The New Rabbit Disease

Written by Kerry Greener

Last Edited 8th August 2016

Finally Get Real Answers to RHDV-2

Deadly New Strain Rabbit Disease Causing Widespread Panic

Rabbit breeders are familiar with rabbit haemorrhagic disease (RHD) but a new strain of the virus (RHDV-2) is resistant to the typical RHDV vaccine.Rabbit breeders are familiar with rabbit haemorrhagic disease (RHD) but a new strain of the virus (RHDV-2) is resistant to the typical RHDV vaccine.

Recent stories in the National Press about a new strain of rabbit haemorrhagic disease (RHD), that kills pet rabbits within days, and has no UK vaccine, is sending widespread panic across Great Britain’s domestic rabbit owners.

There has been an increase in cases of RHD in rabbits that have already been vaccinated, and a new variant of RHD is believed to be responsible.

Most breeders have been familiar rabbit haemorrhagic disease, otherwise known as RHD, but this new variety, that is being identified as RHD-2, is a new strain and is resistant to the typical RHD vaccine.

This is proving a severe and worrying problem in rescue centres and veterinary surgeries and with rabbit breeders and rabbit enthusiasts all over the UK.

Unreported Truth

Death Toll
It has been reported that over 400 rabbits in Britain have succumbed to this new killer strain in the last six months.

The deadly virus, which has almost no symptoms, may have affected 2,000 rabbits already, with a further 1.3 million unprotected pets at risk right now, but the reality is that the death toll may be 10 times higher due to owners not reporting the deaths.

What is RHD?

The image shows atomic model of the highly infectious and fatal RHD calicivirus - 'Calic' referring to the cup-shaped depressions on the surface of the virus.

Rabbit haemorrhagic disease (RHD) is a highly infectious and fatal disease which affects wild and domestic rabbits. RHD only affects European rabbits (Oryctolagus cuniculus). It does not affect other lagomorphs, such as cottontails, or other small mammals, such as chinchillas, guinea pigs, rats and mice.

This calicivirus (calic meaning 'cup' or 'goblet', thus named from the cup-shaped depressions on the surface of the viruses), was first identified by the characteristic haemorrhages found around the internal organs of the rabbit’s body and it the disease was named ‘viral haemorrhagic disease’ (VHD) or rabbit haemorrhagic disease (RHD), with the latter becoming the standard term in recent years. The acronym RHDV (rabbit haemorrhagic disease virus) is used to describe the virus.

RHD is a universally recognised cause of sudden death in rabbits however vaccination has proved to be an effective control so far and the original strain of RHD although reaching endemic proportions in the UK, was brought under relative control from the 1990s.

History & Spread of RHD

The disease then spread to Korea by the rabbit fur industry and subsequently spread to other countries in Asia.

By 1986 RHD had reached Italy and by 1988, it was reported in many countries worldwide, probably introduced and spread by rabbit meat trading.

The wild rabbit population managed to avoid the disease until the early 90s where is was reported that hundreds of wild rabbits on the Scandinavian island of Gotland were seen dead in the fields and many more were discovered dead in their burrows. They were on the verge of extinction in only one week.

A tagged wild rabbit deliberately infected with the RHDV - It was only a matter of time before the dealy virus spread worldwide.A tagged wild rabbit deliberately infected with the RHDV - It was only a matter of time before the dealy virus spread worldwide.

In the UK the first outbreaks of RHD were recorded 1994.

Sadly, in 1997, an insane attempt to biologically control the wild rabbit population on Wardang Island in Australia went disastrously wrong, and the infection spread to the mainland, where it killed millions of wild rabbits and domestic rabbits, and has subsequently meant the enforcement of strict laws governing the ownership of pet rabbits in most Australian territories.

Unfortunately, it was only a matter of time before the infection was surreptitiously introduced into New Zealand.

The first confirmed case in the United States occurred in 2000 in a small breeding colony of exhibition rabbits in Iowa. Twenty-five of the 27 rabbits died with no indication of the source of infection.

