Myxomatosis vaccination of pet rabbits

Position Statement

Steps should be taken to introduce a safe and effective myxomatosis vaccination program to protect the health of pet rabbits while not impacting unfavourably upon the control of the wild population.  Given the significant economic issue of pest rabbits the vaccination program should be accompanied by a licensing program placing the responsibility on breeders to ensure rabbits are sold neutered and microchipped. 

Background

  • Rabbits have become increasingly popular as pets worldwide. 
  • Rabbits were introduced into Australia in the late 18th century.  However, after some rabbits were released for hunting in 1859, they spread rapidly due to their early sexual maturity, short gestation periods and ability to have large litters. 
  • Rabbits are now considered to be a significant pest species in Australia because they reduce the regeneration of native plants, compete with native animals for food, contribute to soil erosion as a result of overgrazing and are a source of food for other pest predators.
  • In Queensland, the rabbit is declared to be a Class 2 pest species and the keeping of pet rabbits is prohibited.  Other Australian states and territories permit the keeping of pet rabbits but wild rabbits are still classified as pests.
  • Because of the extent of the pest rabbit problem, the myxoma virus, a member of the Poxviridae, was released in December 1950, as a method of biological control as it affects rabbits of all ages, has a short incubation period and causes a high level of mortality.  At the time, it caused a dramatic reduction in the wild rabbit population.  Over the years, however, there has been a natural selection of those wild rabbits more resistant to myxomatosis.
  • Today, myxoma virus is widespread throughout Australia.  It can be spread by direct contact with infected rabbits but it is most commonly spread indirectly (i.e. by fleas and other biting insects) thus exposing farmed and pet rabbits to the risk of infection.
  • There is no effective treatment for myxomatosis. 
  • In Australia, vaccination against rabbit calicivirus (which can cause another fatal disease in pet rabbits known as Viral or Rabbit Haemorragic disease (VHD or RHD)] is permitted because these vaccines contain an inactivated virus. 
  • Vaccination against myxomatosis is not permitted in Australia, as historically, the 2 commercially available vaccines have contained live virus strains (see Appendix).  Use of live virus vaccines have the potential to spread the attenuated myxoma virus into the wild rabbit population potentially resulting in reduced efficacy of myxomatosis as a form of biological control in the wild rabbit population.  This could lead to a dramatic increase in the number of wild rabbits in Australia, which would further exacerbate economic loss and damage to the environment.2 

Issues

  • The enormous cost to rural industries of environmental damage caused by wild rabbits
  • The enormous economic cost of wild rabbit control to rural industries
  • The lack of a proven safe and effective myxomatosis vaccine for use in Australia.

Responses

  • The development of an inactivated vaccine would preclude the spread of live virus in the wild population
  • In the event of the escape of a pet rabbit, compulsory neutering would remove any chance of a population establishing, and would minimise any environmental or economic impact. 
  • Escaped pet rabbits are likely to quickly die from predation or disease.

Guidelines

  • All pet rabbits should be kept under a licence that is renewable annually
  • Breeders should only be able to supply a pet rabbit that is neutered and microchipped.
  • It is recommended that all pet rabbits be vaccinated once a safe vaccine is established that does not impact on the pest rabbit problem.  This will be an owner responsibility.
  • The Australian Veterinary Association (AVA) should become a stakeholder group in the Rabbit Research and Control Advisory Group, and contribute to the Queensland Rabbit Pest Management Strategy.

Conclusion4

References

  1. Rabbits control in Queensland – A guide for land managers http://www.daff.qld.gov.au/4790_11065.htm Accessed March 1, 2013.
  2. A Statement from the Chief Veterinary Officer (Australia) on myxomatosis vaccine availability in Australia. Department of Agriculture Fisheries and Forestry, April, 2011. http://www.daff.gov.au/animal-plant-health/animal/statement-chief-veterinary-officer-myxomatosis-vaccine Accessed March 1, 2013.
  3. Williams CK, Parer I, Coman BJ, Burley J and Braysher ML. Managing Vertebrate Pests: Rabbits. Bureau of Resource Sciences/CSIRO Division of Wildlife and Ecology, Australian Government Publishing Service, Canberra, 1995. Accessed March 1, 2013.
  4. Walter N. Rabbit myxomatosis – where to now? Proceedings of the Combined Conference of the Unusual and Exotic Pet Veterinarians, Australian Veterinary Association and Association of Avian Veterinarians Australasian Committee, Melbourne, September, 2012.
  5. Marlier D. Vaccination strategies against myxomavirus infections.  Are we really doing the best Tijdschrift voor diergeneeskunde 2010;135(5):194-198.
  6. Nobivac Myxo Data Sheet, MSD Animal Health. http://www.msd-animal-health.co.uk/products_public/nobivac_myxo/090_product_datasheet.aspx Accessed March 1, 2013.
  7. Adams MM, Van Leeuwen BH, Kerr P. Construction and evaluation of live attenuated myxoma virus vaccines with targeted virulence gene deletions. Vaccine 2008;26(46):5843-5854.
  8. Nobivac Myxo-RHD Data Sheet MSD Animal Health. http://www.msd-animal-health.co.uk/products_public/nobivac-myxo-rhd/010_overview.aspx Accessed March 1, 2013.
  9. Spibey N, McCabe VJ, Greenwood NM et al. Novel bivalent vectored vaccine for control of myxomatosis and rabbit haemorrhagic disease.  Veterinary Record 2012;170:309
  10. Adams MM, Van Leeuwen BH, McFadden G, Kerr P. Construction and testing of a novel host range defective myxoma virus vaccine with the M063 gene inactivated that is non-permissive for replication in rabbit cells. Vet Research 2008;39:60.

Bibliography

Fenner F, Fantini B. Biological control of vertebrate pests: The history of myxomatosis, an experiment in evolution.  CABI Publishing, Oxford, 1999.

Fenner F, Ratcliffe FN. Myxomatosis. Cambridge University Press, Cambridge, 2009.

Queensland Rabbit Management Strategy, 2001-2006.http://www.ddmrb.org.au/Files/rabbit_strategy.pdf Accessed March 1, 2013.

NSW Department of Primary Industries, Rabbit Control, October, 2012.http://www.dpi.nsw.gov.au/agriculture/pests-weeds/vertebrate-pests/pest-animals-in-nsw/rabbit-control Accessed March 1, 2013.

Victoria Department of Primary Industries, Rabbits: Using Integrated Rabbit Control, 2007.http://www.dpi.vic.gov.au/agriculture/pests-diseases-and-weeds/pest-animals/lc0298-rabbits-and-their-impact/rabbits-using-integrated-rabbit-control Accessed March 1, 2013.

 

Date of ratification by the AVA Board: 
24 July 2014

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