Calicivirus & Myxomatosis

Calicivirus & Myxomatosis are two words that instill fear into pet rabbit owners around Australia & the world. I wanted to have a chat about the viruses, that as a pet rabbit owner you should be aware of. Whether you own a bunny or are thinking of getting one you need to be informed about avoidable risks & precaution to better your chances against deadly viruses present in our community.

Why were the virus’s released?

The long story short – In 1788 the very first European rabbits were introduced to Australia came aboard the first fleet, it was recorded that only 5 rabbits arrived on our shores at this time, subsequently more rabbits were imported by several sources over time in small numbers, adapting rapidly to our environment. By 1940 there was an estimated 600 million rabbits spread across the entirety of mainland Australia & parts of Tasmania. (If you would like to read the full history in detail checkout our History of Rabbits blog)

Rabbit populations were fast overcoming farm land, ravaging native flora, and destroying the natural habitats of our native fauna. The situation was dire.

The Australia Government had to do something to save our land from decimation. Trapping and shooting wasn’t enough to contain the spread & destruction. I am very conscious that some of you may be reading this statement and will be feeling very sad for rabbits – they were only doing what they needed to survive. Man had released them and created a devastating situation. However sensitive this topic maybe it’s important we share information about the history to shed light on why the viruses are in existence today.

First talks & some small trials of using the Myxomatosis virus began from 1920s but at that stage people weren’t fully convinced that the rabbits were a real problem so the introduction was slow – many profited from selling rabbit pelts & meat, it provided a solid income for most during the world war II great depression. As rabbit numbers increase it became undeniably apparent that it was time to ramp up efforts to decrease feral rabbit numbers. They tried introducing Pasteurella from France & the Spanish rabbit flea with little impact, so on Nov 16th 1937 the Australian government officially released the first rabbits infected with Myxomatosis, it was spread by contact from one warren to another though it was soon discovered it travelled further mainly by mosquitos, after a few false starts the virus eventually began to spread wiping out more than half the feral population – reducing it to approximately 100 million allowing Australia’s farming to make a much needed come back. The outbreak lasted around 15 – 20 years before the rabbits began building up natural immunity against the virus strain. Myxomatosis still exists in our community today – however due to it’s waning effectiveness it is no longer actively released by the government. There is no vaccine available for Myxo in Australia (the UK does have one called Myxo Plus RHD). Though it is not as common these days it is still a genuine threat to our pets – especially in areas with increased number of mosquitos.

by 1990s feral rabbit numbers began once again to increase, reaching over an estimated 300 million. Again the government needed to intervene. In 1991 the first vials of the Czech made strain known as RHDV1 (Rabbit Haemorrhagic Disease Virus – 1st strain) were imported into Australia to undergo comprehensive testing.

In 1995 a special station was set up on Wardang Island off the coast of South Australia for testing to be carried out on a controlled group of rabbits. The virus escaped the island by accident and began to spread naturally through the environment via contact & insects, exceeding the expectations of authorities. Permissions to control release the virus around Australia commenced officially in 1996. This is done via baiting food with the virus, infected rabbits spread it to each other by touch and it is also carried by insects such as blow fly’s & mosquitos. The effectiveness of RHDV1 remained strong for sometime and is still very active today, overtime some resistance was being noted especially in young kits so another version of the virus – K5 (Korean made strain) was also introduced in 2017 to top up the prevalence.

Around the same time these viruses were being introduced pet rabbits owners around the world were given access to a developed vaccine. This vaccine named Cylap offered our pets best chance against the RHDV1 & K5 strains ( but not myxomatosis ).

The discovery of RHDV2……

RHDV1 & K5 continued to spread, it was eventually clarified that RHDV1 & K5 can infect young rabbits but does not kill them, and that it results in lifelong immunity in the surviving animals. Many young were still dying but not from those strains, an unexpected occurrence had happened. Suddenly a new, naturally occurring strain was discovered – first noticed in France in 2010, followed by various other countries, later it was detected here in Australia from 2015 onward. This strain we now know as RHDV2 has fast become more prevalent than any other with it having the ability to fatally infect rabbits of all ages & types. Including hares & our pet rabbits.

In present day 2023, RHDV2 is an extreme concern to pet rabbit owners in Australia. An abundance of reported cases are now found in most parts of Australia – To access a location map of potential & confirmed cases of RHDV1, K5, Mxyo & RHDV2 in your area use the Feralscan.org website. These numbers are only from those who choose to have a liver test completed after the death of their beloved pet or rabbits found passed on properties. These recorded numbers can only be presumed as the bare minimum of the actual impact occurring, many people would not reach out for testing.

