Ringworm in Pigs: Fungal Skin Infection Signs & Treatment

Ringworm is a fungal infection of the skin and hair, also called dermatophytosis. In pigs, the organism most often involved is Microsporum nanum. Despite the name, there is no worm involved. The infection affects the outer layers of skin and hair shafts, which is why lesions often look dry, scaly, and circular.

In pigs, lesions often start as small bumps and then expand into ring-shaped patches with brown discoloration or crusting. These spots may spread outward over time. Adult pigs can have very mild disease, and some may seem only lightly affected even while they are still able to spread fungal spores.

For many otherwise healthy pigs, ringworm is not life-threatening and may be self-limiting over several weeks. Still, it matters because it can spread through a group, contaminate the environment, and infect people handling the pig. That makes early veterinary guidance and good hygiene especially important for pet pigs, show pigs, and multi-animal homes.

In pigs, ringworm is usually caused by the dermatophyte fungus Microsporum nanum. The fungus spreads through direct contact with an infected pig or indirectly through contaminated bedding, grooming tools, fencing, transport equipment, and housing surfaces. Fungal spores can persist in the environment, which is one reason outbreaks can keep cycling through a group.

Not every exposed pig develops visible disease. Age, stress, crowding, skin microtrauma, humidity, and overall hygiene can all affect whether infection takes hold. Young pigs and pigs in close-contact settings may be more likely to show lesions, while adults may carry milder or subclinical infections.

Because ringworm is zoonotic, people can also become infected after handling an affected pig or contaminated materials. Good handwashing, gloves during treatment, and careful cleaning of the pig's environment help lower the risk for both human and animal family members.

Your vet will start with a physical exam and a close look at the skin pattern, but ringworm can mimic other conditions. In pigs, common look-alikes include mange, bacterial skin infections, abrasions, and other causes of crusting or hair loss. That is why confirmation testing is helpful, especially if lesions are spreading or people in the home may be exposed.

To diagnose ringworm, your vet may collect hair and skin debris from the edge of a lesion for fungal culture, which is still an important confirmatory test. Culture can take days to weeks. Some practices may also use PCR testing for fungal DNA, which can be faster, though results still need interpretation in context. A Wood's lamp is less useful as a stand-alone test because not all dermatophyte species fluoresce.

Once your vet confirms or strongly suspects ringworm, they can help you choose a treatment plan that fits your pig's lesion severity, housing setup, number of exposed animals, and your household's zoonotic risk.

Prevention focuses on reducing exposure to fungal spores and catching skin changes early. Keep housing as clean and dry as possible, change bedding regularly, and avoid sharing brushes, blankets, halters, or transport equipment between pigs unless they have been thoroughly cleaned. If a new pig is joining the household or herd, a quarantine period and skin check can help limit spread.

If your pig has had ringworm before, environmental cleanup matters as much as skin treatment. Vacuum or remove loose hair, wash reusable items, and disinfect surfaces your pig contacts. Your vet can guide you on which disinfectants are appropriate for your setup and species. Gloves, handwashing, and dedicated clothing or footwear for pig care are smart steps when lesions are present.

Because ringworm can spread to people, prevention is especially important in homes with children, older adults, pregnant people, or anyone with a weakened immune system. If anyone develops a circular, red, scaly skin lesion after handling a pig with skin disease, contact a human healthcare professional promptly.