What are Calcivirus?
This disease is highly infectious and although signs may include fever, bleeding from the nose, and lethargy, many rabbits who are infected display no signs and die suddenly.
Unfortunately, there is no cure for this disease, however infected rabbits can be offered supportive treatment. Prevention is an essential aspect in the management of this condition, an effective vaccination against this disease is available and should be discussed with your veterinarian.
Rabbit calicivirus, also known as viral hemorrhagic disease, is a reportable disease in some parts of the world. This highly infectious disease was first reported in 1984 in the People's Republic of China, from here it was spread to Mexico City in 1998, however was considered eradicated by 1992. Another outbreak, following a laboratory incident in Australia occurred in 1995 which lead to the virus being released, killing millions of rabbits within two months and spreading to the USA. Currently, the USA is considered disease free, although the virus is reported across Australia and New Zealand.
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Symptoms of Calcivirus in Rabbits
Rabbit calicivirus is a highly infectious and often swift acting disease. Symptoms of mild cases are often depression and loss of appetite. Rarely, rabbits recover from this disease after experiencing these symptoms and go on to have immunity against re-infection.
In more common peracute forms of this disease, the rabbit may experience rapid deterioration with a fever developing following infection, an onset of seizures, fevers, and coma, leading to death within 12-36 hours of symptom onset.
Some rabbits may go on to experience other symptoms such as swelling of the eyelids, bleeding from eyes, and paddling. Respiratory signs may develop such as cyanosis. For these rabbits, unfortunately the disease often progresses to a fatal stage within a few weeks of infection. For many rabbits the only sign is unexpected, sudden death.
- Loss of appetite
- Respiratory signs
- Blue mucous membranes
Causes of Calcivirus in Rabbits
The origins of calicivirus are not completely understood, but it is known that the condition is caused by the RHDV virus, a member of the genus Lagovirus and family Caliciviridae.
Calicivirus is transmitted through the oral, nasal and conjunctival pathways after the rabbit comes into contact with an infected animal, object or organism. This virus is shed through the urine, feces and respiratory secretions and is often spread between rabbits on carriers such as flies, fleas, mosquitoes and other rabbits. The virus may also be carried on contaminated items such as clothing, food, bedding or water, highlighting the importance of strict isolation if a case is suspected. This disease is endemic in both New Zealand and Australia.
Diagnosis of Calcivirus in Rabbits
Your veterinarian will examine your rabbit carefully. Often with this disease the diagnosis is made by considering your pet’s symptoms and other history such as vaccination status and exposure to sick pets, or rabbits who have died suddenly. Your veterinarian may also perform diagnostic tests to rule out other similarly presenting conditions such as:
- Heat exhaustion
- Septicemic pasteurellosis
In post-mortem investigations, pets suffering from this disease are commonly seen with hemorrhagic lesions and congestion of the liver, lungs, heart and other organs.
Treatment of Calcivirus in Rabbits
Unfortunately, there is no known treatment for this disease in rabbits. Your rabbit may be treated symptomatically with intravenous fluid therapy, syringe feeding, and analgesia, but because this disease often causes internal hemorrhages the prognosis is poor. Your veterinarian may discuss euthanasia on humane grounds as the best option for your pet.
As the virus can live in the environment for up to seven months, if you suspect an infection has occurred it is vital that the area is thoroughly disinfected using an effective solution.
Recovery of Calcivirus in Rabbits
The most effective way to protect your pet against this disease is to have him vaccinated annually for this disease. Other steps you can take to protect your rabbit are:
- Keep your rabbits housed indoors and rabbit-proof your environment to ensure wild rabbits are unable to gain access to your backyard
- Maintain excellent personal hygiene – wash your hands thoroughly after coming home, especially if you have been in contact with other people who own rabbits or places where rabbits may have been
- Wash your hands prior to handling your pet
- If you come into contact with other rabbits thoroughly disinfect your clothing
- When introducing new cage mates place the rabbit in quarantine for 5 days, ensuring strict isolation protocols are in place
- Control insects such as flies
- Provide regular flea treatment to reduce the chance of infection spread from parasites
- Following an infection disinfect thoroughly with 10% household bleach, 10% sodium hydroxide or 1-2% formalin