Migratory Birds Could Cause Avian Influenza in Northwest Dairy Cattle

Apr 16, 2024

By Anna King 

Experts say they are not sure how the highly-pathogenic avian influenza is passed among dairy cattle yet, but birds and cattle mingle a lot more than you would think.

Perhaps it’s that wild birds, really hungry now as they migrate and come out of winter, are looking for an easy meal. Dairy cow feed includes corn, grains and supplements, which attract the hungry birds.

“Avian influenza is everywhere,” said Amber Itle, veterinarian for the Washington State Department of Agriculture. “Because it’s ubiquitous, we need to be considering the fact that the risk is in our backyard right now, always, everyday.”

Itle said birds will really start moving in the next few months. She said now is the time for farmers to further tighten biosecurity.

Cattle health and biosecurity

So far, bird flu has sickened about 10% of the dairy cattle in the herds that have gotten avian influenza across the United States. Experts say most cattle make a full recovery. In poultry, this same virus causes high mortality rates, but in dairy cattle that is not being reported.

Federal recommendations for biosecurity include: trying to deter birds from getting into barns or areas where there are cattle, managing the movements of cattle and isolating new animals for 21 days upon arrival, keeping all species of animals, such as poultry, pigs, cattle separate, and keeping cats, dogs and wildlife out of barns.

Bird flu in cattle background

So far, highly pathogenic avian influenza has sickened cattle in Idaho, New Mexico, Texas, Kansas, Ohio and Michigan. There have been no reports of sick cattle with bird flu in Washington or Oregon, those state agriculture officials said.

The U.S. Department of Agriculture and state officials are working together in several groups to better understand the disease transfer from birds to cattle and from cattle to people.

Much of the disease appears to be infecting the animals’ udders, with calves and male cattle not contracting the disease because they don’t have developed udders, Itle said.

Just one person in Texas has been confirmed to have gotten sick from cattle infected with the disease. One man's eyes got red after he was exposed to sick cattle. This is only the second known case of the virus transferring to humans, according to National Public Radio.

Still, much is unknown about the avian flu in cattle, how the disease is being transferred from bovine to bovine, and how it’s being spread to people.

In Texas, U.S. Department of Agriculture officials said they are finding bird flu and dead grackles, blackbirds and pigeons, which are difficult to keep out of dairy barns.

Bird flu also has sickened a lot of other animals across the world, including marine mammals in South America, and there is a reported mink farm outbreak in Europe, according to NPR.

What about the milk?

It’s standard practice to remove sick animals from the milking string in the nation’s dairies, Itle said. Sick animals tend not to give much milk anyway, she said.

The virus can be found in the milk of sick cows but the sick animals’ milk is disposed of. In addition, pasteurizing milk kills viruses and bacteria, making commercial milk safe to consume at this time, according to the USDA.

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