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Rabbit Calici Virus K5 strain - what you need to know

Posted by Claire Cable on 1 March 2018

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In follow up to our previous article on the proposed release of a new K5 Calici virus strain, we wish to advise that we have received offical notification that the application for the importation and release of RHDV1 K5 in New Zealand has been successful.

VaccProposed release regions are likely to be Canterbury, Otago and Marlborough, but it is expected that the virus will spread beyond these regions over time. A date for release of the virus has not yet been advised.  It is hoped that the Korean variant (RHDV1 K5 or K5) will overcome the natural resistance that the New Zealand pest rabbit population has developed to the existing virus (RHDV1 v321). In rabbits that have not been exposed to the virus, there is no difference in morbidity and mortality between RHDV1 v321 and K5.

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 Rabbit Calici Virus 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 to protect your rabbit in Christchurch

1. Vaccination with Cylap®

Calici vaccineThe vaccination that is registered for use against RHDV1 v321 in New Zealand rabbits (Cylap®), does not claim to have efficacy against K5.  

A recent small Australian study compared the mortality of a small number of vaccinated and unvaccinated rabbits that were infected with a high dose of RHDV1 K5 thirty days post vaccination. All of the rabbits that were vaccinated with Cylap® survived the infection and none of the unvaccinated rabbits survived. Based on this study the indications are that Cylap® will provide protection against K5.

Rabbits at risk of exposure to K5 should be vaccinated with Cylap® and kept up-to-date.  Based on recommendations from the New Zealand Veterinary Association and The Melbourne Rabbit Clinic (Australia’s first dedicated rabbit and guinea pig clinic), to protect against K5 we recommend the following vaccination protocol:

1.    First vaccination at 10-12 weeks
2.    Booster vaccination at 14-16 weeks (this booster 4 week after the intial vaccination is whats termed 'off label use' as when Cylap® was registered the label recommendation was for administration at 10-12 weeks, followed by an annual booster)
3.    Annual booster vaccination ongoing

Only healthy rabbits should be vaccinated. There is a small risk of adverse reactions to the vaccine including skin reactions, inappetence and malaise.

2. Control Measures

  1. Control insects (especially flies and fleas) as much as possible both indoors and outdoors. Flies are the main vector through which the virus is spread.
  2. Remove uneaten food on a daily basis.
  3. Keep your pet rabbit indoors where possible.
  4. Rabbit-proof your backyard to prevent access by wild rabbits.
  5. Regularly decontaminate equipment and materials (e.g. cages, hutches, bowls) with either 10% bleach or 10% sodium hydroxide. 10minutes contact times is required, then rinse off.
  6. Limit contact with and handling of unfamiliar pet rabbits.
  7. Use good biosecurity measures (e.g. wash hands, shoes and clothing) after handling other people’s rabbits.
  8. Avoid cutting grass and feeding it to your rabbits if there is the risk of contamination from wild rabbits.
  9. Infected rabbits should be isolated and disposed of in a manner that will minimise environmental contamination.

If you have not had your rabbit vaccinated against calici virus, or if your rabbit is due for a booster vaccination then please book an appointment so we can get your rabbit protected against this horrible disease.