Treatment and prevention of myxomatosis in rabbits

Treatment and prevention of myxomatosis in rabbits

Автор: Postolatiy V.V.. - Candidate of Veterinary Sciences

Myxomatosis - acute viral disease of mammals of the order Lagomorphs, characterized by serous-purulent conjunctivitis and the formation of tumors in the head area, anus and external genitalia. The disease causes a very large economic damage to rabbit breeders.  

The causative agent of the disease is the DNA virus Myxomatosis cuniculorum, leporipoxvirus, smallpox family- poxiviruses-  (Poxviridae); pathogenicity for humans and other animal species has not been established.

Historical reference

The disease was first described by Giuseppe Sanarelli and Alfonso Splendore in Uruguay and Brazil. (works 1896-1909); it was found, that the carrier of the virus was one of the local species of lagomorphs, developed immunity to it. In the 1950s. myxomatosis was deliberately introduced to control wild rabbits first in Australia, and then to France; in France the process got out of control, and the myxomatosis virus spread throughout Europe, because of what in 1952-1955. devastating epizootics were recorded. However, in the future, the strain of the pathogen became weakly pathogenic and the lethality from the virus decreased.. In 1954. panzootic myxomatosis emerged in Europe, when the disease spread at a speed of 450 km per year, covering all European countries. Since its discovery, the virus has mutated and has many varieties., - if there is a California strain in America, then in Europe strains of Neuromaxam and Nottingham are widespread.

Epizootological data

Wild hares are susceptible to the causative agent of the disease, pikas, as well as wild and domestic rabbits. Wild rabbits and hares are the natural reservoir of myxomatosis.. In fur farms, sick and recovered rabbits are usually the source of infection.. Sick animals shed the virus with a discharge from the nose and eyes.. The virus in the body of a sick rabbit is localized in the blood, skin, subcutaneous tissue and parenchymal organs. Mosquitoes are central to the spread of infection, flies, bugs and rabbit fleas, are mechanical carriers of the virus. Epizootics occur seasonally - this is usually associated with a period of mass reproduction of insect vectors (spring-summer period).) The virus in the body of blood-sucking insects can persist for up to six months.

Infection can also occur through airborne droplets during close contact of a healthy animal with a sick animal.. The surviving recovered rabbits have been carriers of myxomatosis for a long time.. Also noted, that after the death of a population of wild rabbits in a certain area, most of the microorganisms also die out, since they cannot develop in the body of animals of other species, and later, in the course of natural selection, a new generation of viruses appears, less effective pathogenic action, than the previous, but at the same time capable of surviving longer in rabbit populations, without having any effect on their numbers.

Clinical picture

Incubation (hidden) the period of illness is 6-18 days, depending on the general resistance of the animal's body. The disease is manifested by acute serous-purulent conjunctivitis. (swelling and sticking of the eyelids, mucopurulent discharge), head formation, anus and external genital organs of solid subcutaneous tumors. The scalp gathers in roll-like folds, ears droop ("Lion's head").

There are two forms of myxomatosis: classic (edematous) and nodular (nodular). The disease in the edematous form continues from 4 до 10 days, sometimes before 4 weeks. 100 % rabbits, patients with this form of myxomatosis, perish. The nodular form lasts 30-40 days, nodules (the size of a millet grain to a pigeon's egg) formed on the back, nose, paws, eyelids and other parts of the body, на 10-14 day they undergo necrosis. The mortality rate for this form is 50-70%. When treated with modern antiviral drugs and treatment of nodules with iodine, mortality is 30%.

The first signs of myxomatosis in both forms are: redness in the form of spots or the appearance of nodules on the skin in the eyelid area, on the ears and in other places. Before the first rash appears on the skin, 1-2 the day in rabbits the temperature rises to 40-41 ° C, and then comes back to normal. Duration of illness in adult rabbits 10-14 days, in young animals - to 7 days.

Recently, a new form of myxomatosis has begun to be registered in industrial-type farms., proceeding with the defeat of the respiratory system, lacrimation and runny nose. Autopsy of dead rabbits reveals gelatinous infiltrates in the subcutaneous tissue., and with a long course - pneumonia, multiple nodules ranging in size from a grain of millet to a pigeon's egg. Evolution of myxoma virus in rabbits with a predominance of atypical forms of the disease, such as nodular, respiratory, abortive; atypical and erased.

Pathological changes

With a nodular form of the course of the disease on the ears, small abscesses appear in the eyes and nose, which gradually increase and open up, secreting serous fluid and pus. With the edematous form of the course of the disease, edema of the subcutaneous tissue occurs at the sites of tumor formation. Whitish tumors, when cut, serous fluid is released from them. The lungs are swollen and contain inflammatory lesions. Hyperemia and enlargement of lymph nodes and spleen, enlargement of the renal parenchyma.

