Ringworm on cattle appears as circular patches of hair loss covered with thick, grey, crusty scales. The lesions typically start small and expand outward, and the skin underneath may look red, inflamed, or moist when the crust is peeled away. It’s one of the most recognizable skin conditions in cattle, but the appearance changes significantly depending on the stage of infection and where it shows up on the animal’s body.
What the Lesions Look Like at Each Stage
Ringworm doesn’t appear overnight. After an animal is exposed to the fungus, there’s an incubation period of 7 to 14 days before anything is visible. The first noticeable signs show up between days 14 and 28: hairs break off close to the skin, leaving small, round bald patches. At this early stage, the spots may look like the animal simply rubbed the hair off on a fence post or feeder.
As the infection progresses, those bald patches become red and inflamed. The skin turns moist and begins producing scales and crusts made up of dead skin cells, dried fluid, and fungal material. By days 28 to 45, you’ll see the classic appearance: raised, grey or whitish crusts that feel rough and ashy to the touch. These crusty patches can range from the size of a coin to several inches across, and multiple lesions often cluster together.
Between days 45 and 60, the infection begins to regress on its own. The crusts dry out and fall off, revealing pink or reddened skin beneath. Because the fungus doesn’t destroy the hair follicle itself, new hair eventually grows back. The entire cycle from first signs to healing takes roughly 8 weeks, though severe cases can last longer.
Where Lesions Appear on the Body
The head and neck are the most common sites, but the exact location varies by age and sex. In calves, the most characteristic spots are around the eyes. These patches around the eye sockets are often the first thing a producer notices, though calves can develop widespread lesions across the body in severe cases.
Cows and heifers tend to develop ringworm on the chest and limbs. Bulls, on the other hand, are more likely to show lesions in the dewlap (the loose skin hanging below the neck) and the skin between the jaw bones. In any animal, severe infections can spread well beyond these typical areas and cover large portions of the body.
Severe Cases Look Different
Most ringworm cases are mild and relatively contained, but heavily affected animals tell a different story. Widespread crust formation can cover large areas of skin, and when those crusts are removed, the tissue underneath is often moist and hemorrhagic, meaning it bleeds easily. Animals with severe infections may also lose weight.
The bigger concern with advanced cases is secondary bacterial infection. The fungus damages the skin and hair follicles, creating an opening for bacteria to move in. When this happens, the lesions can become pus-filled, a condition called suppurative folliculitis. Instead of the typical dry, grey crusts, you may see oozing, yellowish discharge or lesions that look angrier and more swollen than standard ringworm. These cases need both antifungal and antibiotic treatment to resolve properly.
Calves Are Hit Hardest
Ringworm is common in cattle herds overall, but calves are far more susceptible than adults. In one study, 60% of calves aged 4 to 6 months were infected compared to 41% of calves under one month old. That age group carries roughly twice the risk of younger animals, likely because of the stress of weaning, rapid growth, and the immune challenges that come with both. Close confinement, nutritional deficiencies, and parasite burdens all weaken a calf’s ability to fight off the fungus.
Outbreaks tend to spike during winter months when cattle are housed indoors. Crowded conditions make animal-to-animal transmission easy, and the fungal spores survive well on wooden fences, feeders, and other surfaces that animals rub against.
How to Tell It Apart From Other Skin Conditions
Several cattle skin problems can mimic ringworm at first glance, so knowing the differences matters. Lice infestations typically cause hair loss and irritation along the backline, the top of the animal from neck to tail. Ringworm rarely concentrates there. Mange, caused by mites, tends to produce intense itching. Ringworm is notably non-itchy in cattle, which is one of the most useful distinguishing features. An animal with ringworm won’t be scratching and rubbing the way a mangy animal does.
Warble fly damage also shows up along the backline as raised lumps, which looks nothing like the flat, crusty patches of ringworm. If you’re unsure, a vet can examine broken hairs under a microscope to look for fungal spores clinging to the hair shaft, which confirms the diagnosis.
It Spreads to People
The fungus that causes cattle ringworm transfers readily to humans through direct skin contact with an infected animal or contaminated surfaces. Small cuts or scrapes on your hands and arms make transmission even easier. On human skin, the infection typically appears as oval, red, scaly patches that expand outward and clear in the center, forming the classic “ring” shape.
When the fungus affects the scalp or beard area, the infection can be more aggressive: a painful, swollen mass studded with pustules that ooze pus and dry into crusts. Hair within the affected area becomes loose and pulls out easily. Pressing on the swollen area causes pus to leak from multiple follicles at once. Lymph nodes behind the ears or at the back of the neck may swell. Wearing gloves when handling infected cattle and washing your hands and forearms thoroughly afterward reduces your risk significantly.