Equine Diseases

Equine Diseases - Atypical Myoglobinuria

Description of Atypical Myoglobinuria:

Atypical myoglobinuria is a serious equine muscle disorder. Atypical means it does not behave as expected. Myoglobinuria means that there is muscle damage, the end products of which are passed out in the urine. Atypical myoglobinuria can occur in little worked horses. It usually affects several horses or ponies in a group kept at grass with little or no supplementary feeding. Outbreaks of Atypical Myoglobinuria tend to appear after a period of heavy rain, when the animals may have become cold and wet. Their temperature, respiratory rates and pulse tend to remain normal. It is particularly upsetting as it often affects a group of horses often leading the owner to think the animals have been poisoned. Fortunately, the condition is fairly rare.

Causes of Atypical Myoglobinuria:

Associated with a sudden deterioration in weather conditions

Thought to be connected with a toxic fungal overgrowth that flourishes in foul weather.

Not protecting susceptible horses by providing shelter from bad weather

Not ensuring horses have supplementary feed, such as plenty of hay, while out at grass.

Not ensuring general good health and well-being

Not worming or taking care of infestation

Symptoms of Atypical Myoglobinuria:

Mainly suffered in a Spring or Autumn associated with bad weather, the main symptoms are:

• Sudden onset of stiffness unrelated to exercise
• Horses appear very weak and tend to collapse easily, indicating muscle weakness, but affected muscle groups are not swollen or painful
• The horses do not seem to be in severe pain and are usually able to eat and drink normally, even if they are too weak to stand up
• The horse's urine is an abnormally dark red to chocolate brown colour

Treatment of Atypical Myoglobinuria:

There is no miracle cure. A blood test should be obtained to ascertain the condition of muscle enzymes. If these are very high, it will confirm the existence of Atypical Myoglobinuria . The horse may be put on supportive treatment administered via a drip or painkillers.