Alberta is on the lookout for dead rabbits. The province has witnessed several cases of a deadly strain of Rabbit Hemorrhagic Disease Virus known as RHDV2.
The virus has killed numerous rabbits over the last year, including five pet rabbits in Taber in May 2021, three young bunnies from a group of feral domestic rabbits—meaning they were either pets released into the wild or the offspring of pets—in northwest Edmonton in September 2021, and three colonies of feral domestic rabbits in Calgary between late August and early September 2022.
Previously, RHDV was only found in Alberta’s feral domestic rabbits, but among the most recent deaths was a wild mountain cottontail rabbit. The difference between wild and feral rabbits is that wild rabbits are native to the environment while feral rabbits come from stock once domesticated or imported from other countries. Wild rabbits were thought to be immune to RHDV, but the RHDV2 strain is infecting wild populations. This was the first wild rabbit found dead from the virus in the province, said Alberta’s Ministry of Environment and Parks in a report. The ministry wants to prevent the virus from becoming embedded in Alberta’s wild rabbit populations.
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Researchers first diagnosed RHDV in China in 1984. Since then, the virus has spread through Europe, Australia, New Zealand, Cuba, and some parts of Asia and Africa, the ministry said in an email.
In 2010, researchers diagnosed RHDV2, a new strain, among the European rabbit species in France. RHDV2 has since appeared in North America. Feral domestic populations of European rabbits were killed by the virus in Quebec in 2016, British Columbia in 2018, and Washington State in 2019.
RHDV2 has a mortality rate of 70 to 100 per cent. Once a rabbit is exposed, it can become sick within one to five days, and the virus will quickly tear through the rest of its colony. According to the Canadian Food Inspection Agency, the virus is spread between rabbits through direct contact with infected saliva, runny nose and eyes, urine, manure, blood, and infected fur or carcasses.
Common symptoms include fever, loss of appetite, shortness of breath, groaning, blood spots in the eyes, frothy and bloody nose, and neurological symptoms, such as difficulty walking, seizures, or paralysis.
Beyond the wild mountain cottontail found dead in September, experts haven’t found the virus in any other wild rabbits in Alberta. But this doesn’t mean it won’t spread. Since the spring of 2020, the southwestern U.S. and northern Mexico have experienced multiple outbreaks among their wild rabbit populations.
Arizona was the first state in the U.S. where the virus transferred from feral domestic rabbits to wild rabbits. In April 2020, a wild black-tailed jackrabbit and several wild cottontails were found dead from the virus.
“The virus escaped from captive and pet rabbits into adjacent feral populations of domestic rabbits as well as native wild rabbits and hares,” the ministry said. “The social nature and natural high density in populations of rabbits and hares facilitates viral transmission. All forms of rabbit haemorrhagic disease are highly contagious, with high mortality rates in susceptible species and populations.”
Environment and Parks’ Wildlife Disease Unit is monitoring wild hares, jackrabbits, and cottontail rabbits in the vicinity of outbreaks for signs of the virus. It’s also asked any members of the public to report sightings of groups of dead rabbits.
The ministry does stress that outside of rabbits and hares, RHDV2 is not contagious among humans, pets, livestock, or other animal species. But humans are helping to transmit the disease. By purchasing pet rabbits from questionable sources, not taking proper hygienic care of the rabbits and their enclosure, and abandoning pet rabbits in the wild, the virus can spread.
To prevent further infections, the ministry suggests washing your hands, clothes, cages, and equipment between contacts with rabbits from different sources, only taking in rabbits from reputable sources, quarantining new rabbits away from existing ones for 30 days, using separate equipment for new or sick rabbits, and preventing all contact with wild rabbits, hares, and jackrabbits.
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