Diagnosis

Diagnosis is based on epizootic data, characteristic clinical signs, pathological changes and laboratory results. In a rabbit farm for laboratory analysis, a veterinarian-sanitary doctor selects pathological material (affected skin areas, blood samples, pieces of parenchymal organs). Pieces of skin and parenchymal organs are placed in a 10-15% formalin solution. The selected pathological material is placed in a thermos with ice and is sent on purpose to the regional veterinary laboratory for histological studies on myxomatosis. If the results of this study are negative and in the absence of characteristic clinical signs, the laboratory puts a biological sample (infected healthy rabbits in the laboratory die on days 3-6 with signs of myxomatosis). In the presence of a specific diagnosticum, PCR diagnostics are performed.

Immunity

Rabbits and hares that survived myxomatosis acquire almost lifelong immunity to this disease..

Differential diagnosis

Differentiate from infectious fibromatosis and staphylococcosis.

Treatment and prevention

In the treatment, the drug Ribavex is used – the combination of the components that make up the drug provides a wide range of antibacterial action, including against microorganisms, resistant to conventional remedies, as well as antiviral effect. The combination of active ingredients is highly active against a number of microorganisms: Staphylococcus spp., Streptococcus spp., Escherichia coli, Salmonella spp., Pasteurella spp., Clostridium spp., Haemophilus spp., Campylobacter spp., Klebsiella spp., Listeria monocytogenes, Mycoplasma spp., Chlamydia spp., Rickettsia spp., Borrelia spp., as well as in relation to DNA and RNA viruses. The solution for injection contains: enrofloxacin, trimethoprim and ribavirin. The latter is a guanisine analogue, used to stop the synthesis of viral RNA and thus, it is a nucleoside inhibitor and disrupts RNA metabolism, necessary for virus replication, showing a powerful antiviral effect. The drug is administered subcutaneously once a day for 3-5 days in the following doses: – rabbits - 1 ml 10 kg body weight; Antiviral drugs have proven themselves well: Fosprenil, Cycloferon and Imunofan, which are administered to especially valuable animals according to the instructions.

To prevent the disease and actively immunize rabbits against myxomatosis, various vaccines from different strains are used., made in the Czech Republic, Of Russia, Of Ukraine. The vaccine is administered intramuscularly, subcutaneously, for the immunization of healthy rabbits in safe, threatened and disadvantaged by myxomatosis and VGBK (rabbit viral hemorrhagic disease) points. In safe and threatened locations, rabbits are immunized once, starting at 1.5 months of age. Rabbits are vaccinated at any time during pregnancy.. In disadvantaged areas for myxomatosis and VGBK, clinically healthy rabbits and young rabbits from 45 days of age are vaccinated. Young growth through 3 months - revaccinated.

Each rabbit is vaccinated with a separate needle. During 20 days vaccinated rabbits are monitored. biological properties. The vaccine is harmless to rabbits when administered intramuscularly., subcutaneous injection and ensures the formation of intense immunity from the 3rd day after vaccination and lasts at least 12 months. Vaccine storage conditions must be strictly observed (store in a dry and dark place at a temperature of plus 2-8 °C). Owners don't always follow these rules, getting a lot of negative results. Sick rabbits should not be vaccinated..

Control measures

The causative agent of the disease is a DNA-containing virus. Virus sensitive to peroxidam, formalin and alkalis. Heating at 55 °C for 25 minutes inactivates the virus. At a temperature of 8-10 ° C, the virus persists 3 of the month, in the corpse of a rabbit - 7 days, in dried skins at a temperature of 15-20 ° C - for 10 months. Rabbits are vaccinated in the endangered area. When diagnosing rabbit myxomatosis, the farm and the settlement is declared unfavorable for myxomatosis of rabbits, quarantine is established with the definition of the boundary of the threatened zone and the necessary measures are taken to prevent and eliminate the disease: slaughter all rabbits, corpses are burned with skins. The meat of diseased animals should not be used for food.. In a dysfunctional animal farm, who have not yet developed clinical signs of the disease, can be slaughtered for meat. For household, where a case of rabbit myxomatosis was recorded, impose quarantine and carry out the following activities: disinfection barriers are installed on the roads and entrances to the farm, disinfection mats, which are refilled with 1% Viroflex solution. Contacts with domestic and wild animals are suppressed; to kill bed bugs, mosquitoes and other insects are disinfected daily in the premises with a safe drug ADDCON XNC, spray for rabbits; personnel are allowed to work on servicing rabbits only after changing personal shoes and clothes for overalls and safety shoes; any ties with other rabbit farms are terminated, vehicles are used within the village, it is not allowed to take things outside the unfavorable point, inventory, оборудования, fodder, products and other items; overalls and safety shoes are subject to daily disinfection with disinfectants.