What Is White Muscle Disease In Horses?

Last Updated on August 18, 2022

Many equine enthusiasts may have never come across white muscle disease in horses, but it is important to understand the mechanism behind this complex medical disorder. Let’s find out everything you need to know about white muscle disease in horses!

What Is White Muscle Disease In Horses?

White muscle disease, more correctly known as nutritional myodgeneration (NMD), is a disorder that is most common in newborn foals. NMD normally occurs when the foal does not receive enough selenium from its mother.

As the broodmare grazes, the grass she eats contains a wide range of vitamins and minerals, one of which is selenium. As the foal receives all of its nutrition from the dam both before and after birth, it is completely reliant on the mother to provide all the nutrition it needs.

Unfortunately, in large areas of the US, grazing land does not contain sufficient levels of selenium. Plants and grasses take up selenium through their roots, from the groundwater and soil. If the dam cannot get enough selenium in her diet, she cannot then provide her foal with enough selenium.

Click Here to Get Info About:

What Are The Signs Of White Muscle Disease In Horses?

Selenium is vital for newborn foals as it is an essential trace mineral that provides important antioxidant functions. When a foal is deficient in selenium, the main body system affected is the muscular system. These foals also often have a rapid, irregular heartbeat.

Muscle cells will start to degenerate, and skeletal muscle turns paler in color – this is where the name ‘white muscle disease’ comes from. These foals are normally weak at birth, and show signs of stiffness due to myopathy of the muscles. They can show clinical signs such as trembling and difficulty standing.

Foals with white muscle disease exhibit a classic set of symptoms, including difficult swallowing and respiratory distress. This puts them at increased risk of aspiration pneumonia, as they are unable to nurse from the dam correctly. The breathing difficulties can lead to respiratory failure and death.

How Is White Muscle Disease In Horses Diagnosed?

Diagnosis of white muscle disease in horses is relatively simple. Your veterinarian will take a blood sample, and check levels of selenium and vitamin E – if these are low, then NMD is highly likely. They will also test the muscle enzymes in the blood, which will indicate the severity of the disease and the extent of the muscular damage.

If a foal dies unexpectedly or during treatment for NMD, a post-mortem examination will show skeletal muscle that is pale or even completely white in color.

Horse Health Vita E & Selenium Crumbles Horse Vitamin Supplement

How Is White Muscle Disease In Horses Treated?

When a foal is diagnosed with white muscle disease, your veterinarian will normally immediately start a course of intramuscular selenium injections. If vitamin E levels were shown to be low on the blood tests, an oral vitamin E supplement will also be given.

It can take time to restore the levels of selenium and vitamin E to their correct levels, so it is normally necessary to give the foal supportive treatment at the same time. This will normally include monitoring and regulating the foal’s fluid balance, by administering intravenous fluids or oral electrolytes. If the foal has respiratory problems or secondary aspiration pneumonia, antibiotics will commonly be administered.

Foals with white muscle disease are often weak and unable to stand for long periods. In this situation, it is normally preferable to hospitalize the foal in a specialist equine veterinary clinic so the appropriate care can be provided.

The foal will need to be provided with a deep soft bed that is kept clean and dry at all times. It will also be necessary to assist the foal to stand and turn it over at regular intervals to prevent the development of ulcers and skin sores.

A foal that is unable to nurse properly due to weakness or difficulty swallowing may need to be fed from a bottle or via a nasogastric tube. The dam should be kept nearby to help maintain the bond between mare and foal.

Foals that receive a prompt diagnosis and swift treatment for white muscle disease normally make a full recovery. If the disease has progressed to the point where the cardiac muscle is affected, the prognosis is much poorer and the foal may not survive.

How Is White Muscle Disease In Horses Treated

Summary – White Muscle Disease In Horses

So, as we have learned, white muscle diseases in horses occur mainly in newborn foals when they do not receive enough selenium from their mother. Foals with white muscle disease have symptoms including difficulty swallowing and respiratory distress, putting them at increased risk of aspiration pneumonia. A blood test can be used to diagnose white muscle disease in foals, and treatment includes selenium injections and supportive therapies such as intravenous fluids and electrolytes.

We’d love to hear your thoughts on white muscle disease in horses! Have you ever had a horse diagnosed with this complex medical condition? Or maybe you’ve got some questions about the best way to prevent white muscle disease in your foal? Leave a comment below and we’ll get back to you!


What are the symptoms of white muscle disease?

White muscle disease affects both the skeletal and cardiac muscle of newborn foals. Foals with this disorder will exhibit symptoms including respiratory distress and difficulty drinking.

Is white muscle disease reversible?

White muscle disease in foals is reversible if treatment is started quickly. If the condition is left to develop then the likelihood of a full recovery becomes less likely. Once the cardiac muscle around the heart becomes compromised it is highly unlikely that the foal will recover.

Is there a cure for white muscle disease?

White muscle disease in foals can be treated with a combination of selenium injections, vitamin E supplementation, and supportive therapies. Foals with this disease can be wobbly and weak, and may need assistance to stand and nurse. Oral or intravenous fluids may be required for foals that are not able to drink normally.

Why is it called white muscle disease?

Nutritional myodgeneration (NMD) is commonly referred to as white muscle disease as it causes deterioration of the cells within muscular tissue. This causes the muscles to become paler in color, and in severe cases they can be completely white.