New Variant Discovery

The new rabbit disease, RHDV2 has the potential to devastate a wild rabbit population and can also infect previously vaccinated pet rabbits. Unlike RHDV1, it also appears to affect hares.The new rabbit disease (RHDV2) has the potential to devastate a wild rabbit population and can infect previously vaccinated pet rabbits. Unlike RHDV1, it also affects hares.

In 2010, an uncharacteristic outbreak of RHD occurred in a rabbitry in France in which 25% of rabbits which were vaccinated against normal RHDV died. An emergency vaccination was administered to the remaining rabbits which stopped the mortalities, but it was slower than the usual 7 to 9 days and took much longer to control, taking up to 15 days in most cases.

The wild rabbit population was also affected the same way. Samples were genetically analysed and found the virus causing the fatalities was related to, but highly distinct from, the strains of RHD isolated from previous outbreaks.

This new strain of infection has the potential to devastate a wild rabbit population and can also infect previously vaccinated pet rabbits and unlike RHDV, it also appears to affect hares. This variant was renamed RHD-2, and the virus itself as RHDV-2.

The Invasive Animals CRC national rabbit biocontrol monitoring program has confirmed through laboratory testing that Rabbit Haemorrhagic Disease Virus 2 (RHDV2) was present in three recently deceased European brown hares in Australia – one in Victoria and two in South Australia.

RHDV2 is specific to Lagomorph species, which include rabbits and hares. Australia only has two Lagomorph species – the European rabbit and the European brown hare. In Australia, RHDV2 has now been confirmed in these two invasive Lagomorph species, and has not been found to infect or kill any native or other introduced species. In Europe, RHDV2 has infected European rabbits, Cape hares and Italian hares, and similarly has not infected or killed any other native or introduced species.

By 2011, this RHD-2 was identified in Italy and then it was detected in the UK in 2013, although retrospective sample examinations from previous years suggests it has been present since 2010.

Understanding RHDV - Characteristics

The RHD calicivirus has a preference for liver cells and replicates in the liquid found inside these cells. It is a flesh-eating liver disease, which causes the death of most cells and tissue.'Gross' examination is a pathology inspection process with the naked eye to obtain diagnostic information.

The RHD calicivirus has a preference for liver cells and replicates in the liquid found inside these cells. It is essentially a flesh-eating liver disease, which causes the death of most or all of the cells and tissue of the spleen.

RHD is usually diagnosed at post-mortem (an examination, or autopsy of a corpse in order to determine cause of death). It is suspected as the cause of any sudden death, especially if more than one rabbit in the household has died in the same way.

Death is due to disseminated intravascular coagulopathy or liver failure. Disseminated intravascular coagulation, (otherwise known as DIC which is a pathological process characterized by the widespread activation of the ‘clotting cascade’ - a complex set of negative feedback mechanisms used by the human body as a means of maintaining blood haemostasis - a process which causes bleeding to stop), that results in the formation of blood clots in the small blood vessels throughout the body in small blood vessels in most organs, notably the lungs, heart and kidneys, resulting in fatal haemorrhages.

Three manifestations of the RHD infection may be seen:

  1. Peracute - animals are found dead within hours of eating and behaving normally.

  2. Acute - affected rabbits show signs of lethargy, raised body temperature (above 40°C) and increased respiratory rate. These animals usually die within 12 hours. Blood samples show a reduction in the number of white cells and platelets in the blood, fibrin thrombi (an insoluble protein that is essential to clotting of blood) and markedly raised liver enzymes. A main feature of the disease is a dramatic drop in blood pressure that makes it difficult to find a vein to take blood samples or set up intravenous fluids. There is usually blood in the urine and haemorrhagic vaginal discharges and sometimes a foamy fluid filtered from the circulatory system can be seen coming from the nostrils. Small localized areas of dead tissue resulting from failure of blood supply can occur in the brain and occasionally convulsions or other neurological signs are seen just before death. Dying rabbits are pallid, shocked and collapsed. A rabbit will rarely recover from the acute phase and if they do they generally develop jaundice and die a few days later. A rabbit can very occasionally survive this period, but with permanent liver damage.

