At present, the large-scale and intensive development of duck breeding and the frequent exchange of domestic poultry breeds have led to the continuous emergence of new duck diseases, the increase of the types of epidemic diseases, the increase of the spreading ways, and the easy formation of high incidence, among them the influence has the following big several kinds, should add the prevention.
Riemerella anatipestifer disease, Riemerella anatipestifer disease, also known as infectious serositis of ducklings. This disease was first reported in our country in 1982, and now it has become one of the most serious infectious diseases in ducks, mainly affecting ducklings of 2-7 weeks old. The infection rate is above 90% , the morbidity rate is above 60% , and the mortality rate is different. There were 3 types of clinical symptoms. Most acute type: sudden death without obvious symptoms. Acute type: narcolepsy, necking or mouth on the ground, weak legs, unwilling to walk or Shake, lying on the back, legs like swimming, loss of appetite or even waste, eyes and nose serous or mucous secretions, the eyes are often adherent or even detached; diarrhea is green or yellow-green; near-death neurologic symptoms, such as shaking head and tail, spasms, arches reverse tension. Chronic type: common 4-7 weeks old ducks, depression, head and neck tilt, easy to be startled group, turn around or backward, dysplasia, gradually wasting, the main pathological features are pericardium, cellulose exudates covered the serosa of the liver and air sacs. Diagnosis can be made by isolation and identification of bacteria. The Florfenicol, gentamicin, enrofloxacin and cephalosporins were effective against the disease. The results of domestic trials showed that oil-emulsion vaccine was the best and tissue-inactivated vaccine was the worst.
The hepatitis is RNA hepatitis virus. The course of the disease was short and most of them died 3-4 days after onset. At the beginning of the disease, the spirit of paralysis, do not want to walk, appetite waste away, half-closed eyes in a coma state, some diarrhea, feces thin with green. Soon, the sick duck is nervous symptoms, restlessness, dyskinesia, body tilt to one side, spasms, death. The postmortem postmortem postmortem postmortem arches. The main lesion in the liver, often manifested as hepatomegaly, soft texture, the appearance of light red or mottled, the surface of the bleeding spot or bleeding spots. The gallbladder is swollen and filled with bile. The mortality of the disease is very high, and the high immune serum can be used for early treatment or passive immunization. Prevention: the hatched ducklings can be passively immunized by intramuscular injection of vaccine or virus embryo fluid 2 weeks before laying eggs, and the ducklings can also be directly vaccinated with attenuated vaccine.
Mixed infection and complex disease, the disease usually by two or more than two kinds of pathogens at the same time or successively to the duck body invasion and harm, that is, mixed infection and secondary infection. The specific manifestation is the pathogenic characteristics of the respective pathogens, or the common cause of similar and related clinical symptoms and complex disease, resulting in mixed infection and complex disease of the direct cause is the change of the internal and external environment of the body. If feed additives and antibiotics are used frequently, the balance of normal flora in intestinal tract will be disturbed, especially the quantity and pathogenicity of E. coli and salmonella, thus causing endogenous invasion and disease. In the external environment, in addition to improper sanitary disinfection measures, incorrect use of various vaccines, multi-livestock and poultry co-breeding, etc. , once a disease or other stress factors, the body’s immunity decline, results mixed infection was inevitable.
Avian influenza virus type A is an infectious disease of poultry caused by influenza virus type A. after infection, the virus may present mild respiratory and digestive symptoms with low mortality, or performance for more serious systemic, hemorrhagic, septicemia symptoms, higher mortality. These symptoms are mainly caused by avian influenza. Ducks are a large reservoir of influenza viruses, and they are an important channel of transmission of avian influenza. The ducks were found to have anorexia after infection, and only drank water and had watery stools with white or yellow color. Some of the Ducks were found to have nervous symptoms before death, such as dehydration and emaciation, death occurred 2-3 days after onset.
Avian Pasteurella multocida disease, avian Pasteurella multocida disease, also known as avian cholera. Divided into the most acute, acute and chronic type. The most acute, acute type often occurs suddenly, without symptoms of death, autopsy shows the characteristics of septicaemic bleeding, but occasionally sporadic. Common for chronic type, mainly manifested as respiratory symptoms and arthritis, claudication, wing ptosis, clinical diagnosis because of no characteristic lesions sometimes misdiagnosed. In sporadic or endemic cases, the age of onset tends to be smaller. The effect of drug therapy is quick, but it is easy to relapse after withdrawal, easy to produce drug resistance, drug sensitivity test should be made to choose drugs, and constantly change drugs. Inactivated vaccine or attenuated vaccine can be used for preventive vaccination, the immune effect is better.