This is part 1 of 2 in our series regarding viral diseases in rabbits in Australia. It’s important for you to know all you can about Rabbit calicivirus as your rabbits and clients need to know everything.
The two part series will cover:
1. Calicivirus – Rabbit Haemorrhagic Disease Virus (RHDV)
Calicivirus is a viral disease that is present in multiple strains in Australia.
RHDV 1 – The original virus released in 1996
RHDV 1A – A strain found in Sydney in 2014
RHDV K5 – Korean strain – Released in March 2017
RHDV 2 – Detected in Canberra in 2015
So what is Rabbit Calicivirus?
Rabbit Haemorrhagic Disease Virus (RHDV), or Rabbit Calicivirus, is a lagovirus, which is highly contagious and has a mortality rate of 40-100%. It was selected and tested to be used for wild rabbit population control in the 90’s. It was accidentally released during testing in 1996.
However, the accidental release was very effective and is now well established in Australia.
This has increased the chance of your rabbit patients being exposed. Our best defense is dependent on cross-protection and off label usage of Cylap – only being on-label for protection of RHDV1.
RHDV is very contagious and there is no treatment
Its worth saying again, there is no cure for calicivirus!
Clinical signs and transmission
The clinical signs of calicivirus include; diarrhoea, nasal/ocular discharge, inappetance, lethargy, pyrexia, seizures, restlessness and diarrhoea. Unfortunately, death can occur 1-2 days after infection.
Mainly young rabbits are at risk of infection, though if you have an unvaccinated rabbit, who frequents those seedy wild burrows late on a hot mosquito filled summer’s night, then he is obviously at risk too.
Calicivirus is spread by direct contact with infected rabbits, or indirectly by infectious secretions or urine and faeces on grass, equipment, clothing or via biting insects such as mosquitoes, flies and fleas.
Young three and four week old rabbits and unvaccinated rabbits are at the highest risk of infection. so if you see a young rabbit in a consult, it may be worth adding in an off label 8 week vaccination to the 12 and 16 week vaccinations.
Regarding vaccinations, there is a vaccination against RHDV 1. The Cylap vaccination is available, and is labelled for vaccinations of kits at three and four months old, then annually.
Due to current concerns, the Cylap vaccination is often given every 6 months to prevent infection, if you have a high risk traveling bunny, or are very cautious, then this is wise. Otherwise there is not yet proof that this reduces risk of infection
Our other main method of prevention is via reducing exposure of our rabbits to RHDV.
How can we do that? Apart from having our vaccination shield up, we can use our understanding of calicivirus to protect our bunnies. We can achieve this by:
1. Reducing exposure to wild rabbits
2. Reducing fomite spread of the virus by washing your hands thoroughly prior to handling your rabbits
3. Mosquito and fly proofing hutches
So first, your pet rabbits probably don’t spend too much time with wild rabbits. It is however worthwhile checking your yard for holes in your fences, and burrows. Additionally you can further reduce risk by not feeding your rabbits fresh grass
Secondly you can reduce the spread of the virus via fomites by thoroughly washing your hands prior to handling your rabbits. If you are very suspicious you have handled infectious rabbits or materials, then you should wash your hands in 10% bleach, or 10% trigene mixed with water. Any new equipment or toys for your bunnies should also be cleaned using these mixtures. if you are introducing a new rabbit into the house/hutch, it may be worth quarantining the new bunny for up to one month prior to introducing them to your new rabbits. And not acquiring lethargic bunnies with ocular and nasal discharge!
The third way to minimize exposure is to insect proof your rabbit enclosure! This can be achieved with mosquito / fly netting or fine mesh. Additionally if your rabbits play outside, minimize the time spent outside during dawn and dusk, as this is when mosquitoes are most active.
Fleas are also biting insects that can carry RHDV, so if you notice fleas on your rabbit, you can use a suitable veterinary approved flea prevention treatment. Revolution and advantage are good on label options here, you can find the doses here:
You will need a password to access this content, and you must be a vet! Email us at email@example.com to get the password!
It’s important to protect our rabbits against this disease! Make sure you recommend vaccinations to your rabbit clients!
Next week we will cover part 2 in our series, myxomatosis! Stay tuned!
Inner South Vets. Rabbit Vaccination. http://www.innersouthvets.com.au/blog/rabbit-vaccination/
AVA. Rabbit Calicivirus in Australia. http://www.ava.com.au/rabbit-calicivirus
RSPCA. What is rabbit calicivirus and how do i protect my rabbit from rabbit haemorrhagic disease. http://kb.rspca.org.au/what-is-rabbit-calicivirus-and-how-do-i-protect-my-rabbit-from-rabbit-haemorrhagic-disease_630.html
Melbourne Rabbit Clinic. Calicivirus RHDV Portal. http://www.melbournerabbitclinic.com/veterinary-information-portal/calicivirus-rhdv-portal/