UPDATE JULY 2017: There is more evidence that the current Cylap vaccine is effective. A further study (reference below) has demonstrated 100% protection in a small group of rabbits experimentally exposed to K5 virus.
In early March 2017, the new K5 strain of calicivirus is planned to be released at 600 sites across Australia and 45 in South Australia. Here’s what pet rabbit owners need to know.
What Is K5 Rabbit Calicivirus?
K5 is a Korean rabbit calicivirus deliberately selected to kill more rabbits in cooler and wetter areas such as the Adelaide Hills and South East Australia. Whatever you think about the needs of farmers, it’s a time of great concern for pet rabbit lovers.
Confusingly, there have been four other calicivirus strains in the news.
- The ‘classic’ Czech strain of Rabbit Haemorrhagic Disease Virus released in 1995.
- A Chinese RHDVa strain was found in NSW in 2014 and is of uncertain significance.
- RHDV2 calicivirus spread into Adelaide in February 2016: follow the link to read more.
- Cats get an unrelated calicivirus and are not affected by the rabbit virus.
Death occurs rapidly, typically in 1-2 days, often without obvious warning signs. Rabbits may show symptoms of listlessness and poor appetite. The rapid onset of illness has led some authorities to suggest that calicivirus is a humane form of rabbit control. I disagree; as a vet, I believe the only humane death is an instantaneous one.
How To Protect Pet Rabbits From Calicivirus
- Vaccination is likely to be protective, based on a small study.
- Flies and other insects are know to spread the virus. Use insect repellents and fly screens around rabbit enclosures, and try to keep unprotected rabbits inside.
- Prevent contact with wild rabbits (including grass or hay where wild rabbits feed).
- Practise good rabbit flea & parasite control.
- Clean hands and any items in contact with rabbits or rabbit faeces, especially shoes.
- Isolate new arrivals and infected rabbits; please contact us in SA with any suspected deaths.
K5 & The Australian Calicivirus Vaccine
There is some hope that the existing Cylap vaccine will continue to protect rabbits against K5.
Vaccine protection of rabbits against the new RHDV2 has been disappointing. However, the K5 strain is more closely related to the classic strain from which the vaccine was originally developed.
In very small Australian trial the vaccine protected rabbits against exposure to K5. Although the evidence is only sketchy, I expect the vaccine to work this time. Here’s what we are recommending to vaccinate rabbits against K5 calicivirus:
- Vaccination at 8 and 12 weeks of age
- Annual vaccination thereafter
Note that this contradicts 6-monthly Australian Veterinary Association advice (developed for RHDV2) but is in accordance with the manufacturer’s guidelines for the original Czech strain.
Lastly, don’t panic. I hope I’m not proved wrong, but my gut instincts tell me that this release will be ‘disappointing’ for those interested in rabbit control. In other words, a relief for you and I. Please get your rabbit vaccinated!
Vaccine challenge study ( copies available on request): Read, A. and Kirkland, P. (2017), Efficacy of a commercial vaccine against different strains of rabbit haemorrhagic disease virus. Aust Vet J, 95: 223–226.
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By Andrew Spanner BVSc(Hons) MVetStud, a vet in Adelaide, Australia. These help topics are from a series regularly posted on Facebook and Twitter. The information provided here is not intended to be used as a substitute for going to the vet. If your pet is unwell, please seek veterinary attention.