Don't Let Rabbit Fever Strike Your Pet

Published Jul. 14, 2014

Pet owners in my home town have recently had a reminder as to why it’s not a good idea to let dogs and cats roam freely and why parasite prevention is so important. Tularemia, a disease caused by infection with Francisella tularensis bacteria, was recently diagnosed in a wild rabbit in the southeast part of Fort Collins. Rabbits in this area have been dying in unusually high numbers over the last few weeks, and until a necropsy on this particular animal was performed, nobody knew why.

Tularemia affects many different species of animals including people, dogs, and cats. Infections can develop in a couple of different ways:

handling a sick or dead animal that harbors the bacteria
eating the un- or under-cooked flesh of animals infected with the bacteria, which applies to canine, feline, and human hunters
through the bites of insects, most commonly ticks or deer flies

It is also possible to develop tularemia after eating or drinking contaminated food or water or by breathing in airborne bacteria, but these routes of transmission are less common than those mentioned above.

The Department of Health and Environment in Larimer County, Colorado, reports that the “typical signs of infection in humans are fever, chills, headache, muscle aches, chest pain, and coughing. If tularemia is caused by the bite of an infected insect or from bacteria entering a cut or scratch, it usually causes a skin ulcer and swollen glands. Eating or drinking food or water containing the bacteria may produce a throat infection, stomach pain, diarrhea and vomiting.”

Cats are more susceptible to tularemia than are dogs, with young animals being at higher risk than adults. Mildly infected animals may only suffer from a brief period of poor appetite, lethargy, and a low grade fever that resolves without treatment. More severely affected individuals can suffer from dehydration, draining abscesses, jaundice, ulcers in and around the mouth, eye infections, swollen lymph nodes, enlarged liver and/or spleen, and high fevers.

A definitive diagnosis of tularemia is based on a combination of the potential for exposure, the presence of typical clinical signs and changes in basic lab work (e.g., evidence of infection, low platelet counts, and liver involvement), and a specific test for exposure to the bacteria. Treatment with certain types of antibiotics is usually quite effective, as long as it is started in a timely manner. Dogs and cats who are suspected or known to have tularemia need to be isolated, and the people who are treating them should wear gowns, masks, and gloves and take other biosecurity measures to protect themselves and others. Cases of tularemia need to be reported to the appropriate regulatory agencies.

The Larimer County Department of Health and Environment makes the following recommendations for the prevention of tularemia in people and pets:

Avoid handling dead [or sick] animals;
Leash your pets when outdoors and keep them away from dead [or sick] animals.
If a dead animal must be moved, avoid direct contact with it. Put on a repellent to protect yourself from its fleas or ticks, and use a shovel to scoop it up. Place it in a plastic bag and dispose in an outdoor trash receptacle. Wash your hands well afterwards.
When outdoors near places where rabbits or rodents are present, wear an insect repellent containing DEET.
Keep pets confined and away from dead [or sick] animals.
Routinely use a tick and flea preventative on pets. Read the label and consult your veterinarian if you are unsure what to use.