Rabbit Haemorrhagic Disease

As a profession we all have a duty to promote improvements in animal welfare. Preventative health schemes are key to helping the lives of our patients, and one part of this includes the use of vaccinations.

Posted: 29 May 2019

Rabbit Haemorrhagic Disease

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The most recent PDSA PAW report 2018 highlights the need for this, as currently the level of protection given to pet rabbits in the UK is too low. In the report, we read that;

  • 49% of rabbits haven’t had a primary course of vaccinations
  • 58% of rabbits haven’t had booster injections

It’s interesting to note that whilst many rabbit owners are aware of a need need to get their rabbit vaccinated against Myxomatosis, most aren’t aware of the other major threat, Rabbit Haemorrhagic Disease (RHD), despite the emergence over the last few years of the highly infectious RHD2 variant. The PAW report suggests that the main reasons owners don’t get their rabbits vaccinated are;

  • No animal contact – they feel that since their pet doesn’t come into contact with other animals, then vaccinations aren’t necessary
  • Worried about cost – not surprisingly price is a major deciding factor, but since 87% of rabbits are also not insured, the cost implications are even greater if a pet gets ill

What is Rabbit Haemorrhagic Disease?

RHD is an extremely infectious and often fatal condition that affects both wild and domestic rabbits. There are currently two strains in the UK, RHD1 and RHD2. Both are caused by a Calici virus. RHD1 has been present in the UK since 1992 and RHD2 since 2013.

It’s success as a deadly disease is helped by the fact that it’s easily transmitted. Some of the ways the virus is spread include;

  • Direct contact - with an infected pet or a wild rabbit
  • Fomites, shoes and clothes – animal particles spread via clothes and wind. It’s for this reason that we should warn owners that both garden and house rabbits are at risk
  • Biting insects – the common rabbit flea
  • Faeco-oral route - the droppings of an infected rabbit
  • Contaminated food – fresh hay is a potential problem if contaminated by wild rabbit droppings
  • Litter trays – urine and faeces must be removed
  • Food and water bowls – sharing helps the spread
  • Respiratory route – the Calici virus can be transmitted by inhalation and across ocular and nasal mucus membranes. Sneezing, coughing and close contact can be a problem

RHD2 – the bigger problem

For many years, the original strain of this disease, RHD1, was brought under control by the effective use of vaccines, but as the RHD2 emerged it soon became evident that no protection to the new strain from the original RHD1 vaccine was provided. In just a matter of a few months, the new disease became widespread throughout the UK.

See the distribution of RHD2 in the UK >

Comparing RHD 1 and RHD2

RHD1

The incubation period is very short, sometimes as little as 1-2 days, and unfortunately in many cases, sudden death can occur with no warning. Many vet practices are unaware of a local problem as it develops since owners will often just go ahead and bury the body without asking for help. The virus is also very stable in the environment and can survive for up to 7 months in some situations. It’s also not unusual for it to remain active on clothes and surfaces for at least 3 months.

There are typically three forms of the RHD1 disease

  • Peracute form - animals found dead often within hours of last appearing normal. 
  • Acute form - rabbits appear lethargic, pyrexic and tachypnoeic. These animals usually die within 12 hours. They often appear shocked and collapsed.
  • Subacute form - some rabbits show just mild or subclinical signs. They can go on to recover and become immune to further RHD1 infections.

If you are presented with a case of RHD1, look out for; 

  • Sudden death – a post mortem may reveal acute bleeding, with free blood in the abdomen. The liver will usually be friable and may have a necrotic appearance
  • Haemorrhagic discharges – you may find blood drooling from the nostrils and occasionally from other orifices
  • Haematuria – check for blood in the litter tray
  • Pyrexia – a rectal temperature over 40oC
  • Difficulty breathing – the lungs can fill with blood
  • Lethargy and incoordination – the rabbit will become weak from anaemia

RHD2

This is now the more prevalent disease in the Europe and the UK. All ages of animal are affected, and some breeds seem to be more susceptible than others. The clinical signs of RHD2 are similar to those produced by RHD1 except that they are slower to develop (typically around 5 days). The incubation period for RHD2 is also longer, between 3-9 days, so in these situations the animal will often be infectious to others for much longer compared to RHD1. With RHD2, the mortality rate is much lower, with occasionally around 80% of animals surviving. Survivors of the disease however, tend to have more protracted problems, in particular chronic liver disease. Look for the chronic form of the disease, with animals developing weight loss, jaundice and anorexia. These animals will often be shedding the virus for long periods, as long as 2 months, again helping to spread the disease more successfully.

Vaccinations

As RHD1 and RHD2 are highly contagious, it’s vital we do as much as possible to contain the disease. There are no treatments other than supportive care.

Supportive treatment

With RHD1, the mortality is so high that you’re unlikely to be able to help. However, with RHD2, the longer you can keep an animal supported and alive, the more likely it is to survive.

Spread the word

The good news is that there are some highly effective vaccines available to protect against both RHD1 and RHD2 in the UK, and it’s recommended that all domestic rabbits are immunised from an early age.

In November 2018, the animal health company, Hipra, launched a single-dose vaccine for rabbits. It was the first monovalent vaccine registered in Europe for the prevention of RHD2. The key benefits of the vaccine are;

  • Vaccinations can be given from 30 days of age
  • Immunity lasts 9 months
  • The vaccine is given as a single dose
  • It’s safe to be used in pregnant animals
  • 100% immunity will develop in 1 week
  • Small volume injection – 0.5ml
  • Single doses vials
  • Inactivated vaccine, so there is no risk of infection
  • Available from all major veterinary wholesalers

Biosecurity is essential

As has already been mentioned, the Calici viruses are easily spread, which is why the emergence of these two fatal rabbit diseases has been so successful. Containing the virus is essential, both at home and in the practice. Here are some of our top tips on keeping your rabbit patients safe.

  1. Wash hands - before and after handling all rabbits
  2. Keep rabbits living areas and food bowls clean
  3. Store food and hay in a protective container
  4. Keep rabbits enclosed and secure – prevent wild animals having access
  5. Quarantine – avoid new introductions for at least 14 days
  6. Barrier nursing – essential in practice
  7. Use splash barriers – avoid cross infections from urine, sneezing etc
  8. Use appropriate disinfectants
  9. Use disposable clothing (e.g. gloves, aprons)
  10. No rabbit parties or group vaccinations
  11. One towel use only – wash bedding and handling towels
  12. Educate all staff – make sure everyone understands biosecurity

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