The characteristics and comprehensive prevention and control of current pig blue ear disease (PRRS)
Wumo Veterinary 20210722
Regarding the pathogenic
pc blue ear disease (PRRS) standardized name is pig reproductive and respiratory syndrome, and its pathogen is pig blue ear disease virus (PRRSV). The virus mainly infects domestic pigs and wild boars, and all pigs are susceptible and can spread horizontally or vertically. The lesions caused by bull's eye are relatively concentrated in the respiratory system and reproductive system, and can cause severe respiratory and reproductive system lesions. Positive pigs excrete viruses through saliva, nasal secretions, semen, feces, urine, and milk. Pollutants, insects, rats, birds and other intermediate transmission vectors can carry and spread the virus. In recent years, PRRSV has obvious evolutionary mutation characteristics, and the virulence of the strain has been continuously enhanced. The popular strains in my country are mainly lineages 1, 3, 5 and 8 (J Han et al, 2016), and various types of genotypes have evolved. The strains are complex and diverse, with fast mutations and frequent recombination. According to the test results of the National Laboratory, the main epidemic strains in China are HP-PRRSV and NADC30-like strains.
Symptoms
Symptoms symptoms have different symptoms depending on gender and age. General symptoms of female livestock include: ① Adult breeding sows. Pregnant mother animals are mainly premature birth and miscarriage, and the miscarriage rate of infected people in the late stage of pregnancy is close to 100%; the birth of weak or mummy fetus is born; the ears, nipples, vulva, and tail skin of some positive sows are cyanotic; empty sows do not have estrus, are not obvious in estrus, or are repeatedly matched with infertility; the delivery period (delivery period) is early or postponed and lactation dysfunction is often caused; anorexia syndrome occurs before and after delivery. ② Adult species of boar . It is mainly manifested as intermittent cough, wheezing, difficulty breathing, poor appetite, decreased semen quality (less semen, abscess), and decreased sexual function. The spread rate is extremely fast, the overall incidence rate is as high as more than 50%, and the mortality rate is relatively low (within 4%) in the absence of severe secondary or concurrent infections. ③ Sucking piglets. The main symptoms are inflammation of the conjunctiva cornea, abrupt eyeballs, cyanosis of the eyes, sneezing or wheezing, dyspnea, pathological abdominal breathing, motor disorders, ataxia, , diarrhea or constipation, and the death rate is more than 30%. ④ Weaning and conserving pigs. Difficulty in breathing, abdominal breathing; occasionally, the ears gradually turn purple, the skin on the surface of the body becomes purple, the movement is dysfunctional, the hair is rough and shiny, the body is thin, the skin on the surface of the body is pale and anemia, and the growth rate is significantly slowed down. The traditional antibiotic treatment plan often has little effect, and the death rate is as high as more than 20%. ⑤Commercial fattening pigs. Common high fever and high fever, stubborn cough and asthma, purple skin on the surface, poor conventional treatment effect and prone to recurrence and rebound.
anatomical changes are common in interstitial pneumonia . The interstitial lung is significantly widened due to inflammatory edema, bleeding points are spread in the subcutaneous tissue, conjunctival keratitis, the systemic lymph nodes swelling to varying degrees, and dark necrotic lesions can be seen on the section, and sometimes renal edema and scattered bleeding can also be seen. There are obvious hemorrhage spots on the surface of the fetus in the later stage of pregnancy. If the disease course is longer, the pathological changes will be more complicated due to secondary (or concurrent) swine fever, , parasitol, and erythrocyte disease.
Pig farm risk warning
In the severe situation of responding to major animal epidemics such as "non-plague", modern large-scale pig farms and small and medium-sized pig farms in rural and pastoral areas should establish and improve the risk warning and evaluation mechanism for major animal epidemics on their own farms, and actively carry out early prevention and control to ensure that they will not suffer major animal epidemic losses. Whether the pigs in the farm are infected with PRRSV will have some characteristic manifestations. The general judgment criteria are as follows: batch pregnant sows have miscarriage or premature birth in the short term. If the incidence rate of such a type exceeds 10%, it should be suspected that PRRSV is positive; the number of adapted sows has increased significantly, and the body temperature is generally abnormally increased at the beginning of the disease; the yield rate of stillbirth of sows in the same batch exceeds 20%; the mortality rate of newborn piglets in the same batch exceeds 0% within one week after birth; parasipids, thoracic, streptococci, pasteuris, erythrocytes, etc. are batch infections and onset; the death rate of sows in the same batch exceeds 40%, etc. If the above two or more symptoms occur, the pig farm should take decisive actions to take targeted emergency response measures.
