Veterinarians Watch for Hurricane-Related Illnesses

With water pooling everywhere and sharp debris all around, horse owners can't help but wonder if conditions left by Hurricanes Katrina and Rita will cause an increase in illnesses such as tetanus, encephalitis, botulism, and Potomac horse fever (PHF). Area veterinarians say they haven't seen an increase in horses exhibiting these diseases, but they're remaining on guard should any hurricane-related cases flare.

Shannon Gonsoulin, DVM, owner of All Creatures Animal Hospital in New Iberia, La., helped rescue and treat horses after the hurricanes. "The biggest threats are, in the immediate term, tetanus, and in the long-term, mosquito-borne viruses," he says.

Tetanus--By far the most equine cases Gonsoulin has seen directly related to the hurricane have been lacerations from debris. "Fortunately, we recommend the tetanus vaccine quite frequently down here," he said. "We haven't had any tetanus cases at this point that have developed in association with either hurricane. I'm sure there's one or two that we might not have noticed, but tetanus seems to be under control."

Becky McConnico, DVM, PhD, Dipl. ACVIM, associate professor of veterinary medicine in Louisiana State University's Equine Health Studies Program, has seen one case of tetanus that she believes is attributable to a Katrina-related injury. The horse was not vaccinated against tetanus and the owner elected to euthanatize the horse.

Encephalitis--There are differing opinions on the exponential growth of mosquito populations and their likelihood of causing outbreaks of encephalitis such as Eastern equine encephalitis and West Nile virus. Katrina and Rita left standing water all over the Gulf Coast, creating ideal mosquito-breeding conditions. Veterinarians are remaining cautious, because a mild winter could stretch out the mosquito season, making the threat of encephalitis last longer. (For more information on post-hurricane encephalitis, see

Botulism--Still another post-hurricane concern could be botulism, which sometimes appears in areas where soil has become warm and moist for an extended period of time or where there are decaying or decayed bits of forage and/or dead animals. In such a situation, horses get botulism when toxins from the bacterium Clostridium botulinum are introduced into their bodies by either ingestion or contamination of wounds. The toxins produced by C. botulinum can cause weakness, since they block the connection between nerves and muscles and eventually paralyze the horse.

So far, there doesn't appear to be any increase in horses with botulism as a result of the hurricanes. Part of the reason could be that horses aren't grazing in areas where carcasses remain from the storm, because in those areas the grass has been killed by the salt water (see page 18 for more on post-hurricane pastures).

"Right now they're trying to pick up all the dead carcasses they can and burn them to decrease the chance of a botulism exposure," Gonsoulin said. "Unfortunately, a lot of these carcasses have washed out to some of the marshes that are pretty remote."

Other nasties--McConnico says other types of hurricane-related disease that could appear in the coming months are pythiosis (which is caused by a water-borne agent and characterized by large granulomatous or chronically inflamed lumps or swellings under the skin with yellow-gray dead tissue masses or cores; see photo at left) and other fungal skin diseases. Additionally, she anticipates there could be an increase in corneal (eye) disease secondary to trauma from debris.

Other veterinarians have suggested that ingestion or exposure to another agent, Leptospira spp., could be on the rise. Leptospirosis can cause abortion, infertility, lowered milk production, and equine recurrent uveitis (moon blindness), and it is thought to be contracted through ingestion of contaminated soil or feedstuffs, or via cuts. At least one veterinarian has suggested there might be more uveitis cases because of conditions left by the hurricanes.

Potomac horse fever (another disease that tends to show up in some areas as a result of wet weather) isn't found in Gulf Coast areas, but veterinarians say to stay tuned, because one never knows if it will appear.

Gonsoulin concluded, "We're still in the infant phase, and we're not sure what we might see. We're hoping for the best and expecting the worst for any kind of disease outbreaks."

About the Author

Stephanie L. Church, Editor-in-Chief

Stephanie L. Church, Editor-in-Chief, received a B.A. in Journalism and Equestrian Studies from Averett College in Danville, Virginia. A Pony Club and 4-H graduate, her background is in eventing, and she is schooling her recently retired Thoroughbred racehorse, Happy, toward a career in that discipline. She also enjoys traveling, photography, cycling, and cooking in her free time.

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