Rabbit hemorrhagic disease (RHD) is a usually fatal disease affecting almost exclusively lagomorphs caused by the rabbit hemorrhagic disease viruses (RHDV). While initial outbreaks of RHDV-1 occurred in Europe and Asia, RHDV-2 has emerged and spread across the globe within the span of the last 10 years. RHDV-2 has resulted in major outbreaks of RHD in wild and domestic rabbits in Washington State and the North American Southwest (USA and Mexico) since 2020.
RHDV-2 causes a severe necrotizing hepatitis in lagomorphs that results in secondary disseminated intravascular coagulation and death. Death is often peracute and other signs may not be recognized prior to death. RHDV-2 is a calicivirus that is environmentally stable and transmitted primarily by fomites via the oral-fecal route. Due to the ease in inadvertent exposure via fomites and the seriousness of the disease, vaccination is recommended as the primary means to prevent infection. Initial importation of unapproved European killed vaccines was allowed for affected states only and were difficult and expensive to acquire.
Medgene Labs has recently received United States Department of Agriculture Center for Veterinary Biologics (USDA-CVB) emergency use approval for their inactivated recombinant subunit protein vaccine, increasing availability and ease of acquiring vaccines across the country. Due to vaccine developments, vaccination against RHDV-2 for domestic rabbits is now widely available and strongly encouraged.
About the presenter
Dr. Amanda Jones is a consultant for Medgene Labs, and a supervising veterinarian for the Medgene Labs Texas Field Safety Site. Dr. Jones is also the owner of Central Texas Rabbit Herd Management in Killeen, Texas and an associate veterinarian for Animal Emergency Services of Killeen. Dr. Jones is a 2014 Cum Laude graduate of the Texas A&M College of Veterinary Medicine and… [MORE]
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Dr. Jones generously answered virtually every question entered during the live event. A few remaining questions were answered by email correspondence between the speaker and the attendee, and are now posted below:
I have heard of some practices opening the vaccine, drawing it up into individually dosed syringes, and they will then use these syringes up to at least several days after they have been drawn into the syringes. Generally, with other vaccines, they are supposed to be discarded if they have been in the syringe over 24 hours, so I was curious if this is a safe way to try to use the vaccine over a longer period of time or if this is not recommended. If this is a possible solution to make the vaccine last longer, how long can they be kept in the syringes?
I would not recommend storing the vaccine in individual syringes over keeping it in the glass vial it comes in. We know that the vaccine is stable in the glass vial and that glass is unreactive. Plastic can occasionally bind proteins and no research has been done on the vaccine stability stored in a syringe. Without research to verify there is no impact on the vaccine, I would not recommend it as a general practice.
How do you handle a case where you have suspicion for this disease but unconfirmed and owner declines any treatment other than supportive and takes pet home to die later and was buried by owner.
Unfortunately, there isn’t much that can be done. If you are very suspicious, you could call the state vet for guidance and if they have additional resources to ensure proper testing.
At the USAHA meeting, Medgene gave a presentation that discussed some mortality cases (multiple but details were not provided on exact numbers) shortly after vaccination that was attributed to transport stress. Was curious how that information ties into the information provided today?
As I did not attend that presentation, I am not sure of exactly what was said. Medgene strived to have necropsies performed for any rabbit that died in temporal association with the vaccine. All necropsies I reviewed showed either an underlying condition that was responsible for death or were inconclusive due to advanced decomposition. There have been some cases where rabbits had episodes of GI stasis in close timing with vaccination that may have been associated with the stress of traveling, but those rabbits recovered with supportive care.
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