CLOSTRIDIAL MYONECROSIS IN HORSES

« Back

Sep 28th, 18
Clostridial myonecrosis is a rapidly progressive necrosis of muscle. Clostridial refers to bacteria from the genus Clostridium. Myonecrosis refers to death of living muscle tissue.

CLOSTRIDIAL MYONECROSIS IN HORSES

Clostridial myonecrosis is a rapidly progressive necrosis of muscle. Clostridial refers to bacteria from the genus Clostridium. Myonecrosis refers to death of living muscle tissue. 

Clostridia are gram-positive, spore forming, anaerobic bacteria that are commonly found in the environment.  

The most commonly involved organism in cases of clostridium myonecrosis is C. perfringens, however a variety of clostridia can cause myonecrosis to include C. septicum, C. sporogenes, and C. sordellii. 

Other terms used to describe intramuscular colonization and infection with Clostridium spp. are termed clostridial myositis, clostridial cellulitis, malignant edema, or gas gangrene.


PATHOGENSIS OF DISEASE:

External Inoculation of spores: Clostridia spores may be deposited or inoculated into the horse’s muscle.

This can happen with an intramuscular injection with an irritating medication or a deep laceration that affects the muscle belly.

Most of the time, wounds/intramuscular injections do not result in clostridial myonecrosis due to the tissue remaining well oxygenated so the spores cannot grow.

However, if the muscle is damaged or inflamed and the blood supply and oxygen becomes very low the risk of clostridial myonecrosis increases significantly.


Growth of "resident spores":

It has been documented in the literature that some healthy horses have clostridia spores present in their muscle.

These particular spores normally do not cause any problems and cannot grow as long as the tissue/muscle is well oxygenated.

If for some reason the oxygen supply changes to the muscle for example after intramuscular injection with an irritating substance such as banamine, the spores can start to grow and traumatize the tissue.


What drugs are at higher risk of causing this?

Clostridial myonecrosis is most often seen in horses following an intramuscular injection with Banamine (Flunixine Meglumine).  

Other substances that have been associated with clostridial myonecrosis following intramuscular injections are: ivermectin, antihistamines, dipyrone, B vitamins, and phenylbutazone.

Intravenous injections DO NOT cause clostridial myonecrosis if they are done properly and the medication does not leak into surrounding tissue.

CLINICAL SIGNS:

DIAGNOSIS:

TREATMENT:

QUICK, AGGRESSIVE TREATMENT IS ESSENTIAL!


PROGNOSIS:

The prognosis is always guarded with a horse that has developed a clostridial myonecrosis.  The toxins produced by Clostridium species are very powerful and complications can arise that rapidly lead to death.  It is critical that any horse suspected of having clostridial myonecrosis be examined by a veterinarian as soon as possible to enable the best chance for survival. 


PREVENTION?

"An ounce of prevention is worth a pound of cure"

~Benjamin Franklin


References:

Peek, S.F. and Semrad, S.D. 2002. Equine Veterinary Education. 14(3):163-168.

Robinson E. and Sprayberry  K. 2009. Current Therapy in equine Medicine 6th Edition. Saunders.

Click Here to read this article in pdf format. 


« Back