Prevention and Treatment Methods for Respiratory Diseases in the Late Nursery Stage of Pigs

The nursery stage is the most important period in the entire growth cycle of piglets from birth to market, and it is also the period when piglets have a fragile body and the lowest disease resistance, as well as the most difficult period to care for. Because it serves as a link between the past and the future, it is crucially important, so special attention must be paid to this period. In the early stage, piglets often face diarrhea problems after weaning; in the late stage, respiratory problems are more common. Especially since late autumn of last year, respiratory diseases have become increasingly complex and difficult to control, becoming the most troublesome problem for pig farm owners.

The common symptoms of respiratory diseases in the nursery stage are: sneezing, coughing, panting, mostly abdominal breathing, gradual emaciation, long and dull hair, pale skin, decreased feed intake, lying down frequently, unwillingness to move. Once obviously emaciated, treatment is often ineffective, and death is the usual outcome. In colder seasons, in order to keep the barn warm, ventilation is poor, air quality is bad, and the incidence of respiratory diseases is relatively high; in warmer seasons in spring and early summer, the air is fresher, but respiratory diseases still occur, most commonly as sporadic cases, and are relatively difficult to control. Based on the domestic situation, respiratory diseases are mostly caused by Mycoplasma infection, mixed with Pasteurella, Bordetella, Streptococcus, Actinobacillus pleuropneumoniae, Escherichia coli, etc. Some pig farms also have the possibility of pseudorabies virus, swine fever virus, and blue ear disease virus infection, or even circovirus (PCV) infection. On necropsy, the lesions are mostly pathological changes of pneumonia, pleuropneumonia, pericarditis, or even peritonitis. The apical lobe and cardiac lobe of the lungs show meat-like consolidation, and the dorsal side of the diaphragmatic lobe shows symmetric hemorrhage or ventral margin consolidation. In severe cases, the entire lung is consolidated with increased specific gravity, fibrinous exudation on the apical lobe, cardiac lobe, or diaphragmatic lobe, or fibrinous adhesion of the entire lung to the pleura, pulmonary interstitial edema, mottled appearance, and elasticity; pericardial effusion or adhesion of the pericardium to the heart; purulent fluid in the abdominal cavity or a purulent membrane on the surface around the liver. The incidence of this disease varies among pig farms. In winter, it is above 40% in high-incidence farms and around 15% in low-incidence farms; in warm seasons it is about 10-20%, but the mortality rate is relatively high. Once there is a relatively high incidence, the production status of pigs throughout the nursery stage will decline significantly, growth rate will slow down, feed conversion will decrease, marketing time will be delayed, and medication costs will increase. Therefore, to control this disease, medication must be administered early and prevention must be started early. The following measures are recommended:

1. Prevent early infection

1). For sows before and after farrowing, feed medication to, first, reduce the Mycoplasma content in the respiratory tract and reduce the chance of early Mycoplasma infection in piglets in the farrowing house; second, clear bacteria in the birth canal, such as Streptococcus, Escherichia coli, Salmonella, etc., to prevent early infection during farrowing. Commonly used medication protocols are:

80% tiamulin 125 g + doxycycline 100 g, or 80% tiamulin 125 g + 12% colistin sulfate 2000 g + sodium bicarbonate (baking soda) 1000 g, or 80% tiamulin 125 g + sulfisoxazole 500 g + TMP 100 g + sodium bicarbonate (baking soda) 1000 g, mixed into 1 ton of feed, and fed continuously for 1 week before farrowing and 1 week after farrowing.

2). From 14 days of age of piglets, administer sensitive drugs in drinking water or feed to control infection by Mycoplasma, Streptococcus, Pasteurella, etc.

Common protocols are as follows:

80% tiamulin 190 g + amoxicillin (pure powder) 150 g + 10% colistin sulfate 1000 g mixed into 1 ton of feed, fed continuously until feed change, or 100% tiamulin 100 g + amoxicillin 100 g added to 1 ton of water, with continuous drinking water for 1 week every other week, using "pulse" medication until feed change (about 35-40 days of age of piglets).

2. Continuous medication during the nursery stage to control mixed respiratory infections and reduce the appearance of emaciated piglets

Commonly used protocols are as follows:

80% tiamulin 100 g + doxycycline 150 g or amoxicillin 150 g, mixed into 1 ton of feed, and fed continuously until transfer to the growing-finishing barn.