Aflatoxicosis in Pigs: Moldy Feed and Liver Damage

Aflatoxicosis is poisoning caused by aflatoxins, a group of mycotoxins produced mainly by Aspergillus flavus and Aspergillus parasiticus. In pigs, these toxins most often enter the body through contaminated feed ingredients such as corn, grain by-products, or mixed rations. The liver is the primary organ affected, so pigs may develop liver inflammation, impaired clotting, poor growth, and in severe cases liver failure.

This problem can show up as a sudden outbreak or as a slower, harder-to-spot decline in herd health. Lower-level exposure may cause reduced feed intake, slower weight gain, weaker immune function, and poorer reproductive performance. Higher exposures can lead to depression, jaundice, bleeding problems, and death.

Young pigs and breeding animals are generally more vulnerable than heavier finishing pigs. Because signs can overlap with infectious disease, nutritional problems, or other toxins, your vet usually needs both pig-level information and feed-level testing to sort out what is happening.

Aflatoxicosis is caused by eating feed contaminated with aflatoxins. These toxins are produced by certain Aspergillus molds, especially in corn and other grains. Contamination can begin in the field, particularly during hot, dry growing conditions with insect damage, but extension and veterinary sources note that it often becomes a bigger problem during storage when moisture, heat, and poor aeration allow mold growth to continue.

Risk goes up when feed ingredients are damp, caked, dusty, bridged in bins, or stored in dirty equipment with leftover old feed. Ground feed can be especially vulnerable because it offers more surface area for fungal growth. Screenings and fines also carry higher risk and are generally poor choices for swine diets when mycotoxins are a concern.

Dose matters, but so do age and health status. Young pigs and breeding animals are less tolerant than heavier finishing pigs. Lower concentrations may reduce feed intake, growth, and immune function, while very high concentrations can cause severe liver injury and death. FDA action levels for aflatoxin in feed are stricter for immature animals and breeding swine than for finishing swine, which is one reason your vet and nutrition team may recommend different responses for different groups on the farm.

Diagnosis starts with the story. Your vet will ask when signs began, which groups are affected, whether there was a recent feed delivery or ration change, and whether the grain source, storage conditions, or weather history raise concern for mycotoxins. Because many diseases can also cause poor growth, jaundice, diarrhea, or sudden death, history alone is not enough.

The next step is usually a combination of pig testing and feed testing. Bloodwork may show evidence of liver injury, anemia, or clotting problems. Feed or grain samples should be collected carefully from multiple spots in the batch, then combined into a representative sample for laboratory analysis. Extension and diagnostic lab guidance emphasizes that poor sampling is a major reason mycotoxin testing can miss the problem.

If pigs die or are euthanized, necropsy can be very helpful. Your vet may submit liver and other tissues for histopathology and toxicology while also sending the suspect feed for a mycotoxin panel. Aflatoxin is often confirmed by linking compatible clinical signs and liver lesions with toxic levels found in the consumed feed. Your vet may also test for infectious diseases or other toxins, since mixed problems can happen at the same time.

Prevention starts with feed sourcing and storage. Buy grain and complete feed from suppliers with quality control programs, and be cautious during drought years or when corn quality is poor. Store feed cool and dry, protect it from leaks and condensation, and clean bins, augers, trucks, and feeders regularly so old material does not seed new batches with mold.

Moisture control matters. Extension guidance commonly recommends drying grain promptly and maintaining storage conditions that limit fungal growth. Watch for caking, bridging, heating, fines, and musty odor, but remember that feed can contain dangerous aflatoxin even when mold is not obvious. If a batch is questionable, isolate it and talk with your vet or diagnostic lab before feeding it.

Routine monitoring can save a lot of loss. Track feed intake, growth, reproductive performance, and unexplained illness by group. If you have repeated risk, your vet and nutrition team may suggest periodic mycotoxin screening and a feed management plan that includes careful ingredient rotation and, in some situations, approved binders or adsorbents.

Do not feed suspect grain to young pigs or breeding animals without veterinary and nutrition guidance. FDA action levels are lower for these groups because they are more vulnerable. Early testing and quick feed changes are often the most practical way to prevent widespread liver damage and herd setbacks.