Pig breeding and respiratory syndrome originated from the United States in the 1980s, while the Netherlands promoted viral isolation in the early 1990s. At present, pig breeding and respiratory syndrome diseases are still prevalent in various pig farming countries and have become a key factor affecting pig breeding disorders and respiratory diseases. Pig breeding and respiratory syndrome diseases are prone to cause serious economic losses to pig farmers in my country. In order to promote the development of my country's breeding industry and improve the economic benefits of farmers, farmers need to further understand pig breeding and respiratory syndrome diseases and take effective prevention and control measures to prevent them in order to ensure the health and safety of pigs. The following analysis is now carried out on the epidemiology, clinical symptoms, laboratory diagnosis and prevention and control measures of pig breeding and respiratory syndrome.
1 and Epidemiology of pig breeding and respiratory syndrome
pigs are the only animals infected with PRRSV virus and have adverse clinical manifestations. Pig breeding and respiratory syndrome has the characteristics of rapid transmission speed, mainly through respiratory infection channels or vertical transmission, invading breeding sows and piglets, and the incidence of fattening pigs is mild. Sick pigs and poisonous pigs are important sources of infection for pig breeding and respiratory syndrome diseases. Infected sows are detoxified, such as nasal secretions, feces, and urine.
The semen collection was carried out on the 3rd to 27th and 43rd after the boar was attacked by the virus, and the isolated virus can be obtained. Viruses can be detected in the blood of sick pigs from the 7th to the 14th. However, after the semen containing the virus is transmitted to the sow, the sows can easily become ill, and PRRSV antibodies can be detected in the onset sows after 21 days. After sows are conceived, in the middle and late stages of pregnancy, the sows and fetus are susceptible to PRRSV virus. This virus replicates in macrophages, which easily destroys its structure, leading to generalized vasculitis and other organs and tissues, resulting in extensive spleen necrosis and serious lymph node damage, which will cause severe impact on the immune system of infected pigs. Sick pigs will eventually die due to heart failure, lung tracheal failure, immune failure, etc.
2. Clinical symptoms of pig breeding and respiratory syndrome
Clinical symptoms of pig breeding and respiratory syndrome have the characteristics of a higher probability of stillbirth and a higher probability of death from lactation piglets, and the probability of death from lactation to fattening period is higher. At the same time, it was also found that the clinical symptoms of pig breeding and respiratory syndrome have strong immunosuppressive functions. It should be noted that there are obvious changes in the clinical symptoms between infected pigs and infected pigs, between the onset pigs and the onset pigs, and there are obvious differences in severity and duration. The clinical symptoms of pig breeding and respiratory syndrome are mainly divided into three types. The first type of adult pig is prone to loss of appetite, difficulty breathing, fever, and peripheral inflammation; the second type of piglet is prone to death before or after weaning, pneumonia, etc.; the third type of sow is prone to symptoms such as miscarriage, premature birth, stillbirth, and re-estrus.
According to relevant clinical data, the production capacity of diseased pigs continues to decline. The probability of suckling piglets is only 10.32%, up to 54.32%, and the probability of stillbirth is between 7.36% and 66.35%. The probability of incidence of weaned piglets and fattening pigs is only 1.23%-2.34%. The situation is not consistent in different regions around the world. The probability of miscarriage in late pregnancy can reach 3.85%-80.36%, and the probability of non-conviction and infertility can reach 10.24%, and the maximum can reach 50.31%. In addition, the probability of cyanotic virility in the ears, nipples, and vulva of sick pigs is 1.24%-5.24%. Based on German clinical data research, it has been confirmed that the significant feature of pig breeding and respiratory syndrome diseases is that miscarriage or premature birth occurs around 7 days before delivery, and the probability of death of piglets infected with the virus can reach more than 75.03%. Some sows are also prone to hind limb paralysis and the course of the disease will last about January to June. At this stage, the immunity and duration of sows after being infected with the virus are not very clear.
3. Laboratory diagnosis of pig breeding and respiratory syndrome
For sick pigs, after suffering from acute PRRVS virus, significant acute sepsis will occur clinically in the epiphany and mortal stages; systemic macrophages and vascular endothelial cells are too enlarged and activated; interstitial pneumonia and other pathological changes.The naked eye can see that the apical and heart lobes of the diseased piglets are dark red. A few cases have seen significant changes, showing only a large increase in the volume of the lungs, and a lot of fluid can seep out of the section; the brain and cerebellar leuconephrine blood vessels of most diseased pigs have dilated and congested blood vessels. The sick pigs have different degrees of congestion, bleeding, and swelling of lymph nodes throughout the body, and some of them are dark red.
4, Prevention and control measures for pig breeding and respiratory syndrome
Currently, there is no very effective drug treatment method for pig breeding and respiratory syndrome diseases, and the main use of comprehensive prevention and control methods and symptomatic treatment methods. The fundamental purpose is to eliminate viruses in sick pigs and poisonous pigs and effectively cut off the transmission path. To this end, farmers need to thoroughly remove infected weaned pigs to ensure that the virus is not available in the nursery room. In this way, as long as the same exhaust system as the contaminated pig houses are not used, pig breeding and respiratory syndrome infection will not occur. In addition, we must pay attention to quarantine and local testing of imported pigs to avoid the spread of pig breeding and respiratory syndrome diseases. Since pig breeding and respiratory syndrome diseases are mainly negative infections, continuous infection can occur at the individual and population levels, which also increases the difficulty of prevention and treatment. At present, the effective method to treat pig breeding and respiratory syndrome diseases is to use symptomatic treatment measures immediately once discovered, optimize the pig breeding environment and reduce the breeding density. It is also necessary to close the affected areas, restrict the flow of the affected pigs, and treat culling and burying the sick pigs in depth. Farmers can use hot water to rinse the infected pig house for more than three times, and then use formaldehyde disinfectants to disinfect to prevent the spread of the virus.
Summary: For pig breeding and respiratory syndrome diseases, farmers should pay great attention to it, and use effective prevention and control measures to strengthen the control effect, so as to avoid adverse effects on the pig herd and improve the economic benefits of farmers.
Author Profile: Zhao Yanjun Veterinarian
