During autumn and winter and at seasonal transitions, coughing and labored breathing are common problems on pig farms. Many farmers hear pigs coughing or breathing with abdominal effort and immediately use antibiotics. Sometimes they work; other times, the more treatment is given, the more deaths occur. The core reason is failure to identify the underlying cause. Coughing and labored breathing are symptoms, not diseases in themselves. Different triggers require very different prevention and control approaches and medication plans.
Pig coughing and labored breathing can be broadly divided into three categories: bacterial, viral, and environment-induced stress. In clinical practice, assessment should take into account the speed of onset, the condition of the herd, the season when the disease occurs, and anatomical changes.
Common causes of bacterial coughing and labored breathing include mycoplasmal pneumonia, Haemophilus parasuis, infectious pleuropneumonia, and Pasteurella. Mycoplasma, also known as enzootic pneumonia, is the most common. The disease course tends to be long, and pigs mainly have a dry cough. Coughing is more noticeable in the morning and evening, when pigs are being moved, and when temperatures drop. Their feed and water intake is generally normal, but growth slows, the feed-to-meat ratio increases, and the condition tends to recur. Infectious pleuropneumonia has a rapid onset and can cause open-mouth breathing, a dog-sitting posture, and foam around the mouth and nose; acute cases can result in rapid death. Haemophilus parasuis is seen mainly in piglets around weaning; coughing and labored breathing are accompanied by swollen joints, weight loss, and a rough, disheveled coat, and are more common in weaker piglets. Bacterial coughing and labored breathing tend to break out when stocking density is high, ventilation is poor, and temperature fluctuations are large, and can readily lead to secondary mixed infections.
Viral coughing and labored breathing, mainly associated with PRRS, PCV, influenza, and pseudorabies. Influenza spreads the fastest: the entire herd develops symptoms in succession over a short period, accompanied by fever, runny noses, increased eye discharge, and a marked drop in feed intake. Conditions generally begin to stabilize gradually after about 7 days, but secondary bacterial infections are very likely, leading to increased losses. Coughing and labored breathing caused by PRRS are often accompanied by sow abortions, many weak piglets, recurrent fever and weight loss in nursery pigs, and a relatively high mortality rate. PCV often occurs as a coinfection with Mycoplasma and Haemophilus parasuis, causing coughing, labored breathing, and progressive weight loss in pigs and resulting in runts. Antibiotics alone have limited effectiveness against viral coughing and labored breathing. The focus is on basic immunization, maintaining herd stability, and reducing secondary infections.
Environmental stress-related coughing and labored breathing are easily overlooked on many pig farms. Excessive ammonia or hydrogen sulfide in pig housing, high dust levels, direct drafts, large day-to-night temperature fluctuations, and unsuitable humidity can all irritate the respiratory mucosa and trigger protective coughing in pigs. This type of coughing and labored breathing is generally not accompanied by obvious fever, and coughing will ease noticeably once the environment is improved. If left unaddressed for a long time, the respiratory mucosal barrier remains damaged, making it easier for bacteria and viruses to invade and gradually turning the condition into pathological coughing and labored breathing.
To manage coughing and labored breathing effectively, do not rely solely on injections and medication. Follow the approach: “environment first, immunity as the foundation, management in support, and targeted medication.”
First, improve the pig housing environment. Balance temperature control with ventilation, avoid drafts, remove manure promptly, and reduce harmful gases and dust inside the housing. Control stocking density appropriately to reduce transmission through contact between pigs and lessen irritation of the respiratory mucosa.
Second, establish a solid foundation of immunity. Based on the strains present in this herd, follow standardized vaccination programs for PRRS, pseudorabies, circovirus, influenza, and other diseases. Stabilize baseline antibody levels in the herd and reduce the risk of viral outbreaks. Prioritize administering mycoplasma vaccines during the piglet stage to establish protection early and reduce long-term carriage and recurrent coughing.
Third, manage pigs in groups and identify and isolate sick animals early. Inspect the pens daily and promptly separate pigs showing coughing, abdominal breathing, or weight loss for individual isolation and care, preventing pathogens from continuing to spread through the larger group. Avoid frequent mixing or moving of groups to reduce stress-induced coughing and wheezing.
Fourth, use medication based on the diagnosis and avoid indiscriminate treatment. For stress-induced coughing and wheezing, prioritize environmental adjustments; large amounts of antibiotics are not needed. For bacterial coughing and wheezing, select sensitive medications based on the pathogen and use them for the full course; do not stop as soon as the pigs improve. For viral coughing and wheezing, focus on reducing fever, stabilizing metabolism, and preventing secondary infections, relying primarily on the animals’ own antibodies for recovery.
A final reminder: respiratory diseases are especially prone to mixed infections. Difficult-to-treat coughing and wheezing on many pig farms are not caused by a single pathogen; they often result from a combination of viruses + bacteria + environmental stress. Practicing good biosecurity, reducing the introduction of external pathogens, and managing the herd carefully can reduce the likelihood of recurrent coughing and wheezing at its source, preserve herd survival rates, and lower medication costs.