Respiratory Diseases in Pigs: Causes and Prevention
By Aaron Vet Farms Ltd
Respiratory diseases in pigs are among the most important health challenges facing pig farmers because they can reduce growth, increase feed costs, cause poor feed conversion, and, in severe cases, lead to death. Respiratory problems are often caused by a combination of infectious agents and farm-management factors rather than by one pathogen alone. This is commonly described as the Porcine Respiratory Disease Complex (PRDC).
For farmers in Uganda and other African pig-producing regions, good housing, ventilation, hygiene, biosecurity, vaccination programs and early veterinary intervention are essential for reducing respiratory disease in pigs.
Featured image suggestion: A clean, well-ventilated piggery with healthy growing pigs would be ideal for this article.
What Causes Respiratory Diseases in Pigs?
Respiratory diseases in pigs can be caused by viruses, bacteria, parasites and environmental or management problems. More than one factor may be present at the same time, making diagnosis and control more difficult.
Important infectious agents associated with respiratory disease include Mycoplasma hyopneumoniae, Actinobacillus pleuropneumoniae, Pasteurella multocida, porcine reproductive and respiratory syndrome virus (PRRSV), porcine respiratory coronavirus, influenza viruses and porcine circovirus type 2.
Poor farm management can make the situation worse. Overcrowding, poor ventilation, high ammonia levels, dust, sudden temperature changes, stress and mixing pigs from different sources can increase the risk of respiratory problems.
1. Enzootic Pneumonia
Enzootic pneumonia is a common respiratory disease caused primarily by Mycoplasma hyopneumoniae. Affected pigs may develop a persistent dry cough, reduced growth and poor feed efficiency. In some herds, infection can remain mild while still causing significant lung damage.
The disease can also make pigs more vulnerable to secondary bacterial infections, including infections involving Pasteurella multocida.
2. Porcine Pleuropneumonia
Porcine pleuropneumonia is a potentially severe bacterial disease associated with Actinobacillus pleuropneumoniae. Signs may include fever, loss of appetite, difficulty breathing, weakness and, in severe cases, sudden death.
Because severe cases can progress rapidly, farmers should seek veterinary assistance quickly when pigs develop serious breathing problems.
3. Viral Respiratory Diseases
Viruses such as PRRSV, influenza viruses and PCV2 can contribute to respiratory disease. Viral infections may also weaken pigs or interact with bacterial pathogens, producing more serious disease.
This is one reason why controlling respiratory disease requires more than simply treating coughing pigs with medication.
Common Signs of Respiratory Disease in Pigs
Farmers should monitor pigs every day and investigate unusual changes in health or behavior. Common warning signs include:
Persistent coughing or sneezing
Rapid or difficult breathing
Nasal discharge
Fever
Reduced appetite
Poor growth or weight loss
Lethargy and reluctance to move
Uneven growth within a group
Increased mortality in severe outbreaks
A dry, persistent cough is particularly associated with enzootic pneumonia, while severe pleuropneumonia can produce marked respiratory distress and sudden death.
How Can Farmers Prevent Respiratory Diseases in Pigs?
Prevention is usually more effective and less expensive than dealing with a serious disease outbreak. A good respiratory disease prevention program should combine several management practices.
Improve Pig Housing and Ventilation
Good ventilation is critical in a piggery. Fresh air helps reduce excess moisture, dust, ammonia and airborne contaminants. Poor ventilation can increase environmental microbial loads and contribute to respiratory disease.
Pig houses should be kept clean, dry and comfortable. Avoid strong drafts directly onto young pigs while ensuring that stale air can escape.
Avoid Overcrowding
Overcrowding increases stress and makes it easier for infectious organisms to spread between pigs. Give pigs adequate space according to their age and size, and avoid keeping too many animals in one pen. Population density is an important factor influencing the severity and economic impact of respiratory disease.
Maintain Strong Biosecurity
Biosecurity is one of the most important tools for preventing pig diseases. New pigs should be sourced carefully and isolated before joining the existing herd. Limit unnecessary visitors, clean and disinfect equipment, and avoid sharing contaminated tools between farms.
Ugandan research has highlighted the importance of housing, hygiene, biosecurity, isolation of sick pigs and control of contacts with outside pigs in reducing respiratory disease risks in smallholder pig systems.
Use All-In, All-Out Management
Where practical, pigs of similar age should be managed as groups. An all-in, all-out system allows an entire group to leave a pen before it is cleaned, disinfected and prepared for the next group. This can reduce the carryover of infectious organisms between groups.
Reduce Stress
Stress can weaken pigs’ ability to cope with infectious challenges. Avoid unnecessary mixing, rough handling, sudden feed changes and poor transport conditions. New pigs from different sources should not simply be mixed together without an appropriate health-management plan.
Follow a Veterinary Vaccination Program
Vaccines can help reduce the impact of certain respiratory diseases, but vaccination programs should be developed according to the diseases present or likely to occur on a particular farm. For example, vaccination against Mycoplasma hyopneumoniae can reduce clinical signs and lung lesions, but it does not necessarily prevent infection completely.
A veterinarian can help farmers develop an appropriate vaccination and herd-health program.
What Should Farmers Do When Pigs Start Coughing?
Do not assume that every cough requires the same treatment. Respiratory diseases can have different causes, and several pathogens may be involved at the same time. Accurate diagnosis is therefore important. Veterinary examination, laboratory testing and, where appropriate, postmortem examination can help identify the cause.
Farmers should avoid using antibiotics routinely or without professional guidance. The correct treatment depends on the cause, severity and health status of the herd. Antibiotics do not treat viral infections, and inappropriate antimicrobial use can contribute to resistance.
At Aaron Vet Farms Ltd, farmers can seek professional guidance on pig disease prevention, veterinary services, animal health management and farm biosecurity.
Final Thoughts
Respiratory diseases in pigs can quietly reduce farm profitability even when mortality is low. Chronic coughing, poor growth, reduced feed efficiency and recurring treatment expenses can have a major effect on the performance of a pig farm. Enzootic pneumonia and other respiratory diseases are best managed through a combination of good ventilation, proper stocking density, hygiene, biosecurity, vaccination, stress reduction and early veterinary diagnosis.
For pig farmers in Uganda, prevention should be part of everyday farm management rather than something introduced only after an outbreak occurs. Clean housing, healthy replacement stock, careful monitoring and professional veterinary support can help build a healthier and more productive pig herd.
Aaron Vet Farms Ltd is committed to supporting farmers with practical animal-health solutions, veterinary services and guidance for profitable livestock farming.