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Ask-A-Veterinarian: For cattle, getting blackleg is bad news


© St. Petersburg Times,
published September 15, 2001

Question: I grew up on a farm years ago. We raised some cattle and, whenever they got sick, my daddy and the farm hands always said it was probably the blackleg. When the old vet was called, many times he would try to tell them it was something else, but they hardly ever believed him.

So, I grew up thinking everything wrong with cattle was the blackleg. What exactly is blackleg?

Answer: Cattle can be afflicted with many, many illnesses, only one of which is called blackleg.

As you imply, blackleg probably did not cause of most of the problems among the cattle on your farm.

Blackleg is a disease of cattle and sheep caused by a bacterial infection. The bacteria are called Clostridium chauvoei and live and grow naturally in the intestinal tract of suchanimals.

Spores are the inactive, resting stage of some organisms, allowing them to live for many years. Cattle ingest these bacteria, which can pass through their gastrointestinal wall, enter the bloodstream and subsequently deposit themselves in various body tissues, particularly muscles

The disease in cattle generally occurs in summer and fall (not usually winter), more commonly among beef breeds that are in very good health and gaining weight.

Most animals get sick between 6 months and 2 years old, but young, healthy thrifty calfs can get sick at 6 weeks old and older cattle are sometimes affected at 10-12 years old. This rapidly fatal (within 12 to 48 hours) illness usually appears suddenly with fever and acute lameness with gas-filled swellings of heavy muscles.

Some cattle experience muscle damage to their heart and diaphragm muscles. Interestingly, sheep usually contract blackleg from an external injury such as a cut, tail docking or castration.

It is uncommon for them to develop the internal variety of the disease that occurs in cattle.

A safe, reliable vaccine is available to protect cattle and sheep. If outbreaks occur, your veterinarian may advise immediately vaccinating all susceptible (non-vaccinated) cattle and treating them with antibiotics for 10 days until the vaccine produces immunity.

Treatment of diseased animals is usually unsuccessful.

-- Guy Hancock, D.V.M., M.Ed., program director, veterinary technology, St. Petersburg College

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Dr. Bruce Kaplan is a veterinarian editor/writer. Please send questions to Ask a Veterinarian, Pinellas Animal Foundation, P.O. Box 47771, St. Petersburg, FL 33743-7771. Because of the volume of mail, personal replies are not possible. Questions of general interest will be answered in the Ask-A-Veterinariam column.

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