Etiology and Prevention and treatment of Duck hemorrhagic Disease

Duck hemorrhagic disease (DHD) is an infectious disease caused by a new herpesvirus (DHV type II) that can infect ducks of all breeds and ages. Because of the disease duck wings feather tube, upper beak end and claw tip foot web often bleeding purple black, commonly known as duck "black feather disease", duck "black tube disease" and duck "purple beak black foot disease"; according to the disease characteristic autopsy lesions also known as duck bleeding disease. At present, the disease has occurred in Fujian, Guangdong, Zhejiang and other southern provinces in China, and the infected ducks are easy to be complicated or secondary bacterial infectious diseases (such as duck infectious serositis, duck colibacillosis, etc.) or viral infectious diseases (such as duckling viral hepatitis, duck influenza, etc.), so they are easy to be ignored by people.

1. epidemic characteristics

Muscovy duck was the most susceptible to infection. The disease has not been found in other birds and mammals. The disease occurs mostly in ducks aged 10~55 days, but it also occurs in ducks of other ages. Morbidity and mortality were different and closely related to duck age. The incidence and mortality increased with age, sometimes as high as 80%. The occurrence of this disease has no obvious seasonality, but it occurs more frequently in cold weather or rainy weather.

2. clinical symptoms

The characteristic clinical symptoms of this disease are bleeding or congestion in the feather tubes of both wings of sick ducks or dead ducks. The appearance is purple-black, and the bleeding black feather tubes are easy to break and fall off. The upper beak end, claw tip and foot web end of dead ducks were cyanotic and purple-black. Yellow liquid flows out of the mouth and nose of dead ducks, staining the front end of the upper beak and feathers around the mouth, and some feathers are even dyed yellow.

3. autopsy lesion

The characteristic pathological changes of this disease were hemorrhage in feather duct and hemorrhage or congestion in tissues and organs. The specific manifestations are slightly enlarged liver, dendritic hemorrhage or congestion, and occasional white necrotic spots; pancreas often bleeding, bleeding spots or bleeding spots can be seen, or the whole pancreas is bleeding red. Small intestine, rectum, cecum obvious bleeding, sometimes bleeding ring can be seen in the small intestine. Spleen, kidney, brain, bursa of Fabricius and other mild bleeding or congestion.

4. diagnosis

According to the characteristic clinical symptoms and pathological changes of diseased ducks, it is not difficult to make a diagnosis. Diagnosis of the disease depends on laboratory methods. In clinical diagnosis, the disease is easy to be confused with duckling viral hepatitis, duck plague, duck influenza, duck coccidiosis, breeding duck necrotizing enteritis and other diseases, and should be distinguished according to the clinical symptoms and characteristic pathological changes of each disease. Necrotizing enteritis of breeding duck is a disease that occurs frequently in breeding duck in autumn and winter. Clinical diagnosis is characterized by weakness, lack of appetite, inability to stand and sudden death and intestinal mucosa necrosis. The disease can occur in ducks of different ages. In addition to intestinal bleeding, pancreas, liver and kidney all have different degrees of bleeding.

5. control methods

Different preventive measures can be taken according to different characteristics of its incidence. In meat duck, some duck farms, the occurrence of this disease concentrated in a certain age period (e.g. 20~35 days old), while other ages rarely or do not occur, for this case, only need to inject duck hemorrhagic disease high immunity yolk antibody (1~1.5 ml/feather) 2~3 days before susceptible age; and some duck farms have disease above a certain age (e.g. 20 days old), for this case, need to inject duck hemorrhagic disease attenuated vaccine (0.2~0.5 ml/feather) within 10 days old. For breeding ducks or laying ducks, in addition to the same immunization as ducklings at the brooding stage, it is necessary to re-inject inactivated duck hemorrhagic disease vaccine (0.5~1 ml/feather) subcutaneously in the back of the neck or leg groin 10~12 days before opening, so as to prevent the egg drop caused by the disease.

In addition to strengthening feeding management and disinfection, duck hemorrhagic disease yolk antibody (1.5~3 ml/feather) should be injected as soon as possible, and broad-spectrum antibiotics should be administered to prevent secondary bacterial infectious diseases.