  3. Subacute - Rabbits showing mild or subclinical signs from which they recover and become immune to infection.

Understanding RHDV -  Transmission

It is believed rabbits that recover from RHD are potentially infectious to other rabbits for one month. It is not known how long the period is for RHDV-2.RHDV is difficult to kill and can survive harsh environmental conditions. It can also survive inside rabbit carcases for months.

RHD has a short incubation period of one to four days. The virus replicates in many tissues, including the lung, liver and spleen, with consequential viremia, (where the virus enters the bloodstream and then has access to the rest of the body) and then subsequent haemorrhage.

RHDV is difficult to kill and can survive harsh environmental conditions. It can survive temperatures of 50°C for up to an hour and is not inactivated by freezing. The virus can also survive in the environment and inside rabbit carcases for months. Carcases from wild rabbits that died from RHD can be a source of infection, by spreading the virus via the faeces of scavengers.

Infection is easily transmitted between infected rabbits by the oral, nasal or conjunctival routes, with the digestive system and respiratory tract as the main portals. Food bowls and bedding can also transmit infection. Only a few virions are required to produce infection.

It is believed rabbits that recover from RHD are potentially infectious to other rabbits for one month. It is not known how long the period is for RHDV-2.

Natural Immunity

Age immunity does not occur with RHDV-2 and both young and nursing kits are prone to infection.Most rabbits younger than four weeks remain unaffected by RHD and develop a lifelong immunity, if exposed to the disease.

After the initial outbreak in China in 1984, later testing in rabbits exposed to RHDV showed antibodies to the virus in serum collected before the breakout in 1984.

It was therefore suggested that non-pathogenic strains of RHDV could have protected rabbits by stimulating antibody production, and in 1996, a non-pathogenic calicivirus was recovered from breeding rabbits in Italy that protected them against RHD. Subsequent investigations in Australia and the UK revealed the presence of non-pathogenic strains of calicivirus that may confer some immunity to RHD.

Most rabbits younger than four weeks remain unaffected by RHD and develop a lifelong immunity, if exposed to the disease. Unexposed rabbits become increasingly susceptible until 6 to 10 weeks old, when physiological resistance to the virus disappears. This resistance appears to be due to a rapid and effective inflammatory response by the liver, with a continued boost in white blood cells around the sites of infection.

However, this age immunity does not occur with RHDV-2 and both young and nursing kits are prone to infection. In fact, it can affect rabbits of any age but it has also been reported the variant gives rise to lower mortalities than classic RHD, although these reports are not conclusive.

What we do know is there appears to be a longer and more variable incubation period (three to nine days) and a more prolonged period of illness prior to death (up to five days).

What is RHD-2?

Less contagious than RHDV, RHDV-2 is more difficult to diagnose in the early stages, meaning rabbits can carry the disease for a longer and also have no outward visible signs of infection.RHDV-2 is difficult to diagnose - rabbits can carry the disease for longer and have no visible signs of infection.

Since the discovery of RHD, variants of the virus have emerged and have been named RHDVa and RHDVb. Non-pathogenic strains of the calicivirus have also been found. (Ones that don’t develop into disease).

The RHDVb variant has been recently shown to differ from RHDV in many characteristics, so the virus was renamed RHDV-2. There is an opinion this is a new virus, which is a different serotype (or serovar, meaning there is a distinct variation within this species of bacteria) from RHD.

The term ‘lagovirus’ encompasses all types of RHDV and its variants.

The RHD-2 virus variant appears to be replacing the classic RHDV in continental Europe and now Britain. Although believed to be less contagious than RHDV, RHD-2 is more difficult to diagnose in the early stages, meaning rabbits can carry the disease for a longer.

Subacute or chronic infections were more frequent and more rabbits survived, showing a more protracted disease with weight loss and jaundice.

Where is RHD-2 Now?

