How to prevent and treat swine respiratory diseases? Lecture 3 detailed explanation

4. Swine influenza

Swine influenza (SI) is an extremely contagious respiratory infectious disease of pigs, characterized by sudden onset, sudden fever and other cold-like symptoms, with recovery being just as rapid as the onset. SI is caused by an influenza virus, of the same genus as the influenza viruses that infect humans, and this virus has the property of being able to infect both humans and animals. The appearance of SI in a herd is usually related to the introduction of new pigs into the farm.

(1) Symptoms:

Typical SI presents as a sudden severe outbreak affecting the entire herd. Within one or two days, almost all affected pigs begin to cough, sneeze, have difficulty breathing, discharge from the eyes and nose, and fever. At this stage the entire herd may refuse to eat. Affected animals lie down most of the time or refuse to move. The affected animals are severely ill, yet the symptoms disappear just as quickly. Almost all pigs can stand and feed by the seventh day. The mortality rate is very low; death occurs only when there is concurrent bacterial infection. When SI occurs, farm workers may also develop cold-like symptoms.

(2) Diagnosis:

If the typical SI symptoms described above appear, the herd should be suspected of being infected with this disease. At the same time, farm workers may also develop cold-like symptoms, but this is not absolute. Confirmation of SI requires serological methods.

There is no specific therapeutic drug for treating SI. Supportive therapy is recommended to relieve the suffering of the sick pigs. Antibiotics are used to control bacterial infection, and antipyretics may be helpful. Providing clean drinking water at all times during the outbreak is essential. Farm workers need to guard against infection by this disease. Likewise, pigs can also become infected with influenza from humans.

5. Swine pasteurellosis

Swine pasteurellosis, also known as swine hemorrhagic septicemia or pasteurellosis, is caused by Pasteurella multocida. This disease is sporadic, occasionally enzootic, and often occurs in hot, humid and rainy seasons. The carrier state in healthy pigs is common, and its occurrence is closely related to environmental conditions and feeding management. When the environment is poor and feeding is inadequate, the resistance of pigs declines, which can induce autoinfection and cause disease.

(1) Symptoms:

The most acute and acute forms manifest as septicemia and pleuropneumonia. Affected pigs show redness and swelling of the neck, difficulty breathing, cyanosis of the mucous membranes and skin, body temperature of 41-42 degrees, and a course of 1-2 days. The chronic form shows persistent coughing, difficulty breathing, purulent nasal discharge, emaciation and exhaustion.

(2) Pathological changes:

Acute swine pasteurellosis manifests as unilateral or bilateral fibrinous pneumonia. The lungs are enlarged, firm, with dark red or grayish-yellow liver-like lesions. The lung surface, pleura and epicardium are covered with fibrin. At the same time, there are petechial hemorrhages on the systemic mucous and serous membranes, and the head and neck lymph nodes are congested, hemorrhagic, red and swollen. In the chronic form, the center of the pneumonic foci undergoes necrosis, suppuration and fibrosis, with fibrinous adhesions of the pleura and pericardium.

(3) Control:

This disease can be treated with Bailiduo or Shahuang tablets, with good results. The use of inactivated vaccine or attenuated vaccine for immunization, together with improving the environment and feeding conditions, can prevent the disease.