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Herd and Employee Health | May/June 2024

By Sarah Hill

Tips for safeguarding animals and people from taking a hit from Highly Pathogenic Avian Influenza.

With multiple dairy herds across the U.S. having been affected by an infectious disease, beef producers are on alert to ensure that their herds stay healthy. Highly Pathogenic Avian Influenza (HPAI) has been identified and is connected to the rash of illnesses, according to Joe Armstrong, DVM and University of Minnesota Cattle Production Systems Educator. As of print date, the pathogen has not officially been found among any beef herds.

Clinical symptoms, including drop in milk production, decreased feed consumption and rumen motility and tacky manure, compelled dairy herd owners to engage in diagnostic testing, which identified the H5N1 virus in the raw milk of affected cows, according to Dr. Katie Cornille, DVM, MPH, with the Minnesota Board of Animal Health.

“This virus is not something we routinely conduct surveillance for in cattle,” she added. “We don’t know if the disease is the cause of the clinical signs or if it’s a secondary or opportunistic infection along with another pathogen.”

The most impacted population among dairy herds has been mid- to late lactation cows. Armstrong notes that most beef cattle right now are dry or newly fresh - the two groups that haven’t been as impacted by HPAI.

“Dairy cattle are also under a lot more metabolic stress than beef cattle,” he said. “I would be surprised if it’s not already amongst beef cattle, and we just haven’t seen it clinically or widespread enough across herds to know to test for it.”

Keeping Cattle Healthy

Cattle producers should continue utilizing biosecurity measures to keep their herds healthy, according to Cornille, such as keeping new animals separate for three weeks to a month after purchase.

“If beef producers own multiple species of livestock, they should be housed away from cattle,” she said. “Keep feed and water protected from wildlife and contact the Department of Natural Resources if you find a lot of dead wildlife, including birds, on your property. If you have to touch any dead animals, wear disposable gloves.”

Keeping the herd up to date on recommended vaccinations is also one way to maintain overall animal health. Doing so will prepare an animal’s immune system to be ready to fight off any other organisms or infections, according to Cornille. Armstrong also recommends minimizing stress as much as possible. Gabriele Maier, Assistant Professor of Cooperative Extension, University of California-Davis School of Veterinary Medicine, agreed, adding that cows on a solid nutritional plane are healthier.

In dairy cattle, HPAI has caused symptoms including lack of milk production, lethargy, mild fevers, and in some cases, diarrhea, according to Armstrong. “The severity of their symptoms depends on how much virus load the cow receives,” he said. “But as we move into pasture grazing season, beef cattle will have more opportunity to interact with wildlife, which are a potential source of the virus.”

Beef herds tend to rely on surface water as a water source, which creates a prime spot for wild birds and other wildlife to share space and germs. On dairies where HPAI has been found, there have also been reports of deceased birds and sick cats, but it’s still unknown if those other species were sick or died due to HPAI.

Cats affected by the pathogen may show neurological signs, such as circling, being aggressive, or other abnormal behavior, Maier said. Armstrong said that it’s possible that HPAI is spread between cows, but that hasn’t yet been confirmed.

Cattle producers should also consider reducing food sources for wild birds, securing buildings, repairing holes in barn walls, and covering waste to discourage wild birds from gathering, according to Maier. “Cattle don’t live in a sterile environment, so they can’t be completely protected from birds,” she said.

Because beef cattle metabolic health is not monitored as closely as that of dairy cattle, any mild symptoms of HPAI may not be detected quickly in a beef herd. There are currently no vaccines available for HPAI and developing a vaccine can take months.

“Beef producers should look for sluggish cows or sick calves from the mother cow not producing any milk,” Armstrong said. “I always tell producers that if calves are sick, check the momma cow’s udder, because she may be the reason the calf is sick.”

Hungry, bawling calves may be the first sign that something is wrong, Maier adds. She encourages beef producers that if they suspect HPAI within their herd to immediately isolate any sick cattle from other animals and contact their veterinarian.

“As with all new diseases, we want to understand it better, and we can’t do that if cases are swept under the rug,” she said. “It may be inconvenient at the moment for a producer to engage with regulatory officials in an outbreak investigation, but it’s very helpful to the industry.”

Protect People, Too

“It’s important to remember that we do have a confirmed case of a human being infected with HPAI,” Armstrong said. “Although that case wasn’t severe, we can’t be sure of people’s immune status - including those who may or may not have anyone to advocate for them. We depend on our employees a lot and keeping them healthy is a major priority.”

Maier reminds cattlemen of general biosecurity measures, as outlined in the Beef Quality Assurance training. “Keep a visitor log, and don’t let people into areas where animals are that don’t need to be there,” she said.

Armstrong reiterated that so far, no muscle tissue has tested positive for HPAI, so the U.S. beef supply remains safe and healthy for consumers. However, per the Food and Drug Administration guidelines, unpasteurized milk and dairy products should be avoided, but pasteurized products remain safe.

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