RABBIT HEMORRHAGIC DISEASE


What is it?


Rabbit hemorrhagic disease (RHD) is a highly contagious and exceptionally lethal disease of rabbits caused by the rabbit hemorrhagic disease virus (RHDV).  There are several subtypes of this virus; the two main ones are labeled RHDV1 and RHDV2.  This virus affects only the European rabbit (from which all pet and meat product rabbits derive) and does not affect native lagamorphs in Canada.


Where did it come from?


The first reported outbreak of this disease was in China in 1984 in commercially bred Angora rabbits imported from Germany. In less than a year, RHD killed 140 million domestic rabbits in China and spread over an area of 50,000 square kilometers.


From China, it spread around the world via infected rabbits and rabbit products. By the late 1990s, the virus had spread to 40 different countries and had become endemic in many areas.


Only periodic outbreaks have been reported in North America. The first report of RHD in Canada occurred in Manitoba in 2011 where an individual indoor lop rabbit died acutely. The disease reappeared in eastern Quebec in 2016 in small hobby farms and a complete cull prevented the disease from spreading.  The latest outbreak of RHD is reported in British Columbia as of February 2018.



Why are we worried now?


The British Columbia outbreak appears to be wider spread than the previous outbreaks have been.  In late February 2018, a large group of feral domesticated rabbits was found dead on Vancouver Island University Campus. Three carcasses were sent to the Animal Health Centre in Abbotsford that confirmed the rabbits had died of rabbit hemorrhagic disease.  Further testing determined the virus responsible was RHDV2.  A major feral rabbit colony die off was then reported on Annacis Island, also confirmed to be RHDV2.  Cases have since been confirmed in Nanaimo, Comox, Courtenay and Parksville on Annacis Island and in Delta and Richmond on the mainland.


What animals are susceptible to RHDV?


RHDV primarily affects wild and domesticated European rabbits (Oryctolagus cuniculus). Other lagomorphs, including European brown hares (Lepus europaeus), varying (snowshoe) hares (Lepus americanus), cottontails (Sylvilagus floridanus), black-tailed jackrabbits (Lepus californicus), white-tailed jackrabbit (Lepus townsendii), and volcano rabbits (Romerolagus diazzi), are resistant to RHDV.


RHDV2 has been show to have a slightly broader host range. In addition to European rabbits, RHDV2 can infect the Cape hare (Lepus capensis var. mediterraneus) and Italian hare (Lepus corsicanus).

This virus does not infect humans or other mammals, but both can act as vectors and spread the virus.



What are the symptoms of RHD?


The incubation period of the disease is short.  A rabbit can start show signs of illness within 1 to 4 days of exposure to the virus. 

 

The disease presents three ways:


1. Per-acute infection: rabbits die suddenly with no clinical signs or warnings. This is the most common presentation. Mortality rates are estimated at 40% to 100%.


2. Acute infection: symptoms include fever, lethargy, loss of appetite, convulsions, paralysis, incoordination, breathing difficulties, blue tinged lips or mucus membranes, and bleeding from the eyes, nose, and rectum. Most die within a day of showing signs. Rarely, an individual may survive the initial infection but will succumb to liver failure within a few days.  If the rabbit does survive, it will have permanent liver damage.


3. Sub-acute infection: some rabbits will show mild signs of infection from which they recover. These rabbits develop antibodies that protect them from re-infection however; they become carriers of the disease, potentially shedding the virus and infecting other rabbits.  The length of time carrier rabbits shed virus has yet to be determined, but viral particles have been detected in droppings of survival rabbits for as long as 15 weeks after infection.


How does RHD spread?


RHDV spreads easily and lasts a long time.  Only a few virus particles are needed to cause disease.  The virus is difficult to kill and can survive in the environment for many months, especially if protected by organic material.  Transmission can occur any of the following ways:

  1. Direct contact with live or dead rabbits

  2. Contact with contaminated feces, urine or body secretions

  3. Direct or indirect contact with contaminated items such as shoes, clothing, bedding, dishes or bottles, food, water, cages, equipment and tires

  4. Contact with contaminated rabbit fur or meat

  5. Contact with the feces of scavengers (fox, crow, coyote) that have fed on infected rabbit carcasses

  6. Biting insects – the virus has been documented to persist in flies for up to 9 days. 

  7. Ingestion of vegetation contaminated by scavengers or insects in contact with the virus


What if I find a dead rabbit?


