As the highly pathogenic avian influenza (HPAI) or bird flu continues to present challenges in dairy herds, the need for practical treatment strategies arises. This article walks through the critical first steps dairies should take when faced with a positive bulk tank test, common clinical signs to watch for, recommended treatment strategies and equipment to manage sick cows effectively.
Identifying clinical cows
The first strategy to being prepared for an outbreak in your herd is to work with your herd veterinarian to establish a plan now to identify clinical cows. Once your herd is infected, if you are unprepared, it will be overwhelming and hard to do the best you can for your animals in the moment. This will lead to more deaths, more abortions and more culls.
“If you get a positive bulk tank test, you need to implement your system screening for clinical cows as soon as possible because you don’t want to be missing them for two or three days when they could benefit from supportive therapies prior to that time,” says Maxwell Beal, a partner veterinarian at Mill Creek Veterinary Services Inc. in Visalia, California. “So my general advice is to identify clinical animals as quickly as possible.”
As the USDA continues national screenings of bulk tanks and tanker loads, they will identify infections in herds much earlier than producers will see clinical signs.
“With your first positive bulk tank test, you almost certainly will see clinical signs. Do not delude yourself into thinking that you will not see clinical signs, because they will hit you hard and they will hit you fast,” Beal says. “After a bulk tank comes up positive, you may be clinical the next day or, in my experience, it can take up to four weeks. Once clinical signs start showing up, a larger percentage of the dairy will likely become clinical within three to five days.”
The most consistent sign of infection that Beal saw was a high fever. Other symptoms included decreased dry matter intake, decreased milk production, abnormal milk that was thick and yellow, decreased cud chewing and rumination, labored breathing with runny noses as well as extreme depression and lethargy.
“I got into the mantra of telling my clients that infected cows look like cows that need to go down the road,” Beal says. “They won’t eat and they’ll look like cows that have a displaced abomasum (DA) but don’t have a DA. They’ll just sit there and won’t do anything.”
Another clinical symptom Beal saw somewhat consistently was abortions.
“You will see abortions to a varying degree – sometimes to a high degree. So don't be too alarmed and start spending a ton of money on diagnostics to find out what is causing it while you are in the midst of an outbreak of HPAI. Sometimes, those abortions will trickle out for months after you get it,” Beal says. “Pregnancy loss[es] seem to happen at any stage. So don't sleep on your dry cows and don't sleep on your heifers. Keep an eye on them to see if they are looking sick. Bird flu displays itself most profoundly in lactating animals, it’s true, but it is not exclusively a lactating animal disease. So pay attention to other animals that people may be saying aren't as affected, because in my experience it does affect them.”
Oral rehydration therapy
The second strategy to mitigating bird flu effectively is oral rehydration therapy.
“The biggest problem with bird flu is that animals become dehydrated and anorexic because they are not motivated to do anything,” Beal says. “It's not because of the disease per se that they're offloading a bunch of water. They're depressed, they don't want to get up, and they don't want to move. They sit there not eating or drinking, and they just dry out.”
Therefore, the most important thing a producer can do is support their cow’s hydration.
“Oral fluid replacement therapy I believe is the most practical, and I say easiest – acknowledging that it is not easy,” Beal says. “But I believe it is the most cost-effective and efficient way to do that.”
Beal suggested using standard, commercially available fresh cow drenches or making your own by consulting with your veterinarian and nutritionist for what should be added using bulk commodities. He recommends oral drenching Holstein cows with 6 gallons and Jerseys with 5 gallons once a day.
“Make sure you're using the correct dose. I think a lot of people shortchange it a little bit,” Beal says. “So work with your vet and come up with a dose and stick with it.”
To oral drench a large number of cows daily, Beal says one of the most efficient ways he saw clients accomplish this was by building homemade drenching rigs. These rigs are comprised of a large fluid storage tank, an agitation source to mix the drench, a pump that can drench at least 3 to 5 gallons per minute, a drench hose and flow meter to determine the amount given.
“Dairy producers around the country are very handy and seem to be able to come up with ways to create all sorts of things,” Beal says. “You need something that you can put a large amount of fluid into and something to agitate the fluid routinely because you don't want the drench mix settling so that you give one cow straight water and you give the next cow a dose of sea water. You want to hit 5 gallons per minute on your pump’s feed capacity and, when it’s not going to a cow, it’s defaulting to mixing the fluid. I think that’s the best and most efficient way I saw it done.”
