Use necropsies to provide answers to clostridial disease

When a cow or calf dies unexpectedly, you may debate whether to call a veterinarian. A necropsy is the right thing to do, but will it be worth the expense?

The answer is almost always yes, said Dr. Glenn Songer, microbiologist at the University of Arizona.

“My belief is that diagnostic investigation should be a priority, even if you think you know exactly what is going on,” reported Songer to attendees at a Clostridium perfringens Type A symposium during the Western Veterinary Conference in Las Vegas, Nev. “Diagnosis is the only way to know the true cause of death. You need this information to prevent future losses, especially with emerging diseases like C. perfringens Type A infection.”

C. perfringens Type A produces alpha toxin and is implicated in deadly gastrointestinal diseases, such as abomasal ulcers and hemorrhage in calves.  Some speculate that it is involved in the pathogenesis of hemorrhagic bowel syndrome (HBS) in cows.

There is much confusion surrounding C. perfringens Type A, as C. perfringens Type A and Type C cases in calves will look almost identical in histopathology. Diagnostic follow-up work needs to be done in every case.

The first step in obtaining an accurate diagnosis is to call a veterinarian as soon as possible after a death. Samples must be from an animal that died very recently. “The best specimen for necropsy is a typically affected, untreated calf,” said Songer.

An accurate diagnosis also involves good communication. Your veterinarian will submit a field necropsy report along with tissue samples to the diagnostic laboratory. He or she will want a complete history of the case. The diagnostic lab requests information such as the breed, type of operation, age of animal, clinical signs, treatments, if other cases have been observed and if any other diseases are occurring in the herd.

Songer urged producers to be diligent. “Don’t stop with one calf,” said Songer. “Focus on the herd. I know it’s costly, but the answer lies with diagnostics. Losing animals is much more expensive than necropsies and diagnostics. The more animals we look at, the more we learn and the sooner we can control this disease.”

If diagnostic results suggest C. perfringens Type A, Songer recommends developing a management strategy with your veterinarian. For example, HBS cases may be addressed by correcting nutritional and environmental factors that are promoting clostridial overgrowth.

Currently, only one cattle vaccine has demonstrated reasonable expectations of efficacy against alpha toxin. Clostridium Perfringens Type A Toxoid is available under conditional license from Novartis Animal Health US, Inc. The product can be given to pregnant or non-pregnant animals, and has been demonstrated to be safe in calves as young as one month of age.

“Work with your veterinarian to develop a preventive management program,” urged Songer. “You probably won’t eliminate every death, but there are steps you can take to minimize losses. Your veterinarian can help you determine if options like vaccination will work in your operation.”

Novartis Animal Health researches, develops and commercializes leading animal treatments that meet the needs of pet owners, farmers and veterinarians. Headquartered in Basel, Switzerland, Novartis Animal Health conducts business in 40 countries and employs about 2,700 people worldwide. For more information, visit www.livestock.novartis.com.

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