Buffalo Fly Dermatitis in Cows

Buffalo fly dermatitis is an inflammatory skin condition associated with repeated feeding by buffalo flies, Haematobia irritans exigua. These small blood-feeding flies spend most of their adult life on cattle and can bite many times each day. In susceptible animals, the bites do more than irritate. They can trigger intense skin inflammation, hair loss, crusting, and painful sores.

The condition is often called buffalo fly lesions or buffalo fly-associated dermatitis. Lesions commonly develop near the medial canthus of the eye, on the neck, shoulders, dewlap, and ventral abdomen. In some cattle, the reaction appears to be linked to hypersensitivity to fly saliva. In others, skin damage may also involve secondary bacteria or the filarial parasite Stephanofilaria carried with fly activity.

For many herds, this is more than a cosmetic issue. Heavy buffalo fly pressure can reduce comfort, feed efficiency, weight gain, milk production, and hide value. If your cattle are rubbing, carrying visible fly loads, or developing scabby sores during fly season, it is worth asking your vet to help confirm the cause and build a practical control plan.

The direct trigger is repeated feeding by buffalo flies. These flies are close relatives of horn flies and remain on cattle much of the time, leaving mainly to lay eggs in fresh manure. Both male and female flies feed on blood many times per day, which creates ongoing bite trauma and irritation.

Not every cow reacts the same way. Research suggests that some cattle develop a hypersensitive inflammatory response to buffalo fly antigens or saliva, which helps explain why one animal may develop severe sores while another in the same pasture has only mild irritation. Dark-coated cattle and animals in poorer condition may also attract more flies.

Buffalo fly dermatitis can become more severe when other factors are involved. Secondary bacterial infection, especially with skin-damaging bacteria, may worsen ulceration and crusting. In some regions, Stephanofilaria worms are also associated with buffalo fly lesions. Because several processes can overlap, your vet may approach the problem as a combination of fly control, skin care, and ruling out other causes of dermatitis.

Your vet usually starts with the pattern of lesions, the season, and the number of flies present on the animal. Buffalo flies are small, dark, blood-feeding flies with a forward-projecting proboscis, and they are often seen clustering on cattle rather than flying off like some other pests. Lesions near the inner eye, neck, shoulders, and ventral body during periods of fly pressure can strongly support the diagnosis.

A clinical diagnosis may be enough in straightforward cases, especially if lesions improve after effective fly control. Still, your vet may recommend additional testing when sores are severe, unusual, or not responding as expected. Depending on the case, that can include skin scrapings, cytology, bacterial sampling, or biopsy to look for parasites, infection, or other skin diseases.

This step is important because several conditions can mimic buffalo fly dermatitis. Ringworm, lice, mange, dermatophilosis, photosensitization, trauma, and some eye-area tumors or chronic wounds can look similar at first glance. If lesions are deep, rapidly worsening, or affecting only a few animals in an odd pattern, your vet may want a more complete workup before choosing treatment options.

Prevention works best when it starts before lesions become severe. The goal is not only to kill flies, but to lower overall fly pressure in a way that slows resistance and protects the most sensitive cattle. Integrated control is the key idea. That means combining chemical and non-chemical tools instead of relying on one product all season.

Work with your vet to choose a herd plan that fits your region and production system. Options may include timely use of insecticidal ear tags, pour-ons, sprays, walk-through traps, and management steps that reduce breeding success in dung. In areas where buffalo flies are seasonal, quarantine treatment of incoming cattle may help prevent introducing flies to a herd. Product timing matters, and overuse can speed resistance.

It also helps to identify the cattle that repeatedly develop lesions. Some animals are more susceptible than others, and dark-coated or poor-condition cattle may attract more flies. Keeping records on which animals carry the heaviest fly loads or develop sores each year can help guide breeding, culling, and treatment timing.

See your vet immediately if lesions are deep, infected, near the eye, or attracting more flies. Early intervention is often the difference between a short seasonal skin problem and a chronic hide-damaging wound.