If oral drenching is something a producer hasn’t done before but decides they want to do, Beal says they should get training and have someone there to help them learn how to do it correctly.
“The big thing is to get trained if you are uncomfortable with drenching. If you try to jump into doing 1,000 cows a day, you will drown and kill some, and you don’t want that,” Beal says. “There can be very long days but be patient when placing the tubes into the cows, and this will keep you from placing the hose into the trachea and depositing all the fluid in the lungs.”
For drenching administration, secure the cow’s head and open the mouth by putting pressure on the roof of the mouth. Slowly introduce the lubricated drench tube to the back of the mouth and allow the cow to swallow the tube. It is important to not force the tube. If the cow coughs while the tube is entering or if the tube is very easy to pass after the throat, it could be in the trachea.
“You want the tube to go pretty far down to the rumen,” Beal says. “We were using 5-foot tubes for Holstein cows. Some tubes will come with tape that marks off how far in you need to go.”
To make sure the tube is in the esophagus, Beal suggests checking the neck to feel for two rigid tubes. Normally, the trachea can only be felt with your hand. If your tube is in the right place, you will feel it in the esophagus. Because this can be difficult on mature cows, another suggested method for checking is by detaching the tube connection at a junction point on the hose and smelling the tube for “rumen” smell.
“Once you get the tube in the right spot, you can definitely give 5 or 6 gallons a minute no problem,” Beal says. “Afterward, I’m a fan of kinking the tube before you pull it out because it creates a vacuum that essentially holds the residual fluid in the tube when you’re pulling it out, so it doesn’t trickle into the trachea.”
Nonsteroidal anti-inflammatory therapy
The third treatment strategy Beal recommended is nonsteroidal anti-inflammatory therapy. These drugs can be used under the advice of your herd veterinarian to decrease pain, fever and overall improve how the animal feels.
“The FDA has said it is illegal for us to use aspirin in dairy cattle. So that’s my caveat. However, I do think there is benefit in nonsteroidal anti-inflammatory therapy,” Beal says. “So the other options would be to use flunixin products that various companies make that are on-label. They do have a withhold period, and it should be observed.”
Nonsteroidal anti-inflammatories should not be used without drenching or rehydration therapy.
“They can have pretty negative consequences for animals that are dehydrated,” Beal says. “Stomach ulcers, kidney failure and liver failure can happen by giving an acutely dehydrated animal a large dose of nonsteroidal anti-inflammatories, thus killing the cow.”
Goals of treatment
The main goals of treatment should be to support the cow’s normal systemic functions and fever reduction while the animal is sick to make them feel better so that they go back to eating, ruminating and ultimately return to normal milking.
“Don’t move cows unnecessarily if you are going to treat them and don’t take two hours to treat a pen. It’s not worth it if you’re going to take longer than an hour to treat a pen. If that means you’re not drenching because it’s taking too long, that’s OK. The biggest thing the cow needs is rest,” Beal says. “I asked all my clients, ‘What do you do when you have the flu?’ Most of the time when we are sick and have a fever, we want to sit in bed, relax, rest and maybe drink some water. The cows want rest too and don’t want to be locked up for two hours. Locking them up that long is only going to make things worse.”
So, Beal says to come up with a plan, stick to the plan to get it done and get them back to resting.
“Most dairy folks around the country work very hard, and this is another level of hard and is very stressful. So stay the course, be patient and do the best that you can. If something’s not working, don't be afraid to change it,” Beal says. “Keep in contact with the people who are there to help. Your vet might not be out there doing the work with you every single day, but if they're anything like most vets I know around here, they're available to help you. They know it's a crisis and they want to help you get through it, and that goes for pretty much all the support staff you have as well. So don't be afraid to lean on them, call them, ask them questions and see what they think about stuff as you're going through it.”
Ingredients a drench should include:
- Sodium
- Chloride
- Potassium
- Vitamin A
- Probiotics
- Calcium
- Energy source to help with energy balance – can add propylene glycol at 250 milliliters per cow per day
- Vitamin D, vitamin E, niacin, zinc and magnesium – all are beneficial but not expressly necessary
