Digital Dermatitis Isn’t Just a Dairy Herd Problem
Digital dermatitis (DD), also known as hairy heel warts, was discovered in 1974 in Italy. The disease first popped up in US dairy herds in the 1980’s, and spread rapidly during the 1990’s as herds expanded. The co-mingling of multiple dairy herds into one barn or facility made a perfect scenario for DD to infect millions of cattle.
Digital dermatitis is an incurable disease. Once cattle are infected with DD, they have it for life. Digital dermatitis cannot be cured, only managed. Treponemes, a spiral-shaped bacteria, cause DD. Treponemes that cause DD enter the body of an animal through a break in the skin on the foot. Treponemes hate oxygen and thrive in pen environments with poor hygiene, wet floor surfaces, and overcrowding. When cattle are subjected to standing in mud or manure for prolonged amounts of time, softening of the skin occurs and allows treponemes to penetrate the skin.
Digital dermatitis lesions mainly occur on the back feet. Lesions can spread between the toes and sometimes appear on the front of the foot. Lesions are recognized by two different appearances. One type of lesion, hyperkeratotic, appears as a raised callous. Proliferative lesions appear to have long fibrous hairs. Active DD lesions may appear initially as a raw, red, oval ulcer on the back of the heel just above or at the coronary band. There are six stages of DD. Named after one of the researchers who discovered DD, (Mortellaro), “M” stages are categorized as M0 (no lesion, healthy foot), M1 beginning of a lesion, M2 active, M3 healing, M4 nonactive healed lesion, and M4.1 nonactive healed lesion with an active M2 on top of a healed lesion.
Beef herds are not immune to DD. While DD is present in beef cow/calf herds, feedlot cattle are especially susceptible. The key to controlling DD is to prevent outbreaks and spread of the disease. Once you find it, you are too late, your herd is infected. Cattle who are co-mingled with other groups of cattle, transition cattle, and animals under stress are at highest risk of contracting the disease. Untreated DD can cause lameness resulting in decreased rate of gain in feedlot animals, and reduced fertility and milk production in replacement cows. In addition, losses incurred through treatment costs, increased labor, and potential animal mortality are economically detrimental to the overall enterprise.
Digital dermatitis causing treponemes are spread through manure and mud. Keeping pens clean and dry as possible is a good start to prevent the spread of disease. Prompt treatment of active M2 lesions will reduce the spread of DD to other cattle and reduce the chance of the infected animal’s development of lameness. Treatment requires the lifting of the foot, cleaning of the lesion, and applying topical oxytetracyclin. Dr. Dörte Döpfer from the University of Wisconsin School of Veterinary Medicine recommends <2g of oxytetracyclin per treatment. M4 lesions are a reservoir for future outbreaks. Treponemes lie deep within the skin and can become active at any point. Running cattle through a footbath two to three times per week should keep the lesion in the chronic nonactive M4 stage. Depending on preference, a premix, formalin, or copper sulfate solution will serve as an antibacterial and hoof hardening solution. All footbath solutions have pros and cons, you can read more about footbath options at: https://fyi.uwex.edu/dairy/resources/animal-well-being-herd-health/
Early detection and treatment are important factors to controlling DD in the beef herd. Walking pens to detect DD is the first step of control. Utilizing an integrated management strategy of footbath use, hoof care, and footbath use will help control the spread of the disease. Not every animal exhibits the same symptoms and reacts the same to treatment, so utilizing a consistent control strategy is important. It is still unclear how much DD economically impacts the beef industry, but one thing is for certain, DD is here to stay.