Rabbit hemorrhagic disease, highly contagious disease with a high mortality rate, is threatening North America’s wild rabbits.The U.S. Department of Agriculture’s (USDA) Animal and Plant Heath Inspection Service classified the virus serotype 2 (RHDV2) “as a foreign animal disease…for the first time in the U.S., detected in wild rabbits.”

This virus was first reported in China in 1984, and spread to Asia, Europe, and Australia. The first case in the U.S. was in 2018.

“RHDV2 is highly contagious and, unlike other rabbit hemorrhagic disease viruses, it affects both domestic and wild rabbits. Many times, the only signs of the disease are sudden death and blood-stained noses caused by internal bleeding. Infected rabbits may also develop a fever, be hesitant to eat, or show respiratory or nervous signs,” according to a USDA fact sheet.

Rabbits raised for human consumption and the pet trade are believed to be the source of the disease, which is transmitted through contact with infected rabbits or carcasses, their meat or fur, or contact with contaminated food, water or bedding.

Humans and dogs are not susceptible to rabbit hemorrhagic disease. It’s very specific to rabbit species.

 

RHDV2 can persist in the environment for long periods of time. It can survive freezing temperatures and four months in dry conditions.

An outbreak of the disease in the U.S. started in New Mexico in March 2020 when an infected rabbit was confirmed. Since then, RHDV2 has continued to spread in New Mexico and across multiple states, including Arizona, California, Colorado, Nevada, and Texas. Wild rabbit populations impacted by the disease include desert cottontails, mountain cottontails, black-tailed jackrabbits and antelope jackrabbits. Lab tests confirmed that eastern cottontails are susceptible to the disease.

“The average mortality rate is 20 percent, which is extremely high when you are talking about populations of millions,” said Christine Casey, DVM, state wildlife veterinarian, in a video presentation to the Kentucky Fish and Wildlife Commission. “The disease is spreading rapidly and it causes significant loss to populations.”

In a website posting the Kentucky Department of Fish and Wildlife Resources (KDFWR) said “the potential introduction of this virus to Kentucky through the movement of animals for commercial and recreational activities is a serious concern.”

The Kentucky Fish and Wildlife Commission, at its May 22 quarterly meeting, recommended a ban on the importation and transportation through Kentucky of native and exotic rabbit species in an effort to diminish the risk of spreading rabbit hemorrhagic disease into Kentucky.

Biologists are concerned that the virus could severely impact Kentucky’s native rabbits, especially two species of concern, the Appalachian cottontail and swamp rabbit, whose populations are already declining.

Kentucky has three species of rabbits, but only the eastern cottontail is found statewide. Populations of swamp rabbits and Appalachian cottontails are much smaller, and found regionally.

• The eastern cottontail, Sylvilagus floridanus, is present in all 120 Kentucky counties. In fact, the eastern cottontail is the most abundant of the nine species of cottontail rabbits found in the U.S.

Historically, the highest populations have been in the Knobs/Outer Bluegrass Region and the Eastern Coalfields. This is because rabbit numbers are tied to early stages of plant succession, which includes areas where timber has been harvested, or where soil has been disturbed by agriculture.

Adults weigh two to four pounds and coloration is brownish gray, with black and white hairs.

Cottontails are quite agile, able to run up to 18 miles per hour and can jump 10 to 15 feet.

• The swamp rabbit, Sylvilagus aquaticus, is the largest of the three species, and found in western Kentucky, associated with river bottom wetlands, and islands in the lower Ohio and Mississippi Rivers.

Swamp rabbit numbers have declined because of the loss of habitat. There are isolated pockets with higher numbers, but no means is this rabbit abundant. Populations tend to fluctuate greatly from year to year.

River bottom hardwoods, that periodically flood, and canebrakes, are preferred habitat. Swamp rabbits have been found as far east as the lower Green River, but they are more common in the Purchase Region.

Swampers have a home range of 11 to 27 acres. They are at home in water, with webbing between their toes to help them swim and walk through mud. They have been known to hide underwater with only their nose above the surface.

Adults can weigh up to six pounds and distinctive coloration includes rust-colored feet and a black spot between their ears.

Swamp rabbits run in a zigzag pattern and in a burst of speed can reach an unbelievable 48 miles per hour.

• The Appalachian cottontail, Sylvilagus obscurus, lives in the same habitat as the ruffed grouse.

It is strictly a woodland species, but often found around abandoned hill farms, or reclaimed strip mines.

Very similar in coloration to the eastern cottontail, the Appalachian cottontail is the smallest of the three species. It can only be differentiated from the eastern cottontail by details on their skulls. It was not described in the scientific literature as a separate species until 1992.

This rabbit has been found in some counties of the Cumberland Plateau, as far west as Lincoln and Boyle counties, but not much is known about its distribution in eastern Kentucky.

Like the ruffed grouse, numbers of Appalachian cottontail rabbits have declined because forests in eastern Kentucky’s mountain counties are growing into maturity, with less open land in shrubs, undergrowth, and saplings.

The Appalachian cottontail is found at high elevations from Pennsylvania to South Carolina, and is closely related to the New England cottontail, Sylvilagus transitionalis.

Wildlife biologists, veterinarians and wildlife administrators are watching this issue closely because rabbit hemorrhagic disease, virus serotype 2 (RHDV2), has the potential to severely impact wild rabbit populations in Kentucky, and all across North America.