Pulmonary Edema in Pigs

Pulmonary edema is a buildup of fluid in the lung tissue and air spaces. That fluid makes it much harder for a pig to move oxygen into the bloodstream, so breathing can become fast, noisy, shallow, or very labored. In practical terms, this is not a minor cough problem. It is a true respiratory emergency.

In pigs, pulmonary edema is usually a result of another serious problem rather than a disease by itself. One well-described swine cause is porcine pulmonary edema linked to fumonisin mycotoxins, toxins that can contaminate corn-based feed. Severe respiratory infections, aspiration of liquid or feed material, smoke or irritant exposure, and some heart or whole-body illnesses can also lead to fluid leaking into the lungs.

Because pigs can hide illness until they are very sick, a pig with pulmonary edema may look stable one moment and then worsen quickly. If your pig is breathing with effort, stretching the neck out, breathing open-mouthed, or showing blue-gray gums, your vet needs to assess them right away.

Pulmonary edema happens when fluid leaks from blood vessels into the lungs faster than the body can clear it. In pigs, one classic cause is fumonisin toxicosis, usually from contaminated corn or corn byproducts. Merck Veterinary Manual describes porcine pulmonary edema as an acute, often fatal syndrome in weanling or adult pigs, with dyspnea, cyanosis, weakness, recumbency, hydrothorax, and high death rates after several days of eating heavily contaminated feed.

Other causes are also possible. Severe pneumonia and porcine respiratory disease complex can damage lung tissue enough to impair normal fluid balance. Aspiration of liquid medication, feed, or stomach contents can inflame the lungs and lead to edema, especially if a pig has been force-fed, dosed too quickly, or has swallowing problems. Smoke, inhaled irritants, and major systemic illness can also injure the lungs.

Less commonly, heart disease or circulatory problems may contribute, especially in older or medically complex pigs. That is why your vet focuses on the underlying cause, not only the fluid itself. Two pigs can both have pulmonary edema but need very different treatment plans depending on whether the trigger is feed toxin exposure, infection, aspiration, or another emergency.

Diagnosis starts with stabilization. A pig in respiratory distress may need oxygen and minimal handling before a full workup, because stress can worsen oxygen shortage. Your vet will assess breathing pattern, gum color, temperature, heart rate, hydration, and lung sounds, then use the history to look for clues such as moldy feed, recent dosing by mouth, smoke exposure, herd illness, or sudden onset after a feed change.

Chest imaging is often the next step. Thoracic radiographs can help show fluid patterns in the lungs, while ultrasound may identify pleural fluid, surface lung consolidation, or other chest changes. Bloodwork may be used to assess oxygenation, inflammation, dehydration, and organ function. If infection is suspected, your vet may recommend respiratory sampling or, in herd settings, tissue submission to a diagnostic lab. Cornell notes that accurate diagnosis of porcine respiratory disease often requires tissue-based testing.

If fumonisin exposure is a concern, feed testing matters. Merck Veterinary Manual links acute porcine pulmonary edema to fumonisin-contaminated diets, and FDA guidance sets recommended maximum fumonisin levels for swine feed ingredients and complete feed. In some cases, diagnosis is confirmed by combining clinical signs, feed history, necropsy findings, and laboratory toxin analysis.

Prevention depends on reducing the risks that can injure the lungs. Feed safety is a big one. Store feed in a dry, clean area, rotate stock, and do not feed moldy corn, damp grain, or spoiled feed. If your pig develops sudden breathing distress after a new batch of feed, tell your vet immediately and save a sample for testing. FDA guidance provides recommended fumonisin limits for swine feed, and pigs are considered a sensitive species.

Good respiratory management also matters. Work with your vet on vaccination and herd-health planning when relevant, reduce overcrowding, improve ventilation, and limit dust and ammonia buildup. Promptly address coughing, fever, poor appetite, or reduced activity before a mild respiratory problem becomes a crisis.

Finally, be careful with anything given by mouth. Liquids should never be forced faster than a pig can swallow, because aspiration can trigger severe lung injury. During wildfire smoke or other poor-air-quality events, keep pigs in the cleanest air environment you can manage, reduce exertion, and contact your vet if breathing becomes noisy, fast, or difficult.