RHD-2 spreads the same way as RHD, especially with infected animals, through biting insects, flies, other animals, bedding and foodstuffs.RHD-2 spreads the same way as RHD, especially with infected animals, through biting insects, flies, other animals, bedding and foodstuffs.

RHD-2 is believed to have spread through domestic and wild rabbits in continental Europe, where rabbit farming is significantly more prevalent than in Britain, however since March 2016, RHD-2 has been recorded across Cheshire, Devon, Leicestershire, Shropshire, Worcestershire, Leeds and Moray. 

It is believed that Devon and Cornwall have the most reported deaths.

How is this New Rabbit Disease Spread?

RHD-2 spreads the same way as RHD, through people who have come in to contact with infected animals, through biting insects, flies, other animals, bedding and foodstuffs.  

Higher temperatures are also said to help spread the disease.

RHDV-2 Symptoms & Signs

Neill Gardner, chairman of the BRC said a number of vets were also unaware of RHDV2, or didn't deem it necessary to vaccinate pet rabbits often underestimating 'the worth' of the rabbit.Neill Gardner, chairman of the BRC on the right in the image above, said a number of vets were also unaware, or didn't deem it necessary to vaccinate rabbits against RHDV2.

Neill Gardner, chairman of the BRC (British Rabbit Council) said,

“The biggest worry about this virus is that it is endemic and spreads slower than it kills so it creeps around the country in a more sinister pattern than the first strain.” 

Neill added that lack of knowledge of RHD-2 was also a major problem,

“The vast majority of owners don’t know about it.”  

He added that the disease was spreading in the warmer weather and,

“Unfortunately, a lot of vets are still saying they have never seen it or that they don’t see it as necessary to vaccinate as they often underestimate the worth of the rabbit.”

In a recent interview with the BBC, Neill worryingly said,

“The fear factor is we don't know how it's spreading, with the former strain there was usually a visible sign, like bloody discharge from the nostrils, now they just drop dead”. 

Recent Reports About RHDV-2

Peter Smith and his daughter Claudia, rabbit breeders based in Morpeth, Northumberland, UK lost 10 of their rabbits within three days in September 2015 to RHDV2.Claudia & her father Peter Smith, rabbit breeders based in Morpeth, Northumberland, UK, lost 10 rabbits within 3 days in September 2015 to the new RHD-2 virus.

Vaccines are easily accessible for the original virus RHD, however, Hazel Elliott, a member of the British Rabbit Council's governing body, said European vaccine firms were applying for licences in the UK, but was unclear as to when they get them. She also said she was aware of three British breeders who had lost more than 100 rabbits in the past six months.

Peter Smith and his daughter Claudia, 15, from Morpeth, Northumberland, lost 10 of their rabbits within three days in September 2015.

Mr Smith said,

“There were no outward signs whatsoever,” he said.

“I was in the kitchen, which isn’t too far from where our rabbits are kept, and I heard an almighty squeal. We rushed out and one of the rabbits was dead.”

Mr Smith, who keeps up to 50 rabbits at a time and takes them to shows, also said there was no pattern to the deaths, with both babies and adults affected alike.

Recent Reports on RHDV2

Richard Saunders, a Rabbit Welfare Association and Fund veterinary expert, said the 'vast majority' of owners didn't know about RHDV2, which does nothing to help awareness and disease control.Richard Saunders, a Rabbit Welfare Association & Fund veterinary expert, said the 'vast majority' of owners didn't know about the RHDV2 virus.

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Sources reveal that at least one pharmaceutical company has produced a new RHDV-2 vaccine but Richard Saunders, a Rabbit Welfare Association and Fund veterinary expert and advisor, said about 1.3 million unprotected rabbits were still at risk in the UK, with the only vaccines that work having to be imported from France and Spain, however he also revealed that the vaccine is expected to soon be licensed in the UK.

For more information about rabbit diseases, see Harcourt-Brown and the World Organisation for Animal Health.

