HBVC (Viral Hemorrhagic Disease of Rabbits) or necrotic hepatitis is an infectious disease with an acute course and high mortality rate, reaching 80-100%.
The first outbreak of viral hemorrhagic disease in rabbits was recorded in 1984, and the case of livestock in China caused the disease caused great damage. And the causative agent of the disease with rabbit imported from the country came to Europe. A dangerous rabbit disease in 1986 was also detected in the Russian Far East. And Italian farmers lost about 80 million rabbits, after which several hundred rabbit farms were closed. Outbreaks of disease and HBV in rabbits later, symptoms of HBV in rabbits were later recorded in other European countries, as well as in countries of Southeast Asia and the American continent.
Causes of the disease
The causative agent of HBVC is an RNA virus with extremely high survivability. The virus is capable of causing the disease, having been frozen for about five years or subjected to treatment with ether and chlorine. Susceptibility to the disease is observed in rabbits of all breeds, and with age, the animal is at greater risk of contracting hemorrhagic pneumonia. Young individuals remain untouched by a dangerous disease.
It was not possible to detect a relationship between the occurrence of HBV in rabbits and the time of year. The virus enters the body with food, water or the respiratory tract if a healthy animal is kept together with the diseased. In the latter case, infection can occur from bedding, general feeding, and mating. After slaughtering the livestock affected by HBVC, the causative agent of the disease remains in fur and skins for up to three months, so products from such raw materials can also partially become the source of the disease.
Symptoms of the disease
The incubation period of necrotic hepatitis is usually from several hours to 5 days. A feature of the disease is its sudden appearance, rapid development and the same onset of death, while the spread of the disease among the adult population is also lightning fast.
Sometimes the course of hemorrhagic disease is such that an apparently healthy rabbit can be dead in a couple of days.
Of the external manifestations of the disease, it is worth noting:
- depression in sick animals;
- lack of appetite or complete refusal of food;
- nervousness or lethargy;
- cramps in a rabbit, accompanied by a squeak, groans and throwing of the head;
- inflammation on the eyelids;
- discharge from the nose of yellow color with a possible admixture of blood.
On the second day after infection, the rabbit develops intravascular coagulation, hemorrhages appear in the internal organs. And pathological changes in the body are not limited to this. The liver suffers, lesions affect the spleen, heart, kidneys and gastrointestinal tract. Most animals die due to pulmonary edema.
The diagnosis of viral hemorrhagic disease of rabbits is made on the basis of the mass death of an adult population that did not receive a vaccine against HBV and its immunity to rabbit disease for up to 1.5–3 months. This takes into account the absence of vivid clinical signs, as well as laboratory data.
Methods of treating a disease
Unfortunately, it is impossible to destroy the causative agent of hemorrhagic disease and neutralize its effect on the body. Therefore, the treatment of HBV in the classical sense does not exist.
But with a single subcutaneous or intramuscular injection of 0.5 ml of special serum against rabbit viral hemorrhagic disease, the animal can provide a two-hour protective effect after injection. However, the effect can be obtained only with the introduction of funds in the very early stages of the disease.
The use of serum at the height of the disease is not only for the treatment of animals, but also to prevent the spread of hemorrhagic disease. With timely receipt of serum, you can save up to 90% of the livestock. Vaccination against the hemorrhagic hepatitis virus provides immunity three days after the procedure and with mass morbidity saves up to 60% of the herd.
In addition to the mandatory use of serum or vaccine, if HBV is detected in a dysfunctional economy, it is necessary:
- thorough medical examinations of animals to identify sick rabbits;
- comprehensive disinfection and cleaning of places for walking and cages for rabbits, as well as equipment, equipment and sites for slaughter;
- measures for bloodless slaughter and burning with subsequent disposal in the order established by the veterinary service of the carcasses of sick and suspicious animals.
If there is no serum or vaccine, then the spread of the disease can be prevented only by slaughtering all the rabbits on the farm.
The carcasses of sick animals and young animals up to two months of age after slaughter are disposed of together with skins. The meat of adult rabbits without signs of disease after heat treatment is not dangerous. But the internal organs remaining after cutting, blood, paws, heads and other products must be disposed of.
Since the causative agent of the disease is stored in rabbit skins even after slaughter, such raw materials are stored in isolation, previously packaged in disinfected tissue. Further implementation and processing of skins is possible only after agreement with the veterinary authorities.
Methods of prevention of HBV
HBV and livestock loss can only be avoided with regular vaccination and compliance with animal welfare rules.
There are several types of tissue inactivated vaccine effective against rabbit viral hemorrhagic disease. The first administration of the HBVC vaccine is carried out at the age of 45 days, then the rabbits are vaccinated after three months. Three days after the first receipt of the vaccine, rabbits have intense immunity. Further vaccination takes place for life with a frequency of six months.
Females awaiting offspring are vaccinated at any stage of pregnancy. At the same time, a litter born from a vaccinated rabbit receives full immunity from hemorrhagic disease for a period of 30 to 60 days.
To provide a preventive effect and give the animal immunity for thirty days, passive immunization of rabbit livestock with serum from HBV will help.