After multiple attempts to manufacture an updated vaccine on Australian soils protecting against RHDV1, K5 & RHDV2 – they sadly did not pass approval. Other countries such as the UK, New Zealand, parts of Europe & some states in the USA slowly began offering FILAVAC (made in France), 12 monthly injections. ( or with lessor known ERAVAC (made in spain) which only protects against RHDV2 with 9 monthly injections). It wasn’t until June 2022 that Australian pet owners gained access to FILAVAC via import. We are forever thankful to those who never gave up hope for this vaccine and continued pushing our government to allow it.

Note: The Cylap is still currently available the shelf label advises injection once every 12 months for protection against variants RHVD1 & K5 only, 6 – 10 months is an off label recommendation. Australian vets recommend boosters closer together as some ”uncontrolled” studies may have shown increased effectiveness & potential resistance against the newest strain RHDV2 – however we must stress this remains largely inconclusive with many pets being recorded as passing from RHDV2 despite being vaccinated with Cylap twice a year. It is safer to assume that it does not offer ANY coverage against RHDV2 or myxo – your best option is FILAVAC.

Some people get a little nervous about their pet receiving the injections, having a rabbit savvy vet to administer the vaccine is always best practice. Your rabbit can be vaccinated from 4 weeks of age. If your rabbit is receiving it’s very first dose, they’ll be given one small dose with another one or two in weeks to follow. Speak to your vet to devise a plan best suit to your buns needs. Vaccine side effects may include lethargy, fever, digestive upset, nodules or swelling at the vaccination site, typically most rabbits will be less active for 24hrs then be back to themselves, if you are worried about your pet after it’s vaccination please don’t hesitate to reach out to your vet.

The best defenses against Mxyomatosis, RHDV1, K5 & RHDV2 (We must stress again there is NO vaccine COVER AGAINST MXYOMATOSIS in Australia)

• If possible keep your rabbits inside – this is safest and most recommended.
• Use fly mesh or mosquito net on all outdoor housing.
• Vaccinate with FILAVAC every 10 – 12 months. (It can take up to 7 days for the vaccine to be effective so stay on top of your boosters)
• Avoid letting your rabbits roam free at dusk & dawn when insects are most active.
• Wash veggies before feeding and remove any uneaten scraps to limit attracting fly’s.
• Clean litter trays often, rinse with disinfectant.
• Grow plants in your yard with insect deterring qualities like rosemary, lavender, lemon balm, marigold, catnip, basil, citronella
• Ensure wild rabbits cannot enter your yard.
• Avoid contact with other peoples rabbits if you do not know them well.

How do the viruses spread?

Mosquitos, blow fly’s, fleas, rodents & direct contact. It can be transmitted on surfaces, carried into your home on you, by your other pets. If the virus is present in your surrounding areas be mindful of where you walk your dog – land spaces where infected rabbits might be present compose a high risk situation of your dog or self carrying the virus back into your home on their fur or paws, or your shoes.

It’s good practice to remove your shoes before entering your home – have visitors do the same.

Handy Tip* F10 is a pet safe veterinary grade disinfectant which has the ability to kill the virus found on surfaces. It’s available in wipes form, diluted spray or as concentrate. F10 can be used to mop your floors, as a fogger, to spray shoes, clothing, pet housing and equipment for added measure. 10% bleach or 10% sodium hydroxide would also be sufficient if you can not get a hold of F10.

RHDV has been recorded to survive on surfaces for 22-105 days at room temp around 22c degrees, up to 205 days at 3c degrees, 3-7 days at 37c degrees & for up to an hour at 50c degrees.

Symptoms for the viruses vary as followed:

Myxo – your pet will pass within 10-14 days of becoming infected

• Swelling of the skin around the eyes, ears, occasionally the lips and nostrils and the skin around the anus and genital area
• Lethargy
• Disinterest in food
• Fever
• Eye and nasal discharge
• Breathing difficulties

Calici – dependent on the variant your rabbit may show little sign of infection & suddenly pass, the virus slowly attacks the liver and other vital organs. It can take less than 12 – 36 hours or up to 21 days for your pet to pass from the time of infection.

