Update On The Rabbit Calicivirus Outbreak

Update 2017: What rabbit owners need to know about the planned release of the K5 calicivirus strain

To those who love rabbits it’s been a tough week.

One week ago we were notified that the new strain of Rabbit Hemorrhagic Disease Virus called RHDV2 had reached South Australia and was causing deaths around Adelaide.

We posted an alert on our Facebook page, and only then did the true horror of what was happening become clear.

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*Alert to Rabbit Owners*A new strain of rabbit calicivirus is spreading quickly through the country and is now being…

Posted by Walkerville Vet on Thursday, February 25, 2016

Pet rabbits are dying in yards far from other rabbits, and losses by commercial breeders are high. Most owners had no idea their rabbit was one of many casualties and that there was a silent mass epidemic underway. The Facebook comments make for tragic reading.Rabbit calicivirus map

Could these just be random deaths? Here’s why that’s unlikely:

  • So many deaths all at once are not a normal pattern.
  • Local researchers have proven that RHDV2 is now causing deaths (that’s their map above) around the edges of Adelaide.
  • Thanks to one of our clients we now have the proof that the virus is killing rabbits in the very heart of the

Roger died suddenly in the Adelaide CBD last weekend and his owners kindly donated their beloved rabbit for testing.

The tests have confirmed that he died of RHDV2 infection. That’s in a courtyard in the middle of a city. If he could get it, every rabbit is at risk.

In the same batch of testing were three other rabbits from Adelaide and the hills also positive for RHDV2.

roger calici rabbit
Roger a few days earlier

Bearing in mind how few rabbit deaths are being thoroughly investigated, we think the majority of these unexplained deaths are due to the new calicivirus.

How To Prevent Calicivirus Infection

There are no guarantees, but here is what we recommend to reduce the risk:

No access to gardens or garden clippings

The virus is probably being spread by flies leaving droppings and spots on foodstuff and housing. Keep your bunny inside and only feed commercially grown hay, pellets and veggies. Commercial foods can still be contaminated but the risk will be lower. For example, current hay for sale may have been made before this outbreak began.

Insect control

Don’t allow flies to come into contact with your rabbit. Being inside should be protective, but if they have an outside hutch, invest in some flymesh and attach it.

Hanging insecticidal pest strips nearby is another good idea but read directions carefully as these can be toxic if too close.

Choose a product from our list of registered parasite treatments for your rabbit.


Although less effective, we think the vaccine is still very helpful.

It has been recommended to vaccinate kits at 4 weeks, then at 8 weeks, and again at 12 weeks or later, followed by six-monthly vaccination. Read our veterinary association guidelines.

However, protection has been disappointing and deaths have occurred in vaccinated rabbits. Therefore, we have reverted to the vaccine manufacturer’s guidelines of annual vaccination. 

Vaccination should still give protection against classic RHDV and RHDVa strains like K5.

Where Did RHDV2 Come From?

The virus appeared overseas around five years ago, but was first reported in Australia in 2015. It was not deliberately released by Australian authorities. The fact that it probably came here by itself says a lot about how easily RHDV2 can spread.

What Are The Symptoms Of Rabbit Calicivirus?

The virus acts extremely quickly, and so in most cases no signs of illness are seen before death.

When seen, signs include lethargy, not eating or a soft mucous dropping. Sometimes at the time of death blood is seen around the nostrils (hence the disease name) but this is not a reliable indicator.

The presence of more than one sudden death is very suspicious but only laboratory testing can confirm the diagnosis.

What Else Causes Sudden Death In Rabbits?

The most common non-viral cause is Gastrointestinal Stasis, a nasty bacterial enterocolitis usually seen in rabbits on low fibre diets.

Fox attack in city rabbits is a lot more common than people realise.

Myxomatosis causes a prolonged disease with conjunctivitis and swelling of the eyelids, and survivors having swellings on the body called myxomas. Read all about myxomatosis here.

If your rabbit seems quiet, unwell or off food, get them checked by a vet ASAP. All is not lost.

Does Rabbit Calicivirus Affect Other Animals?

Dogs, Cats, Guinea Pigs, Horses, Chickens and other animals are all safe. The original Czech strain of RHDV and mutated varieties only affected rabbits. It is suspected that RHDV2 can also affect the European Hare.

Other species have their own calicivirus (for example, one of the cat flu viruses!) but like most viruses they don’t easily cross species barriers.

Why Is This Calicivirus Outbreak So Bad?

Speed Of Spread.

This virus behaves very differently in Australia to how it behaved in other countries. Instead of normal slow geographical spread it has leapt and jumped hundreds of kilometres a day.

Researchers here in South Australia have discovered that it is being spread by flies.

Less Vaccination

In 1996, botched though it was, the original RHDV was scheduled for a planned release before it escaped. That gave manufacturers the time to develop a vaccine. The subsequent media interest made rabbit owners rush to get their bunnies protected, and it worked. I don’t recall a single fatality in a pet rabbit during the initial outbreak.

This is the same vaccine we’ve used since and it’s done a good job. However, we think only a low percentage of rabbits are up to date with their vaccinations today. That allows the virus to jump from rabbit to rabbit even in urban areas.

Lack Of Awareness

The lack of publicity about this outbreak has also meant that we have been caught by surprise. If there had been more of a hue and cry we could have got the rabbits protected before the virus hit.

Possibly the successful prevention of serious problems in 1996 tricked us into underestimating the virus this time.

Reduced Vaccine Efficacy

This virus has only 85% similarity to the 1996 Czech strain. Researchers agree that the vaccine should still offer some protection, but it will neither be as effective or as long-lasting as before. Vaccinated rabbits are also dying.

Are Other States Affected?

Yes, it is certainly being seen in Victoria and New South Wales, although it does not appear to have hit Sydney and Melbourne yet like it has in Adelaide.  Here is the most recent RHDV2 map we know of for New South Wales.

We are lucky to have a specialised team of RHD researchers here which has sped up identification of the problem.

To those who see rabbits only as an agricultural and environmental problem we ask for your compassion for the large numbers of pet rabbit owners. These rabbits and their owners aren’t part of the problem.

So, are we beating this up? Nothing would make me happier than to be proved wrong but all my instincts tell me we’re in the middle of something big, unprecedented and tragic.

By Andrew Spanner BVSc(Hons) MVetStud, a vet in Adelaide, Australia. These blogs are from a series regularly posted on Facebook and Twitter. Like or follow our page or subscribe via email to read the latest.

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