Viral rabbit hemorrhagic disease: description, causes, treatment and vaccines

2024 Author: Howard Calhoun | [email protected]. Last modified: 2023-12-17 10:16

Rabbit breeding is practiced by many homesteaders and villagers. This is in most cases profitable and not too complicated. However, it is possible to make a profit from a farm of such specialization only if the animals are properly cared for. First of all, when keeping rabbits, maximum attention should be paid to preventing the spread of various kinds of infections. Otherwise, you can quickly lose all the livestock.

One of the most formidable diseases of these animals is VGBK. Treatment of hemorrhagic disease of rabbits is not carried out. There are practically no methods to save animals in case of infection. The drop during spread in the FHD herd is usually 90-100%.

Pathogen

Causes VGBK a special RNA-containing calcivirus with extremely high virulence. Activity, and very high, even at a temperature of 40-50 degrees, it can maintain more than five years. Fortunately, only rabbits are susceptible to this calcivirus. Other agricultural and domesticanimals, as well as humans, cannot contract an infection such as rabbit hemorrhagic disease.

The susceptibility of animals to VGBK is very high. Rabbits of any sex, all ages and breeds can be affected by this disease. The incidence statistics are not particularly dependent on the time of year. However, rabbits most often get sick with VGBK in autumn or winter.

The most sensitive to viral hemorrhagic disease are animals older than 3 months, weighing from 3 kg. Why the body of young rabbits is able to resist disease better than adults is still a mystery to scientists. Very often, the disease also affects pregnant and lactating females for unknown reasons.

A bit of history

For the first time, viral hemorrhagic disease of rabbits was recorded in China, in the area of Jiang Zu. Many farmers in this province have lost entire livestock in just a day. In Europe, calcivirus first appeared in 1986. This time, Italian farmers suffered. The death of animals began immediately after rabbit meat was brought into the country from China. For two years (1986-1988) VGBK covered almost the entire territory of Italy. Up to 600 dysfunctional households were recorded in the country. Many rabbit breeders simply went bankrupt. At the same time, Italian veterinarians and scientists were powerless to change anything. They couldn't even identify the virus, calling HFHD the X disease.

In Russia, infection of rabbits with calicivirus was first recorded in the Jewish Autonomous Okrug. On the very border with China, in the state farm "Far East", almost the entire livestock of animals died. Unfortunately, since, as in Italy, the disease was not identified, no measures were taken to prevent its spread at that time. The remaining rabbits were slaughtered at the meat packing plant, and the skins were sent to the felt factory. As a result, after some time, the disease manifested itself already in the Moscow region. Cases of infection were also recorded in other parts of the country.

To date, VGBK is common in most regions of Europe, in Southwest Asia, on the American continent and in Africa. The work to systematize data on this disease is being carried out by the International Epizootic Bureau.

How infection can occur

Viral rabbit hemorrhagic disease poses a danger to business not only because of the lack of treatment methods and one hundred percent mortality, but also because of the lightning spread. This infection can be transmitted in many ways. Very often, for example, farm personnel become the culprit in infecting animals. The virus is easily carried on both shoes and clothes. In addition, sources of infection can be:

• bedding;
• manure;
• feed;
• water;
• particles of the skin of sick animals.

Calcivirus is also transmitted simply by airborne droplets. In the skins of sick animals, it can persist for up to threemonths.

Rabbit hemorrhagic disease: symptoms of infection

There are only two main forms of VGBK: fulminant and acute. In the first case, only a few hours pass from the moment of infection of the animal to its death. In the evening, the owners can feed still he althy animals, and in the morning find them dead. In this case, the disease does not manifest itself clinically. Animals just die.

The acute form of VHD develops as quickly as, for example, myxomatosis. Viral hemorrhagic disease of rabbits in this case can last for several days. The incubation period is 2-4 days. Then the rabbits begin to show signs of depression, lack of appetite, and nervous system disorders. In animals, cramps of the limbs, tilting of the head can be observed. In this case, the rabbits suffer, groan or squeak.

At the final stage of the disease, a yellowish-red liquid begins to flow from the nasal openings of the animals. From the moment the first signs of the disease appear to the death of animals in the acute form of VHD, no more than 1-2 days pass. Infected pregnant rabbits always miscarry.

Patological changes

Viral hemorrhagic disease of rabbits got its name due to the fact that when opening the carcasses of dead animals, veterinarians always find multiple hemorrhages in almost all internal organs. In this case, the liver and kidneys are most affected in rabbits. The blood of animals after death may not clot for a long time.

The internal organs are especially affected in adult animals. The liver of dead rabbits is enlarged and ruptures easily due to its flabby consistency. It has an unnatural color - yellow-brown, sometimes with a red tint. It is in the liver of an infected rabbit that an increased concentration of calcivirus is observed. It is mainly due to its reproduction that its function is impaired.

The spleen of rabbits that died from HHD is slightly enlarged, also has a flabby texture and an unnatural (this time dark purple) color. The kidneys of dead rabbits are filled with blood, and the gastrointestinal tract is catarrhal. There are multiple hemorrhages in the intestines.

What kills rabbits

Death of HBV-infected animals, in addition to liver failure, occurs as a result of pulmonary edema. It is the rapid defeat of these two organs that explains the lightning-fast course of the disease. The lungs of dead animals are filled with blood and intensely edematous. At the same time, they are colored unevenly, and multiple dot and stripe hemorrhages are observed under the pleura.

Preventive measures

Despite the fact that HCHD calcivirus is transmitted in many ways, it is still possible to prevent infection in animals. Of course, the observance of sanitary standards in the rabbitry should also become an obstacle to the development of the disease. Cages and aviaries should be cleaned on time. Far from all disinfectants kill calcivirus. Therefore, you should use only special tools designed specifically for processingrabbitries.

It is very important to pay maximum attention to the quality of the feed purchased for animals. Grain and mixed feed should only be purchased from well-established farms with a good reputation.

Viral rabbit haemorrhagic disease: vaccine (varieties)

Keeping cages clean and buying quality barley and oats can greatly reduce the risk of spreading the disease. However, only universal vaccination will help to completely protect rabbits from HBV.

Although VGBK is not treated, scientists have created a vaccine against it. Moreover, several variants of it can be used on farms:

• associated freeze-dried (rabbit hemorrhagic disease vaccine, myxomatosis);
• tissue inactivated aluminum hydroxide;
• three variants of lyophilized tissue (formol-, teotropin- and thermovaccines);
• inactivated, used against HBV and pasteurellez.

Microbiologists have developed not only the actual vaccine against viral haemorrhagic disease of rabbits, but also a special serum. This remedy is good because it shows its protective effect already two hours after intramuscular injection.

Treatment

There are no specific treatments for a disease such as viral haemorrhagic disease of rabbits. However, in some cases, even those animals that already have clinical signs of the disease (the first ones) can be saved by introducing the above describedserum. But, of course, there is no guaranteed result in this case.

Vaccination

Prophylactic injections from VGBK are supposed to be given to animals 1.5-3 months of age once. The vaccine against hemorrhagic disease of rabbits is injected into the buttocks. Stable immunity is weakened in animals 6-8 months after injection. Rabbits bred for meat are usually slaughtered earlier. Therefore, they do not need to be re-vaccinated. Manufacturers are supposed to do injections at intervals of six months. Pregnant rabbits are allowed to be vaccinated at any stage of embryonic development.