Rabbit Hemorrhagic Disease (RHD) is a highly infectious and often fatal viral disease that affects wild and domestic rabbits. It is caused by the rabbit hemorrhagic disease virus (RHDV) and has been recognized as a significant threat to rabbit populations worldwide. This article will discuss the cause, significance, species affected, distribution, transmission, clinical signs, diagnosis, treatment, and management of RHD.
Cause
RHD is caused by a highly contagious calicivirus called rabbit hemorrhagic disease virus (RHDV). RHDV has several genogroups, including RHDV2, which is more recent and considered more virulent than the original RHDV1 strain. The virus is resistant to environmental stressors and can survive in the environment for several months.
Significance
RHD has significant implications for rabbit populations worldwide. Outbreaks have led to a significant decline in wild rabbit populations and have impacted predator populations that rely on rabbits as a food source. Domestic rabbits are also vulnerable to RHD, and outbreaks have led to substantial economic losses in the rabbit farming industry.
Species Affected
RHD primarily affects European rabbits (Oryctolagus cuniculus), but can also infect hares, cottontail rabbits, and other lagomorphs. Domestic rabbits are also susceptible to the disease.
Distribution
RHD has been reported in various parts of the world, including Europe, Asia, Africa, Australia, and the Americas. The disease was first identified in China in 1984 and rapidly spread to Europe, where it caused significant mortality in wild and domestic rabbit populations. The disease was introduced to Australia in 1996, where it led to the decline of wild rabbit populations.
Transmission
RHDV is transmitted through direct contact with infected rabbits or their secretions, as well as through contaminated surfaces, water, and feed. Insects such as flies and fleas can also transmit the virus. The virus can persist in the environment for several months, which can lead to infection of rabbits that have no direct contact with infected individuals.
Clinical Signs
The symptoms of RHD can vary depending on the strain of the virus and the age and health status of the rabbit. In some cases, infected rabbits may not show any clinical signs before death, while in others the symptoms may be severe and sudden.
The incubation period of RHD can range from one to five days. After the incubation period, the virus rapidly multiplies and spreads throughout the rabbit’s body, causing damage to the liver and other organs. Clinical signs may include:
- Sudden death: Some rabbits may die suddenly without showing any signs of illness.
- Anorexia: Infected rabbits may refuse to eat or drink.
- Lethargy: The rabbit may appear weak, tired, and unwilling to move.
- Fever: The rabbit may have an elevated body temperature.
- Respiratory distress: The rabbit may have difficulty breathing, gasping for air, and making wheezing or gurgling sounds.
- Bleeding: Infected rabbits may have bloody discharge from the nose, mouth, or rectum.
In some cases, the symptoms may be mild and can be mistaken for other conditions such as digestive problems or respiratory infections. Therefore, it is important to seek veterinary attention if any of these symptoms are observed in a rabbit, especially if there is a history of RHD in the area.
It is worth noting that RHDV2 can also cause clinical signs in hares, which can be similar to those seen in rabbits.
Diagnosis
Diagnosis of RHD is based on clinical signs, postmortem findings, and laboratory testing. Postmortem examination of affected rabbits may reveal hemorrhages in various organs, and laboratory testing can confirm the presence of the virus.
Treatment
There is no specific treatment for RHD. Once clinical signs are observed, death usually occurs within 12-36 hours. Supportive care can be provided to affected rabbits to help alleviate clinical signs, but the prognosis is poor.
Management
There is no specific treatment for RHD, but supportive care can be provided to affected animals. In the case of pet rabbits, veterinary care can be sought to help manage their symptoms and make them more comfortable.
Prevention is the key to managing RHD outbreaks. It is important to limit contact between wild and domestic rabbits as much as possible to prevent transmission of the virus. This can be achieved by keeping domestic rabbits indoors or in secure enclosures, and avoiding contact with wild rabbits.
Biosecurity measures should be taken to limit the spread of the virus. These measures include disinfecting equipment, clothing, and footwear before and after contact with rabbits, and quarantining new rabbits before introducing them to an existing herd.
In areas where RHD is known to occur, vaccination can be an effective tool for preventing the disease in domestic rabbits. Several vaccines are available in different countries, and their use is subject to local regulations.
In the case of wild rabbit populations, management efforts focus on monitoring the spread of the disease and limiting its impact on the population. This can involve measures such as culling infected animals to prevent the spread of the virus, and tracking the spread of the disease through surveillance and testing programs.
Overall, effective management of RHD requires a coordinated effort between government agencies, wildlife organizations, and individual rabbit owners. By working together to prevent the spread of the virus, we can help protect both domestic and wild rabbit populations from the devastating effects of RHD.
Conclusion
Rabbit hemorrhagic disease is a significant threat to both wild and domesticated rabbits. The disease is highly contagious and can spread rapidly, making it difficult to control once an outbreak occurs. However, with proper management strategies, it is possible to reduce the spread of the virus and protect rabbit populations from significant losses.
By implementing biosecurity measures, monitoring rabbit populations, and euthanizing infected rabbits, we can prevent the spread of RHD and limit the impact of this devastating disease on rabbit populations.
Learn more about wildlife diseases, behaviors, and environmental issues via the sources and further reading or by browsing additional articles here.
Sources
- Mitrofanov, I., & Dukhovny, V. (2020). Rabbit hemorrhagic disease virus: biology, pathogenesis and host specificity. Veterinary Sciences, 7(2), 68. doi: 10.3390/vetsci7020068
- Rouco, C., Aguilar, I., & Santoro, S. (2021). Current state of rabbit hemorrhagic disease virus 2 (RHDV2) in wild rabbits in the Iberian Peninsula. Frontiers in Veterinary Science, 8, 661624. doi: 10.3389/fvets.2021.661624
- Veterinary Laboratories Agency. (2010). The diagnosis of rabbit hemorrhagic disease (RHD). Retrieved from https://www.gov.uk/government/publications/rabbit-haemorrhagic-disease-diagnosis
- World Organisation for Animal Health. (2021). Rabbit hemorrhagic disease. Retrieved from https://www.oie.int/en/animal-health-in-the-world/animal-diseases/rabbit-haemorrhagic-disease/
Further Reading
- Delibes-Mateos, M., Delgado, M. P., Ferreras, P., Villafuerte, R., & Smith, G. C. (2008). Long-term changes in game species over a long period of transformation in Spain: abundance of the wild rabbit, red-legged partridge and quail. Biodiversity and Conservation, 17(4), 869-881. doi: 10.1007/s10531-007-9302-1
- Dalton, K. P., Nicieza, I., Abrantes, J., Esteves, P. J., & Parra, F. (2014). Spread of new variant RHDV in domestic rabbits on the Iberian Peninsula. Veterinary Microbiology, 169(1-2), 67-73. doi: 10.1016/j.vetmic.2013.11.007
- Le Gall-Reculé, G., Zwingelstein, F., Laurent, S., de Boisseson, C., Portejoie, Y., Rasschaert, D., & Bergoin, M. (2013). Detection of a new variant of rabbit hemorrhagic disease virus in France. Veterinary Record, 173(6), 137. doi: 10.1136/vr.101303
- Lopes, A. M., Dalton, K. P., Magalhães, M. J., Parra, F., Esteves, P. J., & Holmes, E. C. (2015). Full genomic analysis of new variant rabbit hemorrhagic disease virus revealed multiple recombination events. Journal of General Virology, 96(5), 1309-1319. doi: 10.1099/vir.0.000060