Vets Tackle H5N1 In Dairy Mystery

The ongoing spread of High Path Avian Influenza in dairy cattle has been a puzzle for veterinarians to diagnose.

Dr. Barb Petersen of Amarillo, Texas, was featured on Market to Market in 2016. She saw early symptoms of H5N1 in some of the dairy herds she services earlier this year. But she and colleagues in Texas and New Mexico first pursued regular dairy illnesses as the cause of the symptoms. 

Dr. Barbara Petersen: "So I got a call from a vet colleague, end of February. And the question was, are you seeing adult cows with pneumonia and or diarrhea? I said, no, I'm not. Let's talk through what's going on. We make a list of things we're going to try to rule in or rule out. So we worked on that list. And the following week I have a client that I worked together on with another veterinarian, and we had a lot of cows with mastitis, almost like a very thick, very yellow mastitis. That looks like colostrum, right. But these girls were not recently calved. They had been milking for a while. So we went down the mastitis rabbit hole together.” 

The illness in the herds was still a mystery until a worker noticed another clue.

Dr. Barbara Petersen: “Hey, I have a number of barn cats and half of them have died. And so then the alarm bells, you know, start going off into your herd because the dairy is close to that dairy. I had sampled birds that ended up being positive for H5N1. So still at this time, that wasn't that wasn't on my radar. It was like, gosh, there's got to be some type of toxicosis, right? Some type of toxin is maybe in the feed or in the water.”

Tissue and fluid samples from the dead cats were sent to labs for testing, and were negative for rabies. Then a veterinarian at Iowa State ran the samples for H5N1.

Dr. Barbara Petersen: “He said that the cats brains and their lungs were positive for Influenza A on PCR, and so was your milk. And I'm this is not connecting in my head at all. I said, What? Are you sure? What does that mean? And there are other folks at the same time reaching the same conclusion that weekend and early the next week. And so that, unfortunately, is the diagnosis of bird flu in cows for the first time in the United States.” 

Recent weeks have been spent treating and observing sick cows, and studying their path back to health.

Dr. Barbara Petersen: “Short term prognosis has been good, right? The herds that I care for and have helped to care for, it's been really positive. Cattle are not dying from this and just like us, when we get the flu right, your appetite goes down. So she starts to feel better. You know, she's going to eat again. And then after that, you know, her milk production will slowly start to come back. It's like we just need to figure out how it's transmitted because thankfully, there's there's states and there's places that don't have this right now and would like to keep it that way. And I would like that for their sake to keep it that way, too. But as far as active disease, for most of the folks that I get to work with that have had this that runs its course, you know, in about 2 to 3 weeks, and then after that, when she feels better, she eats more normally. And then after that, milk production resumes more slowly.” 

There are no approved antivirals for cattle on the market, so the current treatment for avian flu is fluids, rest, and time. This week, USDA called for mandatory testing before interstate movement of dairy cattle.  

Doctor Petersen credits dairies that have been willing to be the test cases as being critical to solving the mystery.

Dr. Barbara Petersen: “It's finding folks that they're like, yes, I want to know the answer because this helps my neighbors, it helps the industry. This helps me. It's being fortunate to work with people that are willing to let you, quote unquote, work the problem.”

Data from infected herds will develop the protocols for treatment and prevention of the disease in the coming months.

For Market to Market, I’m Peter Tubbs.