The USDA, the FDA and the Centers for Disease Control and Prevention (CDC) jointly released a statement on March 25 confirming the identification of highly pathogenic avian influenza (HPAI) in dairy cattle in Texas and Kansas. This was the first detection of HPAI in dairy cattle and has since been found in cows in additional states.
What is HPAI?
HPAI is a type of influenza A virus that primarily affects birds. This virus and current outbreak in domestic poultry, H5N1, has been occurring for almost two years.
“That outbreak started in 2022 in the U.S., and it's unfortunately resulted in the depopulation of over 80 million commercial poultry birds in the U.S. It has also been identified in over 200 mammal cases, but this is the first time that the virus has been identified in cows,” says Dr. Fred Gingrich, veterinarian and executive director of the American Association of Bovine Practitioners (AABP). “We assume at this point this disease outbreak started in the Texas Panhandle region when the virus jumped from birds into cows. So we assume that cows were initially infected from birds – migratory birds and wild birds – that are very common on all different types of dairies around the U.S.”
Migrating waterfowl are believed to be the source of the infections in this instance per the USDA. There are also concerns that cows can not only get the virus from birds but possible cow-to-cow transmission as well.
“We cannot rule out cow-to-cow transmission yet,” Gingrich says. “How it spreads from cow to cow and whether it is from respiratory secretions, oral secretions, feces, urine or milk, we don’t know yet.”
What are the symptoms of this disease?
This virus can be detrimental to the poultry industry, causing high levels of mortality; however, this does not seem to be the case in dairy cattle.
“Primarily what dairies see in cows when herds become suspicious that they might be infected are a drop in appetite and cows quit eating. Dairies that have rumen activity monitors noticed that a lot of cows are flagged by the computer for having decreased ruminations. On physical exam, these cows will not have rumination,” Gingrich says. “So basically, the rumen quits working, they quit eating and then they drop in milk production.”
Most infected herds have reported stiff or tacky manure, but some herds report diarrhea. Also, infected herds that are aggressive at monitoring their cows have reported fever in the very beginning stages of the disease, but that has varied as well, Gingrich says.
“Most cases in a herd seem to peak at about two to five days, and it affects about 10 percent of the cows in the herd,” Gingrich says. “It also appears to only affect lactating animals right now. Older animals second lactation and greater are more severely affected, and it most commonly affects animals later in lactation, such as five months or more, but it has been seen all across different stages of lactation.”
Also, some milk from affected animals has a thick, yellow, colostrum-like appearance.
“The biggest impact of this disease on dairy farmers is the herd loses about 20 percent of milk production for two to three weeks,” Gingrich says. “The good news is it doesn't appear to cause mortalities like it does in birds and other mammals. Most cows get over it in two to three weeks.”
Is milk and meat safe to consume?
Gingrich says the virus appears to have an affinity for the udder in cows.
“It's a little different than it is in birds where it has an affinity for the respiratory and gastrointestinal tract. In cows, it seems to have an affinity for the udder,” Gingrich says. “We have some concerns that unpasteurized milk may contain this virus, so farmers need to be very cautious.”
According to the USDA, the FDA and the CDC, pasteurization deactivates the virus.
“It's the position of AABP that raw milk is not safe for human consumption, and this highlights that again,” Gingrich says. “You should not drink raw milk if you are on a dairy and the consuming public should not either. But the public should be confident that drinking milk or eating dairy products that have been pasteurized remains safe.”
Beef is also safe for human consumption if properly handled and cooked.
What should producers do to protect their cattle?
Gingrich’s advice for farms is to enhance basic biosecurity measures and review with employees and relevant personnel, as well as to work closely with their herd veterinarian to help alleviate risk.
“Number one, you want to try to decrease the amount of bird contamination of feed. I can understand that is incredibly difficult on a dairy because those birds are attracted to what we feed the cows and then their droppings get in the feed and that is likely a major source of infection for cattle. So disrupting birds as best you can,” Gingrich says. “Also, you have to understand that some migratory birds are protected federally. So you always need to be aware of that. You can certainly use noise devices, deterrents, ribbons and plastic hawks to disrupt roosting areas.”
Secondly, Gingrich advises to sanitize and clean water troughs daily and, thirdly, to limit nonessential visitors to the farm.
“You want to keep it to the employees and the people that service your farm such as the feed trucks, the milk truck, the veterinarian and nutritionist,” Gingrich says. “Make sure that it's only the essential visitors that are coming to your farm and that they're practicing good sanitation in and out methods from your farm.”
What should farms do if they suspect their cows are infected?
If farms identify signs in their cattle that fit the symptoms of the disease, Gingrich says the first thing producers should do is immediately call their veterinarian.
“I can't stress that enough. You don't want to hide this because you're scared. Everybody has some anxiety and concerns over this right now,” Gingrich says. “This is the first time this has happened in the dairy industry within the last 100 years, so you need to contact your veterinarian. Your veterinarian will then contact their state animal health official so they can get the right forms and directions for submitting samples to your state diagnostic lab for evaluation to determine if the cows are infected with the avian influenza virus.
“Another reason why this is important is we need to get samples so we can learn more about how this disease is affecting herds, as well as making sure that other dairies in the area know that there is an infected herd in their state,” Gingrich says. “Lastly, for you to implement biosecurity measures to make sure more animals as well as people aren’t put at risk of this disease.”
What are best practices for herds infected with the avian flu?
Again, Gingrich tells dairy producers the number one thing they need to do is call their veterinarian of record or prescribing veterinarian so they can help develop a treatment plan specific to the herd. Currently there are no vaccines, drugs or feed additives available for purchase to prevent infection.
“In general, there is no specific treatment for viruses,” Gingrich says. “You need to carefully monitor these animals for any secondary infections such as pneumonia or mastitis that have been reported. These can occur in the beginning, middle or end of the curve of this disease presence on the dairy.”
Some general treatments that could be incorporated while working with the herd veterinarian could include supportive therapy, such as treatment for fever or fluid therapy for dehydration.
“It is recommended that the animals that are showing signs are moved to a hospital pen. If the hospital gets overcrowded, you may have to put them in a separate pen just by themselves for a short period of time,” Gingrich says. “Again, we don't know how or 100 percent if it's transmitted from cow to cow, but it's just good practice to try to separate those animals from the rest of the herd.”
Another best practice Gingrich mentioned is milking the infected or separated cows last.
“Milk them last and then go through your milking system and pipeline sanitation, cleaning and disinfection procedure at the end of that shift because of the potential concerns that it can spread cow to cow in the parlor through milk transfer,” Gingrich says.
Because of the concerns that unpasteurized milk may contain the virus, Gingrich also recommends being cautious of waste milk and to not feed it to calves unless it is pasteurized or otherwise heat-treated to kill harmful bacteria and viruses, such as influenza, before being fed to other livestock.
“If you need to dump milk in some other fashion, make sure that is done appropriately and that you contact your state officials,” Gingrich says.
Individual states may quarantine herds, but right now, there are no animal movement restrictions from the government standpoint.
According to Gingrich, individual dairies report that some cows have to be culled due to being a long way from dry-off.
“They dry up and don't have any milk anymore, and it's just an economic decision that every dairy producer is familiar with that they may have to cull some animals,” Gingrich says. “Reports from herds that AABP has talked to their attending veterinarians indicate that producers are culling between 2 percent and 9 percent of the affected animals. So again, it's affecting 10 percent of the animals, and of those, less than 10 percent are culled. If you extrapolate that to a herd, then it's not a high degree of culling. Thankfully for this disease, most cows recover.”
