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Beo

Rabbits and Diseases

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Everyone on here knows I do trekking, well on a trek I eat rabbit and some have asked how do I know if it has a disease, well
most rabbit diseases are rare, but there are a few one may worry about on occasion, the one to look for is RHD or Rabbit Hemorrhagic Disease, this can make a person anywhere from sick to being fatal, here is what I have learned on the disease, and some pics of what to look for. NOTE these pice may be ugly, nasty looking, graphic or disturbing to some. But this is well intended and a must for anyone that is going to skin a rabbit to eat.
Rabbit hemorrhagic disease is an extremely contagious and often fatal viral disease of domesticated and wild rabbits. This disease affects only rabbits of the species Oryctolagus cuniculus. Severe losses are common in unvaccinated animals; on some farms, most or all of the rabbits may die. This disease has also caused dramatic declines in some wild rabbit populations, particularly when it is first introduced. Rabbit hemorrhagic disease spreads very readily. The causative virus is very resistant to inactivation if it is protected by organic material; it may persist in chilled or frozen rabbit meat, as well as in decomposing carcasses in the environment, for months.
Rabbit hemorrhagic disease was first seen in the 1980s, but its origins are not completely understood. It may have emerged from avirulent caliciviruses circulating asymptomatically in European rabbit populations. The first known outbreak occurred in China in 1984, spread by angora rabbits that had been imported from Europe. Within nine months, this disease had killed 14 million domesticated rabbits in China. By the late 1990s, outbreaks had been reported from forty countries, and rabbit hemorrhagic disease had become endemic in wild rabbit populations in Europe, Australia and New Zealand. Other parts of the world including the Americas have experienced periodic outbreaks in domesticated rabbits. However, the species of wild rabbits found in North America are not susceptible to rabbit hemorrhagic disease, and this disease has been eradicated from domesticated rabbits each time.

Etiology
Rabbit hemorrhagic disease is caused by the rabbit hemorrhagic disease virus (RHDV), a member of the genus Lagovirus and family Caliciviridae. Many strains of RHDV appear to circulate in rabbit populations; these viruses can have distinct epidemiological and genetic characteristics. Only a single serotype is known, but two major subtypes exist: RHDV and the antigenic variant RHDVa. Nonpathogenic strains of RHDV have been identified in wild rabbits. One recent study suggests that different lineages of RHDV may have repeatedly emerged as epidemic viruses.

Species Affected
Rabbit hemorrhagic disease affects wild and domesticated members of the species Oryctolagus cuniculus. Other rabbit species including cottontails (Sylvilagus floridanus), black-tailed jackrabbits (Lepus californicus) and volcano rabbits (Romerolagus diazzi) do not seem to be susceptible. Similarly, European brown hares (Lepus europaeus) and varying (snowshoe) hares (Lepus americanus) are not affected by RHDV, although they are susceptible to a rabbit disease caused by a different calicivirus (European brown hare syndrome). Virus replication has not been reported in other mammals, including rabbit predators, although seroconversion can occur.

Geographic Distribution
Rabbit hemorrhagic disease is endemic in Australia, New Zealand, Cuba, parts of Asia and Africa, and most of Europe. Outbreaks have also been reported from domesticated rabbits in the Middle East and the Americas. Rabbit hemorrhagic disease was endemic in domesticated rabbits in Mexico from the late 1980s to 1991, and limited, independent outbreaks were reported from the U.S. in 2000 (Iowa), 2001 (Utah, Illinois, New York) and 2005 (Indiana). However, the disease was eradicated in each case, and rabbit hemorrhagic disease is not currently endemic in North America.

Transmission
Rabbit hemorrhagic disease is transmitted by direct contact with infected animals, as well as on fomites. Rabbits can acquire this disease through the oral, nasal or conjunctival routes. Most or all excretions including urine, feces and respiratory secretions are thought to contain virus. Animals may remain infectious for up to a month. RHDV can also be acquired by exposure to an infected carcass or hair from an infected animal. Long-term, persistent or latent infections have recently been recognized in rabbits. Whether viral RNA becomes reactivated in these carriers, and under what conditions, is unknown.
RHDV is readily spread on fomites including contaminated food, bedding and water. Flies and other insects are very efficient mechanical vectors; only a few virions are needed to infect a rabbit by the conjunctival route. Wild animals can transmit the virus mechanically. Although virus replication does not seem to occur in predators or scavengers, these animals can excrete RHDV in feces after eating infected rabbits.
RHDV is very resistant to inactivation when it is protected within tissues. This virus can survive for 7.5 months in tissue suspensions stored at 4C (39F), and for more than three months at 20C (68F) in dried organ homogenates. In one study, RHDV remained viable in decomposing rabbit carcasses at 22C (72F) for up to 20 days, but only seroconversion was reported at 26 or 30 days. However, virus-inoculated bovine liver left to decompose in New Zealand fields (to simulate infected carcasses) remained infectious for at least three months. Unprotected viruses shed in excretions are not thought to remain viable for more than a few weeks, and may lose some of their infectivity within one to two weeks. RHDV is also reported to survive exposure to pH 3.0, heat of 50C (122F) for an hour, and freeze-thaw cycles.

Incubation Period
The incubation period is one to three days.
All rabbits can become infected with RHDV, but young animals are resistant to disease. Typically, symptoms occur only in animals that are more than eight weeks old. Peracute or acute disease is described most often in domesticated rabbits, but subacute and chronic disease can also be seen. In peracute infections, infected rabbits develop a fever and die suddenly within 12 to 36 hours of its onset. The only symptoms may be terminal squeals followed rapidly by collapse and death. In acute disease, dullness, anorexia, congestion of the palpebral conjunctiva, or prostration may be seen. Animals with acute disease can also develop neurologic signs including incoordination, excitement, opisthotonos and paddling. Some rabbits turn and flip quickly in their cages; this can resemble convulsions or mania. Respiratory symptoms, including dyspnea, cyanosis and a terminal, bloodstained, frothy nasal discharge, sometimes occur. Lacrimation, ocular hemorrhages or epistaxis may also be seen. Some animals that recover from acute disease develop severe jaundice, with weight loss and lethargy, and die in a few weeks. In these animals, there may be diarrhea or constipation and abdominal dilatation just before death. Similar but milder symptoms are seen in the subacute form, and most of the rabbits may survive. Chronic, persistent infections are thought to be asymptomatic.

Rabbit. Severe epistaxis or bleeding

Rabbit, lungs. The trachea is filled with foam, and the lungs are mottled and noncollapsed (severe pulmonary edema).

Rabbit, heart. There are multiple epicardial hemorrhages.

Rabbit, liver. There is a large area of pallor (necrosis) with a prominent reticular pattern.

I eat a lot of rabbit when trekking so when skinning any rabbit to eat I always look for these signs, its a great tell if the rabbit has RHD. Boiling, cooking, and cutting it out WILL NOT WORK. If you see any of these signs DO NOT EAT THE RABBIT.
Hope this helps.
Beo,

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Updated 08-18-2008 at 09:22 AM by Beo

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Comments

  1. PipeBundle's Avatar
    Information like this is invaluable and I thank you for that.

    But the problem I see when information such as this is presented is....how would an inexperienced person know the difference between this and a normal healthy condition?

    What I would like to see done more often is direct comparison of abnormal conditions to the healthy state.
  2. your_comforting_company's Avatar
    If you've ever eaten a healthy rabbit, you know that these things do not look normal at all.

    Excellent info Beo. You taught me something that could save my life.

    Thanks Very Much for posting this.