ISU Bovine Digital Dermatitis team
Drs. John Coatney, Jan Shearer, Paul Plummer and Adam Krull

Seeking Answers to Cattle Lameness

For more than three decades, bovine digital dermatitis has had a significant impact on the dairy cattle industry in the United States with USDA estimates finding that upwards of 90 percent of the nation’s dairies infected.

In recent years however, the disease which is a leading cause of lameness and welfare concerns among dairy cattle has started to find its way into beef cattle lots. That recent spread is leading to continued research by a team of veterinarians from Iowa State University’s College of Veterinary Medicine.

“Our research team has long looked at this disease at the dairy cattle level, but now we’re starting to focus more energies on the problems in beef cattle lots,” said Dr. Paul Plummer, assistant professor of veterinary diagnostic and animal production medicine. “And while we’ve known about digital dermatitis for a number of years, little is known about what bacteria causes the disease and how it can be prevented.”

That may soon change thanks to “bacterial metegenomics,” a new research methodology which provides a direct determinant to see what bacteria is present in a sample based on DNA. Through this process, digital dermatitis lesions are sampled and the DNA is purified, allowing researchers to obtain a “census” of what bacteria are present and how many of each bacterial species exist.

“By comparing the results of these evaluations across a large number of lesion samples, we have developed a must better understanding of how these lesions become infected and progress through the disease process,” Plummer said.

Digital dermatitis, also known as “Strawberry Heel Warts” is caused by bacteria that infect the heels of the cow’s feet resulting in a painful lesion. This makes it difficult for the animal to walk normally. A vaccine has been used to treat the disease over the past 20 years, but has proven ineffective.

The dairy cattle industry treats digital dermatitis with foot bathes. The cows normally walk over the foot bathes on their way to the milking barn. That solution, however, won’t work in the increasingly infected beef cattle lots.

“There is no way that would be effective for beef cattle,” Plummer said. “You can’t make a whole herd of cows walk through a foot bath.”

Iowa State’s research, which has been funded by both industry and the USDA, has identified critical points on how the lesions develop.

“This has allowed us to know the critical time period to help us control the disease,” Plummer said.

Other findings of the Iowa State research team include:

  • Single treatments do not eliminate the lesions and only about 10 percent of the lesions are permanently eliminated. The rest returns months later and the research group is looking at how changes in early therapy could change this.
  • Since this is a relatively new disease to the beef cattle industry, producers don’t know how to treat the disease and the Iowa State group is looking at ways to produce effective treatments in beef feed lots.
  • Earlier detection of the lesions is critical in the eventual treatment of the disease.

“The outcomes of this research are having a significant and important impact on the health and welfare of dairy and beef cattle throughout the United States,” said Dr. Jan Shearer, veterinary extension specialist. “These new insights are allowing us to identify earlier lesions and to better understand how the disease is maintained and spread within cattle herds.

“This allows us to do a better job of treating and preventing lesions which ultimately results in improved animal health and greater productivity of the animals.

Besides Plummer and Shearer, members of the Iowa State research team include Dr. Pat Gorden, senior clinician, and Dr. Adam Krull, clinical microbiologist.

June 2016