Strawberry foot rot can show up in cattle lots
December 28, 2016
Most stockmen are familiar with foot rot infections in cattle, but there is another type of hoof infection that is less common and more difficult to treat. Often considered to be a dairy problem, strawberry foot rot also occurs in beef cattle, especially when cattle are confined. It's much rarer in a pasture situation.
This foot disease is also called hairy heel warts, but the technical term is bovine digital dermatitis, according to Matt Miesner, Kansas State University. "This foot lameness is caused by a different type of pathogen, Treponema, which is a type of spirochete bacteria. The bacteria alone does not explain the disease pathogenesis, but this is the organism that we find in these lesions, most of the time," he said.
"These bacteria are normal inhabitants of cattle digestive tracts. Out in the environment they thrive best in wet, muddy conditions. Many aspects of this disease are still unclear, but large concentrations of bacteria in these environments, which also weaken the natural defenses of the feet by softening and abrading the skin, allow the infection to get started. The bacteria could be there, but you need a wet environment and a lot of mud for the infection to get started — and it is contagious. In a confined area we generally see more animals become infected after the first one. When you see a case or two, then you generally see a fair number of them," he said.
In the right environment, these bacteria can spread and stay quite active, infecting more animals. If an infected animal comes into a feedlot or backgrounding yard, the disease may spread through many animals.
“This disease does not respond as well to systemic antibiotics and they are not labeled for bovine digital dermatitis.”
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"The affect is painful, just like a typical foot rot, but this lameness is different. Foot rot usually causes swelling between the toes and some necrotic tissue. Strawberry foot rot infection is not necessarily between the toes but occurs more frequently in the back cleft between the heel bulbs. Most often it's on the backside of the heels. It appears as a reddened, roughened, ulcerated and irritated area. It eventually looks granular (like a strawberry) and is very painful. The animal stands with weight on the toe, with the heel up, trying to not put weight on the sore heel. In later stages the affected area may have long hair-like structures that grow out from the heel. This would be something to check for if the animal is very lame and you think you are just treating a routine foot rot," Miesner said.
This type of foot infection is more common in dairy than in beef cattle, but may appear when beef animals are in a contaminated environment. "I have not seen this disease in young calves, but there have been a fair number of outbreaks in feed yard cattle (backgrounded calves or feedlots). I've also seen this condition in bulls grouped in wet pens. In backgrounding calves or in a feedlot, pen checkers may be pulling lame cattle and treating them for foot rot, if they are not familiar with what strawberry foot rot looks like. Then they notice that these animals are not responding to antibiotics like a typical foot rot case," he says.
"If you investigate a bit farther, looking at the foot, you discover that it's strawberry foot rot. This disease is diagnosed with a biopsy of the lesion; the bacteria can be seen under a microscope," he said.
Treatment is different than for foot rot. "This disease does not respond as well to systemic antibiotics and they are not labeled for bovine digital dermatitis. We usually use formalin foot baths, thoroughly rinsing the feet with an intensive program to try to halt the infection and limit spread. We may use topical oxytetracycline spray or powder, and dry the foot. Moisture is what allows these bacteria to keep going," he explained.
TREATING INFECTED ANIMALS
Systemic antibiotics labeled for foot rot, even when given in large volume, are not effective for this infection, so local treatment is recommended. "Topical oxytetracycline and copper sulfate foot baths (or any disinfectant-type foot bath) work better. Affected animals need to be recognized early and pulled into a treatment pen. They should be treated daily for a few days. Continue to keep them isolated from the rest of the cattle as they start to recover," he said.
"We wrap or bandage the affected foot after the topical treatment with antibiotic. This not only helps dry it out, but keeps it from continuing to contaminate the pen. The bandage needs to be kept dry for a couple days, and removed/replaced if it becomes wet," Miesner said.
As the animal starts to recover, the ulcerated red, seeping area starts to dry up and get a proliferative hairy-looking surface. "This is where the term hairy heel wart comes from. By the time this starts to scar and scab over, looking crusty, you know it's healing. The animal also becomes more comfortable, placing more weight on the affected foot."
There are vaccines for strawberry foot rot. "These are sometimes used in dairy cattle or bulls that are housed in preparation for sales, but they haven't been as effective for prevention as hoped," he said. The best prevention is to keep cattle out of wet areas.
Once an area gets contaminated — such as a pen or confinement lot — it stays contaminated. If the ground has a chance to dry out thoroughly, however, you may not see the disease again in that pen the next wet season, especially if you scrape the pen. If you clean up all the mud and manure, to get rid of most of the organic matter and then let it dry out, this generally helps. Liming the pen after cleaning it may be counter-productive since creating an alkaline environment may be more desirable for the Treponema.
"Cattle tend to harbor this bacterium, but once it has an opportunity to cause a problem — via a scrape, crack or scratch and a moist environment — the infection gets going and can amplify. There's an increased concentration of this bug after you get the clinical disease, and more animals may develop the problem," Miesner explained. ❖