Rabbit hemorrhagic disease is a highly fatal disease in domestic rabbits and some types of the virus are deadly for wild rabbits.
RHD is considered a foreign animal disease in the United States. The disease poses no threat to humans. The disease is caused by a calicivirus which has three different pathogenic groups. In the spring of 2020, the disease was found in wild and domestic rabbits in the states of Arizona, New Mexico, Colorado, Texas, and Nevada. Oklahoma rabbit owners need to be aware of this emerging threat.
The virus is highly contagious. It spreads through direct contact between infected rabbits. A dead carcass of a positive rabbit contains large amounts of the virus and the virus survives for long periods of time in the decaying tissues. Other means of spread are through meat, fur, contaminated food and water, or other materials that come in contact with the virus. Biting insects can transfer the virus from animal to animal. Humans can spread the virus on shoes or clothing. The virus is thought to be found in all rabbit secretions such as urine, feces, blood, and respiratory secretions of infected rabbits.
The first clinical signs that most people observe with RHD are dead rabbits with dried blood in the nasal passages. Other signs seen are anorexia, dullness, vocalization, respiratory signs (increased respiration rate, frothy and bloody nasal discharge), neurological signs (ataxia, paddling, convulsion, paralysis), and cyanosis of the mucous membranes. If the disease continues to progress, the animal will show signs of jaundice, lethargy, and weight loss. These animals will usually die of liver failure, but some will survive. Diagnosis is based on clinical signs and laboratory testing.
There is no specific treatment for RHD. Sick rabbits should be isolated from all other rabbits and owners should consult with their veterinarian. Veterinarians will provide supportive care, but the best option of controlling the disease is to focus on preventing the disease. Other countries have a RHDV2 vaccine, but the vaccine is not approved for use in the U.S. The only means of preventing RHDV2 is biosecurity. The USDA recommends the following biosecurity protocols:
• Do not allow pet, feral, or wild rabbits to have contact with your rabbits or gain entry to the facility or home.
• Do not allow visitors in rabbitries or let them handle pet rabbits without protective clothing – including coveralls, shoe covers, hair covering, and gloves.
• Always wash hands with warm soapy water before entering your rabbit area, after removing protective clothing and before leaving the rabbit area.
• Do not introduce new rabbits from unknown or untrusted sources. Do not add rabbits to your rabbitry from animal shelters or other types of rescue operations.
• If you bring outside rabbits into your facility or home, keep them separated from your existing rabbits. Use separate equipment for newly acquired or sick rabbits to avoid spreading disease.
• Sanitize all equipment and cages moved on or off premises before they are returned to the rabbitry. We recommend disinfecting with 10 percent bleach or 10 percent sodium hydroxide mixed with water.
• Establish a working relationship with a veterinarian to review biosecurity practices for identification and closure of possible gaps. Rabbit owners should review their biosecurity plan. If they do not have a biosecurity protocol, they should consult with their veterinarian and develop one.
If an individual finds several dead rabbits in the wild or a rabbit owner suspects the disease in their rabbits, they should contact their local veterinarian or Dr. Rod Hall at the Oklahoma Department of Agriculture, Food, and Forestry at 405-522-6141.
For additional information, a fact sheet from the USDA can be found at www.aphis.usda.gov/publications/animal_health/fs-rhdv2.pdf.
Roger Williams is an agriculture educator for the Oklahoma Cooperative Extension Service in Cherokee County.