RDH is a reportable disease.  If you find multiple dead rabbits that appear in good body condition with no obvious cause of death, report your findings to a local animal control agency or a veterinarian.  Do NOT bury any dead rabbits.  If handling the carcass, use a double plastic bag system and if the carcass is to be tested, do not freeze.  Wash hands and change and wash clothes.  Disinfect the soles of shoes and vehicle tires.

 

How do I protect my rabbit?


Control and prevention of RHD spread includes surveillance, sanitation, disinfection and quarantine.

  1. Restrict access of others to your rabbit allowing in only those people necessary for its care 

  2. Do not share equipment with other rabbit breeders/owners

  3. Avoid taking your rabbit outside on walks or to shows/fairs

  4. Avoid introducing any new rabbits into your home

  5. Avoid unnecessary contact with other people’s rabbits. If you must have contact, wash your hands or shower and change your clothes prior to handling your own rabbit

  6. Avoid contact with feral rabbits

  7. Do not collect wild plants or grasses for a food or bedding source

  8. Store feed and bedding inside and use tightly sealed containers. Ensure used feed, litter and bedding is packaged to avoid attracting feral rabbits, wildlife, or flies

  9. Prevent rabbit contact with insects, birds, rodents, or other wild animals

  10. Do not allow outdoor cats or dogs access your rabbit’s housing area

  11. Do not travel with your rabbit to areas experiencing outbreaks of the disease

  12. If traveling to an outbreak area, remember the virus can be carried on shoes, clothing and tires and transported back to your home

What if I am getting a new rabbit?


If you are introducing a new rabbit to your home, ensure they undergo a strict quarantine period, in a separate air space from your rabbit, for 60 days. During quarantine, ensure you:


- Handle, feed, and clean the new rabbit after tending to resident rabbits
- Prevent direct and indirect contact between new and resident rabbits (do not share dishes, toys,

  brushes, etc.)
- Have dedicated clothing such as slippers, lab coat or zip-up sweater to wear when

  handling/cleaning/feeding the new rabbit. Leave that clothing in the quarantine room
- Closely monitor the health of both the new and resident rabbits for signs of illness
- Report unexpected deaths to your veterinarian


What disinfectants are effective against RHDV?


All disinfection protocols should begin with a thorough cleaning of organic material from the area using hot, soapy water.  Once the area is clean, suitable disinfectants include 2% Virkon®, accelerated hydrogen peroxide (Prevail®, Accel®, and Peroxigard®), 10% household bleach, 2% One-stroke Environ®, and 10% sodium hydroxide.


Can my rabbit be treated if they get RHD?


As with all viral infections, there is no specific treatment for RHD.  Affected rabbits can be medically supported, but most die.  Survivors should be considered carriers and quarantined from other rabbits for the rest of their lives. 


Can my rabbit be vaccinated?


Yes.  The most effective vaccine to date is FilavacÒ, a bivalent vaccine manufactured in France that offers protection against both RHDV and RHDV2.  It is recommended that rabbits over 10 weeks of age receive the vaccine and then are given a booster vaccine every year.   Early vaccination at 4 weeks of age is possible, but these rabbits should receive a booster vaccine at 10 weeks of age, then annually. 

Vaccines for RHD are not currently available in Canada and their use is considered ‘off label’ which simply means the vaccine is not yet licensed in Canada.  An application must be made to Ottawa to receive an Emergency Drug Release in order to import the vaccine.


Should I vaccinate my rabbit?


We have been struggling with the right answer to this question since the B.C. outbreak was confirmed.  If it follows previous scenarios, we hope to see it self-limit and end.  However, given this outbreak started in feral rabbits and no move has been made to cull or control that population, we feel there is significant enough a risk to make vaccination prudent.  This is a hardy virus that spreads easily and quickly with devastating results. 


As with all vaccines, there are reported downsides to its use (abscesses, inadequate protection, anaphylactic response) and owners will need to make their own personal decision on whether or not to proceed and vaccinate their pet.  Again, the virus has not been diagnosed in Alberta.  Our decision to bring the vaccine in from France and vaccinate pet rabbits is like buying insurance – we hope we never need it but we want to have it if we do.   

 

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