Symptoms and Prevention and Treatment Methods of Porcine Pseudorabies

This disease is an acute infectious disease caused by pseudorabies virus that affects pigs and other animals alike. The disease is characterized by fever, intense itching (except in pigs), and symptoms of encephalomyelitis. Adult pigs often have latent infection, showing abortion, stillbirth and respiratory symptoms, while suckling piglets generally show neurological symptoms.

Pathogen:

The pathogen is Herpesviridae, Herpesvirus type I. The virus has strong resistance, but is very sensitive to heat, formaldehyde, ether and ultraviolet light. This virus has only one serotype.

Epidemiology:

This disease can occur in all four seasons, but is more common in winter and spring and during peak farrowing season. It often first occurs in sow houses during the peak of farrowing, with almost every litter affected, and the incidence rate reaches 100%. However, there is a peak in morbidity and mortality, after which it gradually decreases. Diseased pigs, virus-carrying pigs and virus-carrying rodents are important sources of infection for this disease. The virus is shed in nasal secretions, saliva, milk and urine, and susceptible pigs are mainly infected through direct contact and indirect contact. This disease can be transmitted through the digestive tract, respiratory tract, skin, mucous membranes and reproductive tract, and vertical transmission can also occur. Infected lactating sows can transmit the disease to suckling piglets through milk.

Clinical symptoms:

The incubation period of this disease is generally 3-6 days. Affected piglets show neurological symptoms, are restless and excited, have muscle spasms on the body surface, eyeball tremors, upward rolling of the eyes, and movement disorders. There are intermittent convulsions, and in severe cases opisthotonus occurs, with fever and high fever, and finally coma and death. The course of disease is 36-48 hours. Piglets that survive are often poorly developed and become stunted pigs. Sows mostly show transient and subclinical signs, and pregnant pigs develop abortion and stillbirth. The abortion rate is 50%.

Pathological changes:

The changes of diagnostic value are catarrhal or purulent hemorrhagic inflammation of the nasal cavity, edema of the tonsils accompanied by pharyngitis and laryngeal edema, serous infiltration of the arytenoid cartilage and epiglottic folds, often covered with fibrinous necrotic pseudomembrane, pulmonary edema, large amounts of frothy edematous fluid in the upper respiratory tract, and punctate or patchy hemorrhage visible on the laryngeal mucosa and serosa. Lymph nodes, especially mesenteric lymph nodes and mandibular lymph nodes, are congested, enlarged and occasionally hemorrhagic. There is patchy hemorrhage on the endocardium, punctate hemorrhagic inflammatory changes in the kidneys, large-area hemorrhage visible at the fundus of the stomach, hemorrhage and edema of the small intestinal mucosa with fold formation of the mucosa, patchy hemorrhage in the large intestine, congestion and edema of the meninges, punctate hemorrhage in the brain parenchyma, and in cases with a longer course, marked increases in pericardial fluid, thoracic and abdominal cavity fluid and cerebrospinal fluid, with large amounts of fibrinous exudate on the liver surface.

Diagnosis:

A preliminary diagnosis can be made based on clinical symptoms and epidemiology, but confirmation of this disease requires pathological diagnosis or laboratory diagnosis.

Vaccines can be used to prevent this disease. To thoroughly eradicate this disease, repeated quarantine is required and positive pigs must be culled. In addition, disinfection and rodent control should be done well to prevent the spread of the disease.