Dairy cattle producers looking to continue to move lactating dairy cows should be prepared to take proactive steps to limit the spread of the H5N1 virus in their herd.
How to do that was top of mind for those listening in on a webinar hosted by the University of Minnesota and the Minnesota Board of Animal Health on Friday, April 26.
Guidance was released Friday from the Animal and Plant Health Inspection Service related to a federal order to be enacted Monday, April 29, which requires mandatory testing prior to interstate movement of lactating dairy cattle and mandatory reporting of positive influenza A test results in livestock.
With just about an hour to review that guidance, Minnesota animal health professionals gathered to answer questions from dairy producers in the state. To this date, no positive cases of the H5N1 avian flu virus have been reported in Minnesota cattle.
The panel of experts were guided through the webinar by Minnesota Milk Executive Director Lucas Sjostrom. Answering questions were University of Minnesota veterinarian Dr. Joe Armstrong; Board of Animal Health senior veterinarian Dr. Katie Cornille; Department of Agriculture director of dairy and meat inspection Dr. Nicole Neeser; and U.S. Department of Health epidemiology field officer Dr. Stacy Holzbauer.
Some key takeaways from the talk were reminders to producers that a positive test results in a 30-day premise shutdown, meaning no interstate travel. That means positive testing lactating cows can still travel within the state, just not across state lines. Armstrong indicated that while it’s not always possible to isolate these cattle, it’s in the best interest of herd and public health to limit the spread as quickly as possible.
Producers should also be aware of each state's individual regulations beyond the federal order that they may be transporting these cattle.
New information continues to come almost daily about the virus now found in dairy cattle in nine states and 34 herds, including news on Thursday that one in five commercial milk samples tested in a nationwide survey contained particles of the H5N1 virus, according to the U.S. Food and Drug Administration.
What to look for?
If dairy cattle are showing signs of illness, including reduced milk production, reduced feed intake or lethargy, these are indicators of illness. Armstrong said in some cases the milk of an infected cow can look like colostrum.
“Some of the cattle have fevers,” Armstrong said. “Many of the cattle have clear nasal discharge as well. And they look just on and off. That is that overt clinical signs and those cattle that need to be pulled and treated with supportive care.”
How to test?
Armstrong spoke extensively on the methods of sampling as outlined within the order.
Samples are to be collected by an accredited veterinarian, or a state-licensed veterinarian, or a sample collector approved by the appropriate state animal health official.
Samples to be collected include milk/udder secretions from individual cows. Each quarter is sampled and combined into one sample for submission to the laboratory. Armstrong noted that in testing, it was found that sometimes only some of the udders showed a positive test; that’s why samples are to be taken from all quarters. Submissions must be between 3 to 10 millileters of milk per animal. Pooling of milk samples can be done only at the laboratory.
For groups/lots of 30 or fewer animals moving interstate, all animals being moved must be tested. If more than 30 animals are moving interstate, then only 30 animals total must be tested. Sample collection and testing must take place no more than seven days prior to interstate movement.
Armstrong responded to questions about the speed of testing and explained that a result can be expected in one to three days. Further testing can take an additional two days.
While tests are completed at no cost, shipping costs are not reimbursed. Responding to the need to overnight samples, Armstrong said that overnighting will help to speed up results and thereby give producers the answer they need faster; however, because the virus particles are not living, punctuality of delivery is not as important. Still, he recommends the samples be kept chilled in shipping to avoid spoilage of the milk samples.
What if your herd tests positive?
Laboratories and state veterinarians must report positive results of tests for influenza A in livestock effective April 29. Interstate travel requires a negative test as performed by an approved National Animal Health Laboratory Network laboratory.
Owners of herds in which dairy cattle test positive will be required to provide epidemiological information, including animal movement tracing. Lactating dairy cattle from herds that have tested positive for influenza A are not eligible for interstate movement for 30 days from the most recent collection of any sample that tests positive from any individual animal in the herd. After the 30-day period, animals must be tested again for movement.
Armstrong commented that he believes the 30-day period could potentially be decreased in future guidance.
“There is ongoing research that will continue to challenge the 30-day movement stoppage to reduce this time if at all possible,” he wrote in response to a question. “Immune responses in individual cattle have been incredibly strong and fast, so this requirement of 30 days may change.”
One of his big concerns is that positive tests may continue to show up in milk samples despite no live virus being found, thus keeping some producer's cattle from moving for extended periods, though the risk of spread would seem very low.
Armstrong shared that among those testing positive, usually about 5% of the total herd is affected daily. Individual signs of symptoms may last three to five days. The herd is impacted for 14 to 21 days.
Those cattle that are showing signs of illness should get supportive care, Armstrong said. That looks like plenty of hydration and rumen support.
“That’s a lot of work, but that’s what needs to be done,” Armstrong said.
Cornille, with the Board of Animal Health, shared that the movement of dairy cattle should be limited right now, with or without positive testing. She also emphasized that animal record-keeping was important.
“Good, easily accessible records are going to help us help you,” Cornille said.
She shared that aside from the federal order, Minnesota movement requirements have not changed. Cattle imports in Minnesota require a Certificate of Veterinary Inspection, which means animals are examined by a veterinarian before they’re allowed to be transported and information on dairy cow importations are captured in real-time through the state's Traceability program.
Neeser, with the Minnesota Department of Agriculture, emphasized that pasteurization is effective at killing the virus but that milk that could contain a harmful substance is discarded.
She wanted to make dairy producers aware that if they are selling raw milk on their farms, milk from ill animals should be withheld for safety reasons. She added that if large amounts of milk needed to be discarded, to be considerate of nearby dairies so that this virus is not spread from the farm to others by machinery for example.
Holzbauer, with U.S. Public Health Service, emphasized the importance of wearing protective gear around dairy cattle including gloves, coveralls, eyewear and boots.
“We do want to protect those mucus membranes,” Holzbauer said.
It’s now been about a month since the second person in the U.S. was infected with the avian flu virus. At the time, the individual’s symptoms included pinkeye. That dairy worker is now fine.
Shelf-tested milk has tested positive for particulates of the H5N1 virus, but that does not mean the virus is spread through shelf milk because these are not living viruses after the pasteurization method. The Food and Drug Administration continues to say that pasteurized milk is safe to drink.
Holzbauer shared that the health risk to humans remains low. However, “it's constantly changing and we have to keep an open mind about influenza.”
“But really, the reality of influenza is that they're constantly pushing the envelope and they're constantly trying to see where they can go and what they can, in fact, and we've seen that with this virus. It's literally spread from the Arctic to the Antarctic and has spread to over 200 different mammals," Holzbauer said.
While no positive dairy infections have been reported in Minnesota to date, one high pathogenic avian influenza detection has been reported each month so far in 2024, for a total of four detections including three backyard flocks and one commercial flock.