• Bleeding from the nose or eyes
• Lethargy
• Disinterest in food
• Fever
• Weight loss
• Respiratory distress

If you loose a pet rabbit to any of these virus you must not to bring another rabbit into that same environment for as long as 4 – 6 months later to avoid any risks. All surfaces & equipment need to be disinfected. It’s advisable to dispose of any bedding, food & hay immediately that has come into contact with your pet. Sadly due to it’s highly contagious nature it’s very common for the virus to be fatal to all pet rabbits sharing the same space. If you have other separated rabbits in your home it’s vital you quarantine your surviving pet for a full 4 months and be extremely vigilant using biosecurity level measures to avoid them catching the virus.

If you happen to find a stray rabbit, ensure you quarantine the animal away from any of your own pets. Take them to a vet so they can be assessed for the virus. Remember to wash your hands and remove clothing / shoes that may have come in contact with them before re entering your home.

Testing…. what is involved?

If your rabbit suddenly passes away for no apparent reason or from symptoms listed above please consider having your pet tested for virus strains. We understand that the idea of this may seem overwhelming, especially in a time of grief but please find solace in the fact that you could potentially save the lives of other pet rabbits in your home or of those who live within your area. To test, you can take your pet to a vet, they will take a small sample from your rabbits liver and send it to the CSIRO (Commonwealth Scientific and Industrial Research Organisation). If you would prefer to source your own kit you can request a free test kit by emailing rabbitcalicivirus@csiro.au. Whilst you wait for your kit to arrive your pet must be kept frozen. Here in Western Australia the West Australian Rabbit Council can arrange a kit & help obtain a sample from your pet in your home, they are trained in how to help you through the process, are caring & compassionate about the distress you will be feeling upon loosing your pet. They can be reached by emailing testing.warci@gmail.com . Testing results will take 1-2 weeks, you will be emailed the results or you vet will let you know the outcome. All results are also recorded on the Feral Scan Website.

What else can we do?

As a rabbit owner of 6 house rabbits myself i share in the fear of thousands of Aussies that one day i may loose my pets to a virus without a vaccine. At the time of writing the original draft of this blog in 2021, Filvac wasn’t available. Frustration of miss information and our voices being unheard compelled me to keep typing. I wrote it on behalf of those experiencing the painful, unforgivable and avoidable hurt of loosing their pets. I have many close friends who have lost their buns to virus, their stories of seeing their pet in agonizing pain fills my heart with extreme sadness relating first hand to how much i love each of my rabbits. If it was one of any of mine, id be inconsolable. I was seeing sadness daily, across socials more and more people suffering from the grief of sudden loss. I had so much understanding surrounding the need to control the wild population and the history behind the introduction of the viruses but the one thing i couldn’t comprehend was why our Aussie pet rabbits were overlooked for the opportunity to vaccinate – being the 3rd most popular pet within Australia. I couldn’t imagine the same lack luster approach if these viruses affected our cats or dogs as a rabbit owner / animal lover i considered them equal and know most would the same. Without the continuous noise from Australian pet rabbit owners, and with special mention to The West Australian Rabbit Council, and our rabbit rescue groups our government would not have approved it. Too all of you, i thankyou from the bottom of my heart.

All we can do know is promote and educate about vaccine options, share knowledge and offer advice about protection via husbandry – Its important to keep the stories of the pets we have lost alive and support each other in the rabbit community. Though the past is muddled with sadness, look at what we have achieved together for the love of these beautiful creatures.

It’s with understanding this topic can evoke an emotional response, i urge everyone to remain respectful when reaching out to educate. If you meet someone who’s learning about caring for their bun remember we all started off the same way.

Though it can be emotionally confronting, sharing the death of your pet rabbit to raise awareness in the community can help spread the word far and wide potentially saving others. We will stand with you. Be brave for everybun and get your pets tested if they pass suddenly or with symptoms. Using the hashtags #itsnotjustarabbit #filavacaustralia #rabbitsaustralia can help get our topics to keep trending online.

If you have lost a beloved pet and want to share their memory or you live in fear of the virus strains please leave comments on this page to express how you feel, i will publish your concerns and memories for all to read.

Thankyou for taking the time to read my blog, please share it far & wide. If i can help you with further information reach out to me anytime info@smooshiefacetreats.com.au

Big Love Holly xx Smooshie Face HQ

https://minister.awe.gov.au/littleproud – The Minister of Agriculture in Australia is Mr David Littleproud

Other Useful Links

https://www.feralscan.org.au/rabbitscan/map.aspx?mapMode=rhdv – Virus Tracking Australia

https://research.csiro.au/rhdv/testing/ – Commonwealth Scientific and Industrial Research Organisation