By Barry Whitworth, DVM
All cattle producers at some time will deal with a lame bull, cow, or calf. Bovine lameness is associated with lost production, reproductive inefficiency, premature culling, and increase cost due to treatment. Some producers assume that all lame cattle have foot rot and treat these animals with an antibiotic. This assumption has merit based on the most common infectious cause of lameness is foot rot. However, in a retrospective study conducted at Auburn University Large Animal Teaching Hospital (AULATH), noninfectious causes were the most common diagnosis of lameness in cattle and in this study digital dermatitis (DD) was the most common infectious cause of lameness. With more emphasis placed on judicious use of antibiotics, producers should be certain of the condition that they are treating. Administering an antibiotic because an animal is limping without investigating the cause is not considered appropriate therapy. A disease such as digital dermatitis does not respond to injectable antibiotics. Digital dermatitis requires a topical treatment for the best results.
Digital dermatitis was first described in confined dairy cattle in Italy in 1974. The first case of the disease in the United States was in dairy cattle in New York in 1980. Since then, it has become the leading cause of lameness in dairy cattle in the world. The disease has been increasingly diagnosed in feedlot cattle and in cow/calf operations.
The cause of DD is not fully understood. The environment, immune system, and multiple bacteria all play a part in this disease. Spirochete bacteria of the genus Treponema are commonly found with the disease. Other bacteria such as Porphyromonas, Fusobacterium, Dichelobacter, and others are also associated with the disease. Wet manure contaminated environments tend to favor the development of the disease. Young cattle seem to more likely to get the disease which may be indicative of immune suppression.
Digital dermatitis must be differentiated from foot rot or infection of the deeper structures of the foot. With foot rot, the foot will have symmetrical swelling and skin split between the toes along with a foul odor. If the problem is an infected joint, it will usually have asymmetrical swelling and no foul odor. Digital dermatitis tends to be in the hind legs.
Not all the animals will be lame with this disease. However, it is common to see animals with DD shift their weight to the least affected leg and rest toe of the infected leg on the ground. With DD, initially a circular red raised mass (strawberry like) will be found on the skin between the toes on the back side of the foot. This mass may form papilliform projections that make it appear like a wart. As the lesion progresses to ulcerative mass, it will erode the skin on the back side of the foot.
Learn more in the February issue of OKFR!