Table Topic: Infectious Disease

Several topics were discussed at the infectious diseases table topic at the 2008 American Association of Equine Practitioners Convention held in San Diego, Calif. Bonnie Barr, VMD, from Rood & Riddle Equine Hospital, and Josie Traub-Dargatz, DVM, Dipl. ACVIM, from Colorado State University, facilitated the session.

The first topic discussed was rabies vaccination. In some parts of the United States the rabies vaccine is not routinely administered, but now the AAEP has listed this vaccine as one of its core vaccinations. Core vaccinations are defined by the American Veterinary Medical Association as vaccines that protect from diseases that are endemic, pose a risk of severe disease, and have a potential for zoonosis (transmission from animals to humans). Based on the fact that all mammals are at risk for rabies and that horses with rabies can develop a wide variation of clinical signs, most agreed that the vaccine is necessary in all regions of the continental United States. There was a discussion that the rabies vaccine for horses is safe and undergoes rigorous efficacy testing.

Lawsonia intracellularis, the causative agent of proliferative enteropathy (a spreading disease involving the intestines) in weanlings, was the next topic discussed. The discussion started with an overview of the disease, including clinical signs, diagnosis, and treatment. Treatment typically includes appropriate antimicrobials and supportive care. Questions were asked about the prevalence of the disease and possibility of a vaccine.

Surveillance guidelines for the general equine population were briefly mentioned. The discussion focused on state testing for infectious diseases, specifically what types of tests are performed. Two state veterinarians were in the audience and commented that requirements for the testing for detection of infectious disease vary from state to state.

Methicillin-resistance Staphylococcus aureus (MRSA) was discussed. The discussion focused on hospital infections with this organism. In human hospitals MRSA can result in nosocomial infections that can result in increased hospital stay. A similar scenario has been noted in veterinary hospitals. MRSA is found in the nose of healthy horses and usually does not cause a problem unless the horse is stressed. In the hospital MRSA can result in surgical site infections. Precautions should be taken to reduce the risk of infection, including isolating the horse with the infection, the use of barrier clothing (gloves, boots, and gowns) and improvement in hand hygiene among people who work with horses. The best treatment oftentimes is topical treatment of the infected area instead of administration of systemic antibiotics.

The session ended with a brief discussion about Corynbacterium psdeudotuberculosis, which causes pigeon fever (also known as dryland distemper).

About the Author

Bonnie Barr, VMD, Dipl. ACVIM

Bonnie Bar, VMD, Dipl. ACVIM, is a shareholder at Rood & Riddle Equine Hospital, in Lexington, Kentucky.

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