Multi-drug resistance to disease-causing bacteria is quickly becoming a complete “game changer” that could cripple the cattle industry’s ability to manage common bovine diseases.
“We are really slamming into the end of the antibiotic era,” said Dr. Trisha Dowling, a professor of veterinary pharmacology at the Western College of Veterinary Medicine.
“I’ve got 24 different drugs for the treatment of bovine respiratory disease, and it’s still the most economically significant disease problem when it comes to producing a pound of ground beef.
“The wimps, like bovine respiratory disease, they ain’t wimpy no more.”
In a recent study done at Kansas State, researchers found an increase in multi-drug resistance in one of the bacteria — Mannheimia haemolytica — that causes bovine respiratory disease in feedlot cattle.
“Those Mannheimia isolates are showing resistance across the spectrum of antibiotics we use in cattle,” said Dowling, who spoke at the UCVM Beef Cattle Conference in mid-June.
“In 2009, it was only five per cent. In 2011, it was 35 per cent. Now, it’s 70 per cent.”
Her warning was echoed by a senior official with the world’s largest producer of medicine and vaccinations for livestock and pets.
Multi-drug resistance isn’t just a problem with “a few of the big products” that the cattle industry uses, said Dr. Dorothy Erickson, manager of veterinary services at Zoetis.
“Every antibiotic that has ever been developed has eventually had some kind of resistance show up,” said Erickson. “This threatens to take us to a post-antibiotic era where we’re not able to treat common infections any longer. These common infections may become life threatening.
“It is a very real risk.”
Every dose of an antibiotic has a “consequence,” she said.
“The more we use these antibiotics, the more we are selecting to allow those resistant bacteria to survive in our animals and in the environment,” said Erickson. “The more resistance we see coming up in the future, the less effective our products are going to be at treating disease.”
Farmers may soon start to see some of the direct consequences.
“We’ll see increased costs on our operations from increased morbidity, illness, and mortality if our antibiotics aren’t working as well as they used to.”
But because of the linked resistance in different classes of antibiotics, banning the use of antibiotics isn’t going to be effective, said Dowling.
“It’s going to be like closing the barn door after the horse has left. That’s why we have to be so careful with the antibiotic tools that we still have.”
Up until now, antibiotics have been largely used as a “management tool,” but those days are coming to an end, said Dowling.
“That’s the kind of treatment that puts on the pressure for selecting for antimicrobial resistance,” she said. “We’re only going to be able to use them as an intervention.”
Erickson also said producers need to be more discriminating and use antibiotics “most effectively, where they’re most needed.”
“When we do deem it necessary to use these products, we need to make sure we’re using them correctly,” she said. “Do we have a diagnosis? And are we using the right product? We need to use the most appropriate product to target that specific disease.”
Using the correct dose is important, too.
“Both overdosing and underdosing an antibiotic will contribute to resistance,” said Erickson.
“We also need to be treating that animal for the appropriate amount of time — long enough that we’ve cleared up that infection, but not so long that we’re using those antibiotics unnecessarily.”
And as antimicrobials become less of an option, disease prevention will become even more critical.
“We as an industry need to start looking at alternatives to antibiotics and things that we can do a little bit better,” said Erickson.
Vaccination will be important, but biosecurity is “another huge one — how we manage our operations to avoid bringing disease in, in the first place.”
Stress reduction also plays a role.
“If an animal could do the exact same thing in the exact same spot every day of its life, it would be very happy. Cows enjoy routine,” said Erickson.
“Everything that we can do to keep that animal’s life the same is going to reduce that stress for them. Certain things like cattle handling and our management can help reduce those stresses and help prevent those diseases from getting in, in the first place.”
Ultimately, though, the cattle industry will need to present a “unified front” in order to protect the drugs used to treat common diseases like bovine respiratory disease, said Dowling. Without them, the cattle industry could be facing a crisis.
“In veterinary medicine, the discovery and development of these antibiotics have given us superpowers — but antimicrobial resistance is our kryptonite.”