Rabbit hemorrhagic disease virus is a highly contagious and deadly disease that affects rabbits only. It was first recorded in China in 1984, but has since traveled to over 40 countries around the world, becoming endemic in many of those countries and killing millions of wild and domestic rabbits. The two main strains to which most vets and bunny owners refer are RHDV and the more recent RHDV2, which first appeared in 2010.
The original RHDV strain has an incubation period of only 1-3 days, with death occurring 12-36 hours after the first onset of symptoms. However, most affected with RHDV are peracute, meaning they are usually found dead within a few hours of eating and behaving normally (Harcourt-Brown, 2018). The mortality rate is 70-90%. Although all domestic rabbit breeds are vulnerable, rabbits under the age of 2 months do not fall ill and if they are exposed to the virus, they develop an immunity.
RHDV2 is rapidly becoming the dominant strain worldwide and it is the strain that is now here in North America. It has the same clinical signs as RHDV, but baby bunnies do not have the same natural immunity to it. It has also spread to hares, cottontails, jackrabbits and other North American native species, while RHDV only affects the European rabbit (Oryctolagus cuniculi), from which our domestic rabbits descend. The incubation period for RHDV2 is 3-9 days and the mortality rate varies considerably from 5-70% (World Organization of Animal Health, 2016) depending on how the disease manifests itself. Infected rabbits more often manifest milder symptoms, which can help them survive it.
Both strains primarily attack the liver and spleen. Most consistent post-mortem lesions are hepatic necrosis and splenomegaly (Spickler, 2016). The evidence of hemorrhaging can also be seen in the heart, lungs and kidneys post-mortem. The cause of death is internal hemorrhaging or liver failure.
The disease manifests as the following:
The virus kills quickly, giving the owner little chance to save their bunny. If you live in an outbreak area, be watchful for the following signs:
If you come across a dead wild hare or rabbit, do not touch! Contact your local Fish and Wildlife office. Any sudden death of pet rabbits should be reported to your veterinarian ASAP.
The virus is spread easily and is extremely difficult to eradicate. It survives freezing temperatures and can endure 122F (50C) for up to one hour. Studies show that it can survive outside the host for 10-19 months at room temperature in a controlled setting (Harcourt-Brown, 2002). It can remain viable for several months in an outside environment. Rabbits may become infected the following ways:
At this time, it is unknown if recovered rabbits can transmit to other rabbits.
There are several vaccines available in Europe that will treat one and/or both strains of the virus. In the Fall of 2021 US company, Medgene Labs, received Emergency Use Authorization from the USDA for their two-dose regimen vaccine. The second dose is given 21 days after the initial injection, and the bunny is fully immunized 14 days afterward the second dose.
The disease is usually diagnosed post-mortem, but a vet may suspected it, especially if a household has recently experienced a sudden unexpected death of other rabbits. If a vet surmises a rabbit of being infected with the virus, the bunny must be isolated and appropriate supportive care given. Supportive care may include syringe feedings, applying heat, fluid therapy, pain control, etc. Anyone caring for the rabbit must be wearing appropriate personal protective equipment (gloves, gown, shoe covers, etc).
The best way to keep your rabbits safe, regardless of vaccination status, is to do the following:
There are a number of products that kill the rabbit hemorrhagic disease virus. If you have a cleaning product at home that kills feline calicivirus, then it should also be effective against RHDV (Harcourt-Brown, 2018). These are the most easily available products:
Read USDA guidelines on how to properly use bleach and Virkon for disinfection purposes.
How to Make Your Own Sanitizing Foot Bath
You can purchase disinfectant foot baths online, however, you can also make your own. Take a metal tray, such as a cookie sheet. The sides should be high enough to keep liquid inside (approximately 2 inches). Place an outdoor mat inside the tray. Be sure that the mat fits well within the tray. Soak the mat with a disinfectant solution (be sure to follow the label instructions). The mat should be submerged enough so the soles of the shoes stay wet for the required time. The soles of your shoes should be clean of dirt and debris BEFORE you disinfect them, as the dirt and debris interferes, preventing the virus from being killed. Wet the soles with the solution and keep them wet per disinfectant's label instructions. Afterwards, the shoes can air dry.
Abrantes J., et al. Rabbit haemorrhagic disease (RHD) and rabbit haemorrhagic disease virus: a review. Vet Res 43, 12 (2012) https://doi.org/10.1186/1297-9716-43-12
Capucci L., et al. Increased pathogenicity in rabbit haemorrhagic disease virus type 2. Veterinary Record 180, 426 (2017) http://dx.doi.org/10.1136.vr.104132
Harcourt-Brown, F. Rabbit haemorrhagic disease and its variants (Lagoviruses). August 2018
Hollwarth, A. Rabbit haemorrhagic disease 1 and 2: Diagnosis and treatment of the highly contagious viral disease. October 2019
House Rabbit Society. Rabbit Hemorrhagic Disease Virus (RHDV). May 2020
OIE. Rabbit Haemorrhagic Disease. January 2019
Science Direct. Rabbit Hemorrhagic Disease
Spickler, Anna Rovid. 2016. Rabbit Hemorrhagic Disease. Retrieved from http://www.cfsph.iastate.edu/DiseaseInfo/factsheets.php
USDA. Factsheet: Rabbit Hemorrhagic Disease. October 2019
USDA. General Guidance for Cleaning and Disinfection of Rabbit Hemorrhagic Disease Virus (RHDV) Contaminated Premises. April 2020
The information presented is for educational purposes only and does not substitute veterinarian care. This information should not be used for diagnostic purposes, for treatment of an illness or injury and never should be substituted for veterinarian care by a licensed veterinary practitioner. The Educated Rabbit cannot be held responsible for the accuracy of the information contained, nor be held responsible for any action, based on information found in The Educated Rabbit.
Seek advice from your veterinary professional for any rabbit health issues and before administering any drugs!