Iowa State University veterinarians have uncovered new insight into the development of a foot disease in dairy cows that causes more lameness than any other malady. Bovine digital dermatitis, a disease that appears as painful lesions on the heel of a cow's hoof, has caused difficulty for the U.S. dairy industry for decades and has become a growing concern for beef producers as well, said Paul Plummer, an assistant professor of veterinary diagnostic and production animal medicine at Iowa State.
Plummer leads a group of researchers at the university's College of Veterinary Medicine studying digital dermatitis and potential treatments for its management. The researchers recently published an article in the peer-reviewed Journal of Dairy Science that takes a close look at the epidemiology of the disease, revealing new information on how the disease develops and how likely it is to recur after treatment.
"People have been researching this disease for 40 years, but we still don't understand its exact causes," Plummer said.
Veterinarians often link bovine digital dermatitis to a form of pathogenic bacteria known as treponemes because the bacteria are usually present in the advanced lesions caused by the disease. However, Plummer said the Iowa State research showed that treponemes don't appear during the earlier development of the disease, which suggests that other bacteria may drive the disease process and later create a favorable environment for the treponemes to thrive.
"The treponemes might be the rowdy guys causing problems at the end of the party, but they're not necessarily the ones who started the party," Plummer said.
Plummer and his team have studied 60 cows at the Iowa State Dairy Farm for three years, taking regular photos of the hooves of each animal to create a trail of data for each cow. When they found an animal with lesions caused by digital dermatitis, they went back through their photos and data to look for patterns in the early development of the disease.
The study also allowed them to catalog cases of recurrence after treatment and how often the disease resulted in lameness or immobility. The research showed that a majority of cows that contracted the disease weren't lame — a finding that has implications for how dairy and beef producers should track the disease.
"So, if you're only looking at specific occurrences of lameness in a herd, you may be missing a lot of cases," he said. "Just looking at lameness doesn't give a full picture of the disease."
Last year, Plummer and his team received a three-year, $500,000 grant from the U.S. Department of Agriculture to assess best practices for the treatment and management of digital dermatitis on farms and to study the disease on beef feedlots, where it's becoming more common.
Bovine digital dermatitis has largely affected the dairy industry, and dairy producers have managed the disease by installing walk-through footbaths between milking parlors and barns through which the cows travel before and after they're milked. However, in recent years, the disease has increasingly shown up in beef feedlots, where footbaths are less practical.
Plummer said it's unclear why beef cattle feedlots have recently developed more problems with digital dermatitis. Environmental contamination issues likely play a role, because feedlots tend to have persistent problems with the disease once cattle are infected, he said.
"Dairy farmers have learned to manage the disease and minimize lameness, but feedlots aren't equipped in the same way to do that," Plummer said. "Controlling the disease is a lot more difficult on the feedlots."
Genomic capital campaign
AgGenetics, a Nashville, Tenn.-based animal health and biotechnology company, has launched a $5 million equity financing campaign on AgFunder, an agriculture-focused online investment platform. The company uses cutting-edge biotechnology developed for human medicine to improve livestock health and productivity.
Using gene discovery and gene editing — modern biotech techniques initially developed for human medicine — AgGenetics is focused on technologies to help farmers combat common ailments that affect livestock production and increase the productivity of cattle. The company's defining feature has been its ability to identify the right genes in a timely fashion using genomic and data analysis approaches used infrequently in animal health.
AgGenetics currently has three products in late stages of development, including a low-cost test for brisket disease (also called bovine high-mountain disease), a copper deficiency and toxicity test and a new breed of heat-tolerant cattle. The technology is protected by more than 20 patent applications in countries around the world, including the U.S., Europe, Australia, Asia and South America.
Dr. Warren Gill, AgGenetics co-founder and chief executive officer, said the fund-raising "will help us get our first suite of products to market."
Dr. James West, co-founder and chief science officer, heads an independently funded laboratory at Vanderbilt University in Nashville and has been using data collection and analysis to identify genes for human medicine.
AgGenetics' first two products are its diagnostic test kits for copper deficiency/toxicity and for brisket disease, which have annual costs to the U.S. cattle industry of $2.8 billion and $130 million, respectively, Gill said.
Copper deficiency is one of the most prevalent nutritional issues for cattle, affecting about one-third of cattle. The deficiency has consequences for weight gain, fertility and milk yields, yet there is still no cost-effective, accurate and non-invasive procedure for detecting this condition.
Brisket disease affects about 5% of cattle at altitudes above 5,000 ft., causing them to suffer right heart failure, which leads to swelling in the chest from fluid retention.
Initial sales for both products are expected in the second quarter of 2017.