Prevention and control measures
Priority for vaccination. At present, one of the most effective measures to prevent PRRS in the medical history area (field) is to receive related vaccines. For self-bred and self-raised pig farms, vaccination of breeding pigs (♀♂) and commercial piglets is of great significance, and pigs that produce normal immune responses can obtain effective passive immune antibody protection. According to the summary of large-scale pig breeding and veterinary clinical practice in recent years, it is believed that at present, domestic pig farms are the first to be vaccinated with live attenuated virus (Relan'an). This vaccine is highly safe and has the best protection. It is the first choice for domestic domestic domestic domestic domestic domestic vaccine recommended by top experts. In practice, the effects of PRRS inactivated vaccines and subunit vaccines are limited. If affected by other factors such as immunosuppression and improper immune operation, it is very easy to cause immunity failure, which means that the actual protective effect is not ideal. Therefore, pig farms should consider prioritizing the use of vaccines with accurate effects.
Ensure source control. keeps the introduction level well. When the pig farm introduces pigs (♀♂) to the outside world or purchases commercial piglets for breeding, it is necessary to purchase them from formally qualified breeding pig farms or commercial piglet breeding farms in non-epidemic areas. It is strictly forbidden to purchase pigs from epidemic areas, threat areas or medical history farms. Before entering the pig, be sure to do a good job in isolation and breeding observation and animal disease risk assessment, and resolutely avoid positive pigs entering the farm (house/pen) and raising them in groups. Keep a close watch. During the breeding process, daily dynamic epidemic monitoring and disposal should be carried out seriously. Once a certain suspected case or dead pig in the group is found, isolation treatment, related pollutants and harmless disposal of dead animals should be carried out in a timely manner to strictly prevent the epidemic from further horizontal transmission within the group. Keep the biosafety level well. "Preventing imported cases from outside and preventing spread from inside" is the core task of pig farms to prevent major animal epidemics (infectious diseases). The key measure is to do a good job in biosafety prevention and control related work. The key point is to strictly prohibit intermediate transmission media such as vehicles, utensils, personnel, and other animals that are not related to our factory from entering this site (house/column) at will to spread related epidemics, and implement the strictest ban and ban management. If you must enter, strictly implement various control work such as veterinary health, epidemic prevention and disinfection.
Strengthen environmental control. Modern large-scale pig farms have extremely high control requirements for small breeding environments, which is a key link that determines the success or failure of current breeding. For the outside of the pig farm, it is necessary to prevent unrelated personnel, other animals (including wild birds), vehicles, utensils and common objects from outside the farm from entering the farm at will. Even if the managers of the farm enter the farm, they must strictly sanitation, epidemic prevention and disinfection of clothing, self-use objects, etc.; if there is breeding manure, domestic waste, and dead animals around the pig farm, they must be removed in a timely manner and harmless disposal in parallel, and strictly prevent pathogens from invading this farm through multiple channels such as soil, air, water sources, etc., causing the disease of healthy pigs. Within the pig farm, core functional areas such as living areas, production areas, decontamination workshops and centralized manure disposal areas should be reasonably planned and laid out to facilitate the management of daily feeding and epidemic prevention and control. Strict closed management is implemented within the pig farm (houses, pens). While preventing the entry of exogenous intermediate transmission media, we must actively carry out routine work such as breeding pollution control, cleaning and disinfection of environmental and utensils, preventing cold and heat from pigs, controlling the pig houses with constant temperature and humidity, ventilation and lighting, and try to eliminate various pathogenic factors (adverse stressors) in the environment, and control the incidence of pig herd infection within the normal range.
Health prevention (treatment before disease). In recent years, practice has proved that modern pig farms have actively adopted drug health prevention procedures to deal with major animal diseases such as ASF and PRRS. For targeted prevention of PRRS, it is recommended to use " Astragalus polysaccharide (original powder/granules) + Flufenico (original powder) + doxycycline (original powder)" or "Fuzheng Jiedu Powder (including isatis root, astragalus, Epimedium , Spotted halter , Toads , etc.) + Flufenico (original powder) + timikaoxin (original powder)" or "smoothing" to take oral treatment. Follow the instructions for use of the drug, mixing (wet) or mixed drinks can be done. 1 dose/d, feeding for 5-7 days.If there are more serious respiratory pathological symptoms in the pig herd, it is recommended to use "Maxing Shi Gan Powder (or Maxing Shi Gan Powder) + Fluphenicol (original powder) + Timicococcin (original powder)". This prescription has a significant effect on relieving cough and relieving asthma.
