Equine Protozoal Myeloencephalitis (EPM) in Horses
Symptoms of EPM in Horses
One of the difficulties with diagnosing EPM is that it can look like many other neurological diseases, particularly in the beginning. It is a progressive disease, meaning it tends to worsen over time. However, some horses progress through the illness faster than others, and it is not uncommon for a horse to develop worsening symptoms, then level off for awhile, sometimes even for months, before once again beginning to deteriorate.2
Symptoms can vary depending on whether the horse's brain or spinal cord is more heavily affected. But the following are common symptoms to watch for.
Symptoms
- Loss of coordination
- Muscle atrophy
- Difficulty swallowing
- Gait abnormalities
- Stumbling
- Behavioral changes
- Standing with feet splayed or leaning against a wall for support
- Weakness
- Drooping eyelid
- Head tilt
The symptoms of EPM can begin quite suddenly or slowly progress over time. As a general rule, the symptoms are asymmetrical, meaning they affect one side of the horse's body more than the other.2 So you might notice that your horse moves the legs on its left side in an uncoordinated fashion, but still moves them normally on the right. Commonly, the horse will seem to have poor balance and may stumble or move in an abnormal way. Its muscles might atrophy, leading to weakness and further inability to walk normally.
If the horse's spinal cord is most affected, which is the commonest presentation of EPM, you'll notice more difficulties with movement, balance, and coordination. If the horse's brain is more affected, symptoms can include paralysis in the facial muscles, making it difficult for the horse to swallow or move its tongue, as well as lethargy, behavioral changes, and drooping eyelid.1
