Hair loss in pigs has several possible causes, ranging from completely normal seasonal shedding to parasites, nutritional problems, and skin infections. The pattern of hair loss, your pig’s age, and any accompanying symptoms like itching or skin changes are the best clues to narrowing down what’s going on.
Seasonal Coat Blowing
If your pig is otherwise healthy and the hair loss is widespread, the most likely explanation is a normal process called “blowing coat.” Mini pigs and other domestic breeds shed all or most of their hair seasonally to make way for new growth. During a coat blow, a pig can lose every visible hair on its body, which understandably alarms owners who haven’t seen it before.
This process typically takes one week to a month from start to finish. New hairs usually start poking through the skin shortly after the old ones fall out, sometimes within days. If you look closely and see tiny bristles emerging, that’s a good sign the loss is just seasonal turnover. No treatment is needed. Coat blowing is healthy and happens at least once a year, often in spring or early summer.
Sarcoptic Mange
Mange is one of the most common medical causes of hair loss in pigs and the first thing to rule out if your pig is also itchy. It’s caused by microscopic mites that burrow into the skin, triggering intense scratching, flaking, and thickened, crusty patches. The front legs, ears, and torso are usually hit hardest. Over time, you may notice red lumps, scabs from scratching, and progressive hair loss in those areas. Severely affected pigs can become lethargic, lose weight, and run a mild fever.
Mange mites are invisible to the naked eye, so you won’t see the parasite itself. A vet can often confirm the diagnosis with a skin scraping. Treatment involves an antiparasitic medication given by injection, and because mite eggs can survive the first dose, a second treatment a few weeks later is sometimes necessary. Sows should ideally be treated before giving birth to prevent passing mites to piglets.
Lice
Pigs are affected by only one species of louse, a blood-sucking parasite roughly 6 millimeters long with a grayish-brown body and dark markings. Unlike mites, lice are large enough to see. Check the hidden spots first: inside and behind the ears, in neck folds, and in skin creases. Lice cause itching, rubbing, and patchy hair loss in the areas where they congregate.
One thing to know about lice treatment: the eggs (called nits) are not killed by most antiparasitic medications. Those eggs can take up to three weeks to hatch, so a single treatment may clear the adults but leave a new generation waiting. Retreatment after a few weeks catches the lice that hatch from surviving eggs.
Ringworm
Despite its name, ringworm isn’t a worm. It’s a fungal infection that lives on the skin and hair. In pigs, it shows up as circular patches of hair loss with crusty or scaly skin underneath, often red and itchy. The ring-shaped pattern is the classic giveaway, though not every case looks textbook.
Symptoms appear two to four weeks after exposure. Pigs pick up the fungal spores from direct contact with infected animals, contaminated brushes or equipment, or even soil. Ringworm is also contagious to humans, so if you notice circular, itchy patches on your own skin while your pig has similar lesions, that connection is worth mentioning to both your vet and your doctor.
Greasy Pig Disease
This bacterial skin condition mostly affects piglets and young weanlings. It’s caused by a type of staphylococcal bacteria that produces toxins attacking the outer layer of skin. The toxins break down the bonds holding skin cells together, destroying the skin’s barrier and leading to blistering, oily or greasy-looking crusts, and flaking that can spread across the entire body. Hair loss follows as the skin underneath becomes too damaged to support it.
Greasy pig disease tends to come on quickly and looks dramatic. The greasy, crusty appearance is distinctive and different from the dry flaking of mange or ringworm. Young pigs with developing immune systems are most vulnerable, particularly in environments where skin abrasions from rough flooring or fighting create entry points for the bacteria.
Zinc Deficiency
A nutritional cause worth considering, especially in growing pigs, is zinc deficiency. When zinc levels are too low relative to other minerals (particularly calcium), pigs develop a condition called parakeratosis. The skin becomes thickened, rough, and crusty, and hair loss follows. Growing males tend to show symptoms more severely and earlier than females of the same age, while adult breeding pigs may not show signs at all.
This problem isn’t always about too little zinc in the feed. Excess calcium can block zinc absorption, so even a diet with adequate zinc can cause deficiency if the mineral ratios are off. If you’ve recently changed your pig’s feed or are mixing your own ration, the balance of minerals is worth reviewing with a vet or livestock nutritionist.
Sunburn and Skin Damage
Light-skinned pigs and breeds with thin hair coats are especially vulnerable to sunburn. Mild sunburn causes generalized redness, but more serious burns lead to flaking, peeling skin, and hair loss in the damaged areas. Some pigs in acute pain will dip their back downward and squeal while walking, or even drop to their stomachs.
Repeated sun damage is more than a cosmetic concern. Damaged skin cells can become cancerous over time, and squamous cell carcinoma is a relatively common cancer type in pigs. It appears as raised masses or open sores on the skin. Providing shade and limiting midday sun exposure are the simplest preventive measures, especially for pink-skinned pigs.
Selenium Toxicity
While less common, excessive selenium in the diet causes a distinctive pattern of damage. Pigs with chronic selenium poisoning lose hair, develop necrotic (dead) patches on their skin, and show damage to the coronary band and hooves. Severe cases involve emaciation and liver damage. This typically happens when feed is accidentally supplemented with too much selenium or when pigs have access to selenium-accumulating plants. If you’re seeing hair loss combined with hoof problems, selenium toxicity is a possibility to investigate.
Stress and Behavioral Hair Loss
Pigs are intelligent, social animals that need mental stimulation. When they’re bored, overcrowded, or stressed by changes in their environment, they may develop repetitive behaviors like rubbing against surfaces, chewing on pen mates, or scratching excessively. All of these can cause mechanical hair loss, meaning the hair is physically pulled out or worn away rather than falling out from a skin problem.
Clues that the hair loss is behavioral include an otherwise healthy-looking pig with no skin crusting, redness, or parasites visible, and hair loss concentrated in areas the pig can reach by rubbing or that pen mates can reach by biting (flanks and tails are common targets). Environmental enrichment, more space, rooting materials, and reducing competition for food can all help. That said, itching from an undiagnosed medical cause like mange can mimic behavioral scratching, so it’s worth ruling out parasites before assuming the problem is purely stress-related.
Post-Farrowing Hair Loss in Sows
If your sow recently gave birth, the hair loss may be hormonal. The physical demands of pregnancy and nursing shift nutrient priorities away from hair maintenance, and many sows experience noticeable thinning or shedding after farrowing. This is similar to the postpartum hair loss that humans experience and typically resolves on its own as the sow recovers and her hormone levels stabilize. Ensuring adequate nutrition during lactation helps support regrowth.