Official confirmation is still pending but 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 present in a variety of places in North America and it was largely a question of when (and how) it was going to get here.
More details will hopefully follow, but here are a few key points.
What’s the cause?
- Rabbit hemorrhagic disease virus (RHDV). Specifically, we’re dealing with RHDV2
What species does it affect?
- While various virus names don’t actually 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 short: 1-4 days.
What does it do?
- It can cause serious hemorrhagic disease. It usually starts with non-specific signs like fever, decreased appetite and depression (which might not be noted) and progresses to more severe signs such as difficulty breathing, neurological disease and bleeding from various sites. Often, rabbits are simply found dead, sometimes with evidence of bleeding.
How is it transmitted?
- Transmission is from direct contact with infected bodily fluids such as saliva, nasal discharges, urine and blood, as well as feces. Even contact with the haircoat can be a risk since contamination with bodily fluids and feces is common. The virus is quite resilient and transmission via fomites (contaminated objects like cages) 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 there the ‘unsurprising’ part comes in. It can be moved between areas fairly easily and once established, it has the potential to spread widely
Is it treatable?
- Not specifically. We have no treatments that target the infection itself. Treatment is uncommonly attempted because of how severe and rapidly progressive the disease is, but would consist of supportive treatment (eg intravenous fluids) to try to stabilize the rabbit while its body fought the infection. Most often, treatment is not attempted. Sometimes, it may not be allowed, depending on the regulatory response (euthanasia of exposure rabbits may be required in some situations).
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 RHDV?
- While there are a range of potential clinical signs and some are pretty non-specific, rapid death with evidence of bleeding should trigger a concern. Deaths of multiple animals around the same time should similarly raise thoughts about RHDV 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 RHDV?
- Call your vet (who should then call the Canadian Food Inspection Agency, 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 the virus.
- Do NOT just take your rabbit to the vet unannounced. That poses a risk for further transmission of the virus.
Also, if you suspect RHDV, do not allow your rabbit to have any outdoor access. If it is raised outdoors, ensure that the enclosure is well secured and do what you can to prevent any contact with wild rabbits. CFIA will provide guidance for things like manure management, and try to ensure that nothing that has been around the rabbits (eg cages) or comes from the rabbits (eg feces) leave the secured area.
Is there a vaccine?
- Yes, but it’s not as simple as giving your vet a call in most situations. There are a few vaccines but none are licensed in Canada. They can be brought in with some paperwork, but vaccination is not readily available. Vaccination can be geared up in response to outbreaks.
Beyond vaccination, how to prevent infection?
- Preventing exposure. That’s the key, and it’s easier said than done.
Some basic measures include:
- Preventing exposure of pet rabbits to wild rabbits (eg keep pet rabbits inside or have them in well protected areas where there’s no chance of close contact with wild rabbits)
- Limiting contact with other domestic rabbits
- Limiting contact of rabbits with visitors that have had contact with other rabbits
- Knowing the health status of the facility if you are getting a new rabbit. Ideally, isolate any new rabbit for 30 days.
Is it easy to kill 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, 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 it spread to people?
- No. This virus infects rabbits and, as far as we know, just rabbits.
Will there be more cases in Ontario?
- That’s hard to say at this point. Hopefully it 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 affected 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 resources:
USDA-APHIS Fact Sheet
CFIA Fact Sheet