How to prevent and treat swine respiratory diseases in winter?

Winter is a season with a high incidence of swine respiratory diseases. Swine respiratory diseases have caused serious losses to many pig farms, resulting in slow pig herd growth, reduced feed conversion efficiency, increased mortality, delayed marketing, and a vicious cycle in management, among other serious economic losses.

I. Occurrence characteristics

1. Mixed infection with multiple pathogens. Swine respiratory diseases are mostly caused by the interaction of multiple factors such as viruses, bacteria, parasites, environmental stress, and low immunity of the pigs themselves. Clinically, disease caused by a single factor is relatively rare, thereby manifesting in the pig respiratory system as a series of syndrome complexes, the so-called porcine respiratory disease complex (PRDC). It is often a dual or multiple infection between virus and virus, virus and bacteria, or bacteria and bacteria. Examples include porcine reproductive and respiratory syndrome and post-weaning multisystemic wasting syndrome.

2. A very large proportion of swine respiratory diseases change from acute to chronic, are difficult to eradicate in the pig herd, and become commonly occurring and frequently occurring diseases, with increasingly serious harm.

3. The disease condition becomes complicated and severe, mortality rises, and onset is acute with rapid spread.

4. Stress is an important predisposing factor. Such as climate change, excessive stocking density in the pig herd, weaning, mixing groups, moving groups, long-distance transport of pigs, excessive temperature variation and excessive humidity in the pig house, poor ventilation and poor air quality in the pig house (excessively high ammonia, hydrogen sulfide, and carbon dioxide), etc.

II. Prevention and control countermeasures

1. Comprehensive prevention and control measures. (1) Persist in self-breeding and self-raising. Establish a stable breeding pig herd and do not introduce breeding stock easily. If introduction is necessary, first clarify the epidemic situation of the source farm. In addition, serological testing should be carried out, and only negative pigs may be introduced. The introduction of positive virus-carrying pigs is strictly prohibited. After introduction, an appropriate isolation area must be established and monitoring must be done well. Generally, isolation and quarantine are required for 4 to 5 weeks, and only healthy animals may be mixed into the herd for rearing. (2) Achieve all-in/all-out. At least all-in/all-out should be achieved in the two stages of farrowing house and nursery. (3) Establish and improve the biosecurity system of the pig farm. Regularly disinfect the pig houses and environment, and maintain the cleanliness and hygiene of the pig houses, feeding and management tools, and the environment. On the one hand, this can prevent the introduction of external epidemic diseases. On the other hand, through strict sanitary and disinfection measures, the contamination of pathogenic microorganisms in the pig farm can be reduced to a minimum, which can control and reduce to the greatest extent the incidence rate and opportunities for secondary infection in infected pig herds. (4) Do a good job in pig herd feeding and management. Feeding and management of pigs at all stages should be done well to ensure the nutritional level of the pig herd and prohibit feeding moldy and spoiled feed, so as to improve pig herd immunity and thereby reduce the incidence of secondary infection and the losses caused by it. (5) Do a good job in immunization against major epidemic diseases. Such as immunization against classical swine fever, porcine pseudorabies, and mycoplasmal pneumonia of swine. (6) Adopt closed management within the pig farm. Visitors are prohibited from visiting the pig farm, reducing the flow of people and materials. Feeding personnel should minimize movement as much as possible. Reduce the number of entries and exits to the farm, and prohibit moving between pens and buildings and borrowing production tools.

2. Preventive and therapeutic measures. (1) Control the main primary diseases. Mycoplasmal pneumonia of swine, porcine reproductive and respiratory syndrome (blue ear disease), porcine type II circovirus disease, swine influenza, etc. are considered the chief culprits (primary diseases) of swine respiratory diseases. Therefore, when preventing respiratory diseases, the primary diseases must first be effectively controlled before other respiratory diseases can be correspondingly reduced. These diseases are all related to immunosuppression. To improve pig immunity, use astragalus polysaccharide injection combined with vitamin B1 + B12 + C by intramuscular injection, or use astragalus polysaccharide and multivitamins in drinking water. Of course, antiviral preparations such as interferon and leukocyte mediator can also be appropriately selected for treatment, or combined with some Chinese herbal antiviral preparations for treatment. (2) Use commonly used drugs for prevention. Lactating sows: antibiotics can be added to sow feed for 1 week before and after farrowing, with 400 grams of "Jiakang" added per ton of feed for prevention; or "Tiamulin" 100 ppm/ton + chlortetracycline 300 ppm/ton added, to reduce the contamination of the farrowing house by pathogens excreted by sows, cut off horizontal transmission of disease from sows to piglets, persist in prevention being more important than treatment, and ensure the health of "mother and offspring." Lactating piglets: at 21 days of age, lactating piglets are injected with long-acting oxytetracycline injections, such as "Dexamycin," "Aixuda," etc., to prevent the occurrence of digestive tract and respiratory tract diseases in suckling piglets. Weaned piglets: antibiotics are added to piglet feed from 1 week before weaning to 4 weeks after weaning. Use "Jiakang" added at 300 to 400 grams per ton of feed, or "Tiamulin" 100 ppm + chlortetracycline 300 ppm/ton added, or "Junkang" (clindamycin + spectinomycin + immune enhancer) 1 to 2 kg/ton, to cut off horizontal transmission of disease among piglets and piglets, with obvious effects on preventing various bacterial diseases and mycoplasma. The above drugs can be used in rotation, and each drug can be used for 2 to 3 months. Growing-finishing period: use effective drugs for prevention at 12 to 13 weeks of age and 17 to 18 weeks of age, but avoid using drugs that produce false positives for clenbuterol hydrochloride. "Jiakang" may be added at 300 to 400 grams per ton of feed, or "Junkang" 1 kg/ton, using pulse medication, for 1 week continuously, then stop for 1 week, then use for another 1 week. Replacement pigs: add drugs to replacement pig feed to cleanse pathogens in the body. 100 ppm tiamulin and 300 ppm chlortetracycline (100 mg doxycycline)/kg feed, or "Jiakang" added at 200 to 300 grams per ton of feed, one week each month, until mating.