Latest News on RHDV2 Vaccine

Richard Saunders, as introduced above, now reports that the RWAF has been assessing the disease risk of RHD-2 and the subsequent need to import a vaccine effective against the new variant disease.

He is pleased to account that the RWAF has now successfully established a special import certificate for a suitable EU member state vaccine and placed an order for a small number of vaccines to establish an ordering system into the UK.

A joint vaccine against RHD1 and RHD2 was available from the middle of June 2016 and can be ordered via your veterinary practice.

Filavie, a vaccine manufacturer in France, will be supplying NVS (National Veterinary Services Ltd), a veterinary wholesalers in the UK with the Filavac vaccine.

Filavac RHDV2 Vaccination Protocol & Ongoing Care

The licensed vaccination protocol for Filavac RHD / RHD-2 is two injections three weeks apart, with annual revaccination advised.

The effect of one injection only has not been investigated.

As with any vaccine not licensed for simultaneous administration, an interval of two weeks between this and other vaccines is advised.

This new vaccine protects against RHD and RHD-2, but not against myxomatosis; therefore, it does not replace the use of Nobivac RHD-Myxo.

It is also possible exposure to lagoviruses from the wild rabbit population is advantageous for a healthy, vaccinated pet rabbit; it may develop a stronger immunity if challenged. Not all lagoviruses are pathogenic, so natural exposure could be protective.

Important Filavac Vaccination Protocol:

Please only go through your vets, and ask them to look out for RWAF updates before calling the NVS.

Your vets will need their own license, but obtaining the vaccine is not as simple as writing a prescription so your vet may not see enough rabbits for this to be a practical or viable option for them.

Standard advice with immunological products not licensed for simultaneous administration is to space them out by at least 2 weeks.

The manufacturer of Filavac advised to administer a single dose of the vaccine, followed by annual boosters in low risk situations, and 6 monthly in the case of breeding does at high risk.

In the UK, it is suggested that 'high risk' situations include rescue centres, any geographical location where cases have been reported recently, and breeders, unless they have a strict quarantine policy.

The manufacturers of the Filavac product suggest that vaccination can be at the same time as the Nobivac Myxo-RHD, as long as it is not in the same site or the same syringe.The manufacturers of the Filavac product suggest that vaccination can be at the same time as the Nobivac Myxo-RHD, as long as it is not in the same site or the same syringe.

Generalised supportive care is being advised for rabbits that survive RHD2, including fluid therapy, syringe feeding and warmth, but bear in mind these rabbits can be infectious to others so barrier nursing is vital.

Gratitude & Thanks

The Just Rabbits community is enormously grateful to the wonderful Vet Dr. Richard Saunders for doing the necessary research and negotiations with the vaccine manufacturer.

Dr. Saunders worked tirelessly arranging the necessary import paperwork and liaising with the National Veterinary Services in order for them to be able to supply the new vaccine to everyone waiting and in desperate need.

On behalf of all of us, and all our relieved bunnies everywhere, we thank you from the bottom of our rabbit loving hearts!

For a more detailed look at all aspects of bunny health, diet, environment, companionship & longevity check out the revolutionary iRabbit READY System by Kerry Greener of Just Rabbits Limited

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If you are worried, or concerned about any aspect of your rabbit's health, or RHD and RHD2, then tell us your story and we will publish a dedicated page on your behalf where other readers can respond with their experience and help with suggestions and input to put your mind at rest.

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If you are worried, or concerned about any aspect of your rabbit's health, or RHD and RHD2, then tell us your story!Concerned about RHD2 or any aspect of bunny health? Tell us your story and we'll publish a dedicated page on your behalf.

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Mystery Rabbit Deaths - Is it RHD-2? 
Hi there, Just this Thursday morning before school I went out to see my three rabbits, they were all acting fine and showed no symptoms of illness. …

Tragic Loss of Rabbits - Possible RHD-2 
We bought 2 six week old mini lops 5 months ago for my daughter's 9th birthday. Ginger was poorly on Monday, and we got an emergency appointment at …

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