Source: Michigan State University Extension, Jerad Jaborek
Lameness can be caused by a variety of reasons such as hairy heel warts, foot rot, laminitis, toe and sole ulcers, toe abscesses, hoof lesions, limb injuries, or joint infections.
Following bovine respiratory disease, lameness is the second most common cause of morbidity in feedlot cattle, according to the Canadian Journal of Animal Science. Lameness can be caused by a variety of reasons such as: digital dermatitis (hairy heel warts), foot rot, laminitis (founder), toe and sole ulcers, toe abscesses, hoof lesions, limb injuries, or joint infections. While recognized as the number one cause of lameness in dairy cattle raised in confinement, digital dermatitis has become increasingly prevalent in feedlot cattle. Unlike some other lameness conditions that can be caused by injury, digestive upsets, or other infections, digital dermatitis and foot rot are caused by bacterial infections to the skin tissue. Digital dermatitis can be recognized by a raw bright red lesion, or an off-white to black scabbed over lesion, possibly with hair-like growths and inflammation near the heel bulb of the hoof. It may spread to the inner tissue of the hoof that is responsible for new horn growth, known as the corium, if there is an opening that may have been caused by a sole ulcer, white line fracture, or deep hoof crack. Bacterial infiltration to the irritated skin leads to inflammation and pain in the hoof of the animal. According to the 2021 article “Impact of digital dermatitis on feedlot cattle behaviour”, by Applied Animal Behaviour Science, with increasing lesion severity, cattle spend a greater amount of time being inactive and spend less time ruminating. Increased pain may also cause the animal to redistribute its weight from the infected heel to the toes, which may lead to increased wear of the toes and cause other hoof issues such as toe and sole ulcers.
Various factors have been associated with the incidence of digital dermatitis in feedlot cattle such as animal weight, cattle type (dairy vs. beef), pen density, pen cleanliness, forage concentration in the diet, and season. According to the Canadian Journal of Animal Science, digital dermatitis infections have been associated with heavier cattle compared with lighter weight cattle. Typically, this means heavier cattle have spent a greater amount of time in the confines of the feedlot, which may increase their exposure to becoming infected by digital dermatitis. Cattle type has been recognized as a significant risk factor for lameness, with a greater percentage of Holstein steers being infected with digital dermatitis compared with beef steers. According to the Canadian Journal of Animal Science, some believe the increased risk for digital dermatitis in feedlot cattle may stem from the origin of dairy calves in the feedlot as digital dermatitis is more common in dairy cow herds compared with beef cow herds. In another study published by the Canadian Journal of Animal Science about Alberta feedlots, digital dermatitis was most common during the winter and spring months. While cattle in this study were heavier in the spring as they approached market ready weights, pen conditions were wetter due to snow melting and rain. According to Translational Animal Science, pen conditions have been recognized as a risk factor for the incidence of digital dermatitis, as pens with excessive mud or more mud than bedding had a greater infection rate of digital dermatitis compared with dry pens or pens with more bedding than mud. Factors such as previous precipitation and elevated temperatures can cause pens to become wetter from rain, snow, or urine excretion. Wetter pens may lead to softer skin tissue around the hoof heel, thus increasing animal’s susceptibility to a digital dermatitis infection.
Treatment and Prevention
Digital dermatitis has been recognized since 1974, however, its cause is still being determined. The effects of digital dermatitis are known to regress after treatment with antibiotics, therefore suggesting the infections are caused by bacteria. An article featured in mSystems, determined that digital dermatitis lesions contain a combination of multiple bacterial species including Treponema, Mycoplasma, Porphyromonas, and Fusobacterium. Past efforts to vaccinate against digital dermatitis have proved ineffective. However, with these new findings, maybe an effective vaccine will be developed in the near future. Topical antibiotics are the most common method used to treat digital dermatitis by veterinarians and hoof trimmers, with systemic antibiotics used less because of their cost and label use. At the herd level, copper sulfate footbaths are commonly used to control digital dermatitis, but it does not necessarily prevent new or reinfection from occurring. Footbath management is extremely important for it to be advantageous at controlling digital dermatitis. Strategies that focus on the timing of footbath use, such as footbath implementation upon arrival or initial processing of newly received cattle, are also important considerations. To ensure effective use, the footbath must contain the recommended concentration of active ingredient (e.g., copper sulfate), be the appropriate pH, have minimal fecal contamination, and all feet must come in contact with the solution. According to the 2017 article “Evaluation of the prevalence of digital dermatitis and the effects on performance in beef feedlot cattle under organic trace mineral supplementation”, by the Journal of Animal Science, supplementing trace minerals for the control of digital dermatitis in feedlot cattle has also been investigated but has shown mixed results regarding its effectiveness.
Economic Impact of Digital Dermatitis
The prevalence of lameness in feedlot cattle has been reported to range from near non-existent to approximately 40% of the herd for feedlot operations was reported in the Canadian Journal of Animal Science. According to a 2021 article “Economic impact of digital dermatitis, foot rot, and bovine respiratory disease in feedlot cattle”, by Translational Animal Science, digital dermatitis can cause a reduction in average daily gain (0.18 to 0.37 lb./d) and final body weight (22 to 58 lb.). At the current market price for fed cattle in the U.S. ($1.37/lb.), that body weight loss represents an economic loss of $30 to $80 per head without accounting for the potential cost of treatments. Digital dermatitis can be a serious concern for many feedlot operations. Take precautionary steps to implement strategies to mitigate and control the incidence of digital dermatitis in your cattle herd. The best recommendations are to maintain clean, dry, and well bedded pens and use a footbath in herds with a greater prevalence rate.