ArtsAutosBooksBusinessEducationEntertainmentFamilyFashionFoodGamesGenderHealthHolidaysHomeHubPagesPersonal FinancePetsPoliticsReligionSportsTechnologyTravel

Horse Disease Focus - EPM

Updated on March 6, 2013

What is EPM?

EPM is Equine Protozoal Myeloencephalitis. It is an infectious disease that causes neurological and brain problems and can have permanent effects on a horse.


EPM can cause a wide variety of symptoms, depending on exactly what part of the brain or central nervous system is affected.

The most common symptoms are listed below:

1. Lack of coordination or balance, especially in the rear feet. This may show up more when walking or standing on a slope, or become obvious when a hoof is lifted. The horse may lean against the stall wall or a tree or fence for balance. Gaits may lose purity or impulsion. The horse may stumble or slip for no apparent reason.

2. Muscle atrophy might be observed over the rump and shoulders, sometimes dramatically affecting the fit of the saddle.

3. Soreness in the back or tail, including carrying the tail at an odd angle or to one side (note that I've seen horse's carry their tail to one side because of back soreness from other causes).

4. Standing oddly or not square, often with a hoof cocked to the side, or dragging a hoof when walking, especially on a circle.

5. Sweating in an unusual pattern, or sweating for no apparent reason.

6. A visible droop to the lip or one ear, or a facial twitch. Carrying the head tilted to one side.

7. 'Quidding' or dropping feed when there are no dental problems, or having difficulty swallowing.

8. Behavioral changes, that can include aggression.

Rarer symptoms are: A gelding 'dropping' when not urinating (bear in mind many geldings still have a fair bit of libido and will 'drop' when there is a mare in heat around or even when just 'happy'), extreme lethargy or diarrhea.

EPM symptoms may not appear for a long time after infection. The incubation period can be as long as two years.


The first line of attack is to kill the protozoa. This requires a drug regimen which kills or retards the reproduction of the disease-causing organism, S. neurons. This does not generally remove all of the threat, but rather weakens it to the point where the horse's immune system can beat it. Because of this, immune-boosting supplements are often also prescribed. The horse may also be given an anti-inflammatory to reduce symptoms and supplemented with vitamin E. Full rest is recommended.

EPM drugs are generally given orally once a day.

Some horses benefit from acupuncture and probiotics, but horses with an active EPM infection should not be given chiropractic treatment.

Once the infection is dealt with, the horse will need to be rehabilitated. This may take some time. Horses that continue to show stumbling and lack of coordination should not be ridden, for the safety of the rider. The horse may have permanent neurological problems and may never perform at the level it was at before. However, most horses make a reasonable recovery with a slow return to work, a training tune-up and possibly physical therapy. A horse that has had EPM should be treated the same as one that is extremely out of shape.

Horses may also have vision changes, jaw changes that require a change of bit, and may need extra support for a while when being shod or trimmed. While the horse recovers, only an experienced rider capable of supporting and balancing a horse should ride it.

Some horses may, unfortunately, not be ridable again.

Causes and Prevention

The way to prevent EPM is to prevent the infection with S. Neurons in the first place.

The most common host of S. Neurons is the opossum - for this reason, EPM infections are far more common in areas where opossums are plentiful. (Horses cannot infect other horses with EPM). Keep all hay and grain secure so that opossums cannot get to it. Do not leave the barn cat's food out at night if there are opossums in the area - it's far too much of a temptation for them. Lock up all food - horse, human and pet, and clean up any spilled grain. Empty the trash can frequently and consider investing in a wildlife-proof trash can if you have one outside the barn.

Horses in good general health and free of stress are less likely to catch any kind of disease, including EPM. Make sure your horse has a balanced diet with all the trace elements it needs.

There is currently no vaccine for EPM, but one is being actively researched.


    0 of 8192 characters used
    Post Comment

    No comments yet.


    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at:

    Show Details
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the or domains, for performance and efficiency reasons. (Privacy Policy)
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)