Following recent media publicity around the proposed release of a new strain of rabbit calici virus a frequent question being asked by our clients is what this means for their pet rabbits. Hopefully this article is helpful in addressing common questions and concerns.
Calici virus or Rabbit Hemorrhagic Disease Virus (RHDV1 v321 or Czech Strain) was first introduced into New Zealand in 1997 illegally when frustrated South Island farmers imported it from Australia. Initially the virus was very effective in killing the wild rabbit population but over time 40-90% of wild rabbits have developed resistance to the virus depending on the region.
A new strain of calici virus (RHDV1-K5 or Korean Strain) has been identified by scientists and their hope is that this K5 variant (RHDV1-K5) will overcome the resistance issues. Australia is scheduled to introduce the K5 variant in autumn 2017.
Environment Canterbury on behalf of a coordinating group is seeking approval for the controlled release of the new strain into New Zealand from Ministry for Primary Industries and the Environment Protection Authority.
What are the Symptoms’ of Calici Virus Infection?
Calici virus damages internal organs such as the liver and intestines and may cause bleeding. Signs include fever, restlessness, lethargy and poor appetite with bleeding from the nose and/or blood on the floor where rabbits are housed. Often infected rabbits will show no signs and die suddenly. If your pet rabbit is showing signs you need to contact us immediately. There is no specific treatment for RHD but affected rabbits can be given supportive care. The prognosis for recovery is very poor and most rabbits die.
How does Calici virus spread?
Calici virus is highly contagious and is spread from infected rabbits in droppings, urine, secretions from the eyes and nose, and at mating. Spread can also occur from contaminated objects such as food, clothing, cages, equipment, insects (especially flies), birds and rodents. The virus is tough and survives well in the environment and the key point to note is that pet rabbits do not need direct contact with wild rabbits to become infected.
How do I protect my pet rabbit from Calici Virus?
Currently in New Zealand pet rabbits are vaccinated with Cylap vaccine to protect against calici virus. This vaccine does not claim to be effective against the new K5 strain. A small study was conducted in Australia comparing the mortality of a small number of vaccinated and unvaccinated rabbits that were subsequently infected with a high dose of K5. All of the rabbits vaccinated with Cylap survived, and none of the unvaccinated rabbits survived. Based on this information, Cylap is likely to continue to protect pet rabbits against this disease, provided that the correct vaccination protocols are followed.
We recommend that bunnies receive their first vaccination at ten to twelve weeks of age followed by a booster vaccination three to four weeks later. Rabbits older then twelve weeks only require a single vaccination. A health check and booster vaccination is recommended annually thereafter in all rabbits. These recommendations are likely to change and follow the Australian guidelines when the new K5 strain is introduced.