Rabbit hemorrhagic disease has been identified in a group of pet rabbits in Lambton County, Ontario. This is a bit of a “surprising, but not surprising” scenario, as this highly contagious virus of rabbits is already present in at least 21 US states and 2 Canadian provinces (Alberta and BC), so it was largely a question of when (and how) it was going to get to Ontario.
More details will hopefully follow, but here are a few key points to keep in mind:
What’s the cause of rabbit hemorrhagic disease?
- Rabbit hemorrhagic disease virus (RHDV). Specifically, we’re dealing with RHDV2.
What species does RHDV2 affect?
- While many virus names don’t correspond to their true hosts (yes, monkeypox, I’m talking about you), this one does. Rabbits and hares (wild and domestic) are the hosts and the only species that are susceptible. Potential impacts on wild rabbits are of significant concern since large scale mortality events are possible.
What’s the incubation period?
- The time from exposure to the virus to development of disease is typically 1-4 days.
What are the signs of infection?
- The virus, as the name suggests, can cause serious hemorrhagic disease. It usually starts with non-specific signs like fever, decreased appetite and depression (which might not be noticed) and progresses to more severe signs such a difficulty breathing, neurological disease and bleeding from the nose or mouth caused by internal bleeding. Often infected rabbits are simply found dead, sometimes with evidence of bleeding.
How is the virus transmitted?
- Transmission is from direct contact with infected bodily fluids such as saliva, nasal discharge, urine, blood, and feces. Even contact with the animal’s haircoat can be a risk since contamination of the fur with bodily fluids or feces is common. The virus is quite resilient and transmission via fomites (e.g. contaminated items like cages or even feed) is a concern. It can also be transferred by people on clothing or other items. There’s even the potential that cars can track the virus between areas on their tires. This high degree of transmissibility is why finding the virus in Ontario is in some ways “unsurprising,” because it can be moved between areas fairly easily and once established, it has the potential to spread widely.
Is RHD treatable?
- We have no treatments that target the virus itself. Treatment is uncommonly attempted because of how severe and rapidly progressive the disease is, but consists of supportive care (e.g. intravenous fluids) to try to stabilize the rabbit while its body fights the infection. Sometimes, attempting treatment may not even be allowed, depending on local regulations (euthanasia of exposed rabbits may be required in some jurisdictions).
Do recovered rabbits pose a risk to other rabbits?
- Recovered rabbits can shed RHDV2 for a while. The risk is probably mainly over 4-6 weeks after recovery but longer shedding periods cannot be ruled out.
When should someone be concerned about RHD?
- While there are a range of potential clinical signs of this disease and some are pretty non-specific, rapid death with evidence of bleeding should be the main trigger for concern. Deaths of multiple animals around the same time should similarly raise thoughts about RHD unless there is another likely cause. In a situation where the disease might be emerging, it’s best to get testing done when there’s any reasonable suspicion.
What should I do if I suspect my rabbit has RHD?
- Call your veterinarian. Your veterinarian should then call the Canadian Food Inspection Agency (CFIA), the organization in charge of federally reportable animal diseases. Your provincial animal health ministry will also likely be looped in quickly). A test is available to detect RHDV2.
- Do NOT just take your rabbit to a veterinary clinic unannounced. That poses a risk for further transmission of the virus.
Also, if you suspect RHD in your rabbit or in wild rabbits in your area, do not allow your rabbit to have any outdoor access. If your rabbit lives outdoors, ensure that its enclosure is well secured and do what you can to prevent any contact with wild rabbits. If your rabbit is infected, CFIA can provide guidance for things like manure management, and ensuring that nothing that has been around the rabbits (e.g. cages) or comes from the rabbits (e.g. feces) leave the secured area.
Is there a vaccine RHDV?
- Yes, but getting the vaccine is not as simple as making an appointment with your veterinarian, because none of the available vaccines are licensed in Canada, although they can be imported with some paperwork. Vaccination can be geared up in response to outbreaks.
- [UPDATE…it’s now available in Canada. See this post for details.]
Beyond vaccination, how do you prevent infection with RHDV?
- By preventing exposure to the virus. That’s the key, but it can be easier said than done.
Some basic biosecurity measures include:
- Preventing exposure of pet rabbits to wild rabbits (e.g. keep pet rabbits inside or have them in well protected areas where there’s no chance of close contact with wild rabbits)
- Limiting contact of rabbits with other domestic rabbits
- Limiting contact of rabbits with visitors that have had contact with other rabbits
- Knowing the health status of any facility from which you get a new rabbit. Ideally, isolate any new rabbit for 30 days.
- Controlling insects, fleas and ticks on and around pet rabbits
Is it easy to kill RHDV in the environment?
- No, it’s a pretty hardy virus. It can survive outside the host for months, in the right conditions. Accelerated hydrogen peroxide, peroxygen compounds (Virkon) and bleach are effective disinfectants, if used right. A big component of that is making sure surfaces have been cleaned first. You can’t disinfect heavily soiled surfaces or items such as dirt floors. Surfaces need to be cleaned to minimize the amount of debris before the disinfectant is applied.
Can RHDV be spread to people?
- No. This virus infects rabbits and hares but, as far as we know, just rabbits and hares.
Will there be more cases of RHD in Ontario?
- That’s hard to say at this point. Hopefully the virus hasn’t spread and the source has been identified and contained. Details about that aren’t yet available. It’s hard to say if this group of rabbits is the only infected group or the only group known to be infected. Hopefully it hasn’t spread to wild rabbits. Monitoring for that and trying to ensure no spillover into wild rabbit/hare populations have to be priorities at this point.
Some additional resources on rabbit hemorrhagic disease: