disease affects the nerves supplying all muscles. Horses suffering from a Vitamin E deficiency for a minimum of 18 months will need to be evaluated by a veterinarian. The affected horses must take Vitamin E Supplements to slow the advancement of the disease. There is no treatment for EMND but with a proper diet and regular blood test to assess vitamin E levels you can slow the progression of the disease.
EHM – This virus has the ability to replicate rapidly creating a higher frequency of neurologic disease. It damages the blood vessels of the nervous system and causes “stroke-like” episodes. EHM is a part of the equine herpes virus, initially appearing in a viral stage and advancing into the respiratory tract and peripheral blood mononuclear cells. EPH is highly uncommon but is very serious if contracted.
Currently, there is no vaccine available, and is highly contagious between horses. Isolation outbreaks and a quarantine period is advised if horses are frequently in common areas.
Other neurological diseases to become familiar with would be Lyme Disease, Rabies, West Nile Virus, Botulism, and Tetanus. These diseases are also common among humans and currently, Rabies is the only one that is transmittable between humans and horses and vise versa.
Neurological diseases need to be addressed as soon as possible. In many cases the longer the disease goes untreated, the risk of death increases significantly. Symptoms that occur with these diseases have multiple signs of a disorder, only in rare instances has only one symptom at the time of diagnosis. Taking the horse’s history and breed into account can also be very helpful when beginning to diagnose.
What is EPM in a horse?
EPM or equine protozoal myeloencephalitis is a neurologic disease that horses get from eating infected opossum feces. Keep your horses healthy by storing grain in sealed bins and controlling opossum populations around your barn.
Symptoms include incoordination, loss of balance, loss of muscle mass, and decreased sensitivity to pain. Horses may show signs of depression, fatigue, and excessive sweating. They may also have a fever and be inappetent. Treatment involves supportive care, such as fluid therapy, IV fluids, and rest. Horses with EPM may require long-term care. Whereas most neurologic diseases in horses are not contagious to humans, EPM can be transmitted to humans through contaminated water or by handling an ill horse.
How quickly does EPM progress?
The onset of EPM is usually gradual, and if treatment is initiated early enough, signs may be minimal and difficult to detect. In horses with EPM, the clinical signs are mainly the result of inflammation and edema of the cerebellum and brainstem. Some of the clinical signs seen with EPM are similar to those seen with other types of central nervous system (CNS) disease, including paresis, paralysis, ataxia, recumbency, head pressing, circling, staggering, opisthotonos, and seizures. If not treated properly, these signs can become severe or even fatal. Affected horses should be isolated from other horses and from possible vectors, such as flies. Isolation includes a separate box stall, separate pen from other horses, separate pasture, and, in some cases, separate building. The isolation period is usually 2-3 weeks, but it may take longer, depending on the severity of clinical signs.
Can a horse recover from EPM without treatment?
Yes, some do. Most affected horses require long-term treatment (a minimum of six months) with steroids and/or antibiotics to control the inflammation. A Horse that recovers from EPM can return to its intended use.
An equine protozoal myeloencephalitis (EPM) survivor will likely need additional veterinary care and rehabilitation after the disease is treated. A horse with EPM will be at increased risk for laminitis, which can be fatal.
Can worms cause neurological problems in horses?
Absolutely! There have been many reported cases of neurologic problems associated with Setaria digitata infection in horses. The parasite can also affect the brain and spinal cord, causing severe inflammation and damage to nerve cells.
In horses, the most common signs of Setaria digitata infection are lameness, drooping ears, head shaking, and loss of coordination. Other signs include depression, weight loss, fever, and muscle tremors. The parasite is usually diagnosed by observing the larvae in the feces. A veterinarian can identify the presence of the parasite by performing a fecal examination.
What is the most common neurological condition in horses?
Certainly, cervical vertebral stenotic myelopathy (CSM) is the most prevalent. What is CSM? It is a disease that affects the spinal cord and nerve roots at the base of the neck. The condition is caused by compression of the spinal cord by the bony vertebrae of the neck. Symptoms include loss of coordination, stiffness, muscle weakness, and difficulty walking. How does CSM affect a horse? When the spinal cord becomes compressed, it may not have enough room to carry information to and from the brain. The horse can no longer walk properly and may fall down. CSM is the most common cause of paralysis in horses. Horses with CSM are usually given pain medication and rest. Sometimes, they are given corticosteroids.
Michael Dehaan is a passionate horse owner, horse rider, and lover of all things equine. He has been around horses since he was a child, and has grown to become an expert in the field. He has owned and ridden a variety of horses of different breeds, and has trained many to compete in shows and competitions. He is an experienced horseman, having worked with and competed many horses, including his own. He is an active member of the equestrian community, participating in events and teaching riding lessons.