Occasionally cattle react to a vaccine. An allergic reaction can be mild and local (swelling at the injection site) or serious and fatal. Dr. Andrew Niehaus, professor of farm animal surgery at Ohio State University, says vaccines contain specific antigens and their purpose is to stimulate a reaction so the immune system will respond and build antibodies to protect the animal later if exposed again to that disease antigen.

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Heather Smith Thomas is a freelance writer based in Idaho.

“Hopefully the reaction to the vaccine antigen will be mild and the animal never feels sick, but vaccine is designed to make the body react,” says Niehaus. “Ideally this will protect against the disease, and won’t create systemic signs of illness. When we vaccinate animals, however, some respond a bit differently and may have an obvious reaction.”

Dr. Tim Nickel, bovine technical services veterinarian with Boehringer Ingelheim, says the reason we give vaccines is to stimulate the immune system, but sometimes this results in hyper-stimulation, similar to people with allergies.

“Some cattle are just more sensitive to that particular antigen,” he says. “When we see severe reactions like anaphylaxis, this is due to hypersensitivity in that individual animal. There may be a genetic component. It may also involve environmental exposure, especially at a young age, as the immune system is developing.

“We generally don’t see more than one anaphylactic reaction in a herd unless there is a genetic component; in most cases it’s just a single animal.”


“In an anaphylactic reaction, all the body systems shut down,” says Niehaus. The animal has trouble breathing and suffers cardiovascular shock and low blood pressure. The animal may pass out and collapse and may die quickly.

“More commonly, a reaction produces local swelling and inflammation at the injection site. This can happen with any kind of injection. Many animals exhibit a local inflammatory response and often form scar tissue in that area (small knots or injection-site lesions). This is why we try to avoid giving injections in the rump or any other areas that will eventually be high-quality meat. Scar tissue can usually be trimmed out, but we prefer to have that problem in a place like the neck, where it doesn’t matter so much,” says Niehaus.

The most common vaccine reactions are due to the antigen itself, but can also be due to the carrier or adjuvant. Killed vaccines are most likely to cause reactions; they tend to be a little weaker at stimulating the immune system than a modified-live vaccine, so various carriers called adjuvants are added to help boost immune response and make the vaccine more effective.

“The adjuvant gives a little extra push, to achieve better immunity and protection,” says Nickel. “We probably saw more reactions to some of the older adjuvants than we see today, but we still see some reactions associated with these. Of the killed vaccines, most reactions occur with the clostridial products [7-way and 8-way vaccines],” he says.

Usually these reactions are just local swelling, rather than anaphylactic reactions. The animal is sensitive to the adjuvant.

“Often these vaccines have oil adjuvants that provide extra stimulation of the immune system. We may see a lump at the vaccination site, especially nowadays with beef quality assurance programs recommending to put it in the neck and administer it subcutaneously,” Nickel says.

Another problem that is not really a reaction is infection and/or abscess at the injection site. This can happen if the hide was dirty or a dirty needle was used but also tends to happen more commonly when certain types of vaccine are used.

“We see it most commonly with caseous lymphadenitis (CL) vaccines in goats, or Johne’s [disease] vaccine in cattle, where the disease itself is a granulomatous type of inflammation,” says Niehaus. “We may get a similar reaction at the injection site, such as a big granulomatous mass.”

If an animal does react adversely to a certain vaccine, keep records and make note of this individual, and consult with your veterinarian regarding future vaccination for this animal. If it experiences a second exposure to the same antigen, it may trigger a more severe (and possibly fatal) reaction.

“It’s also a good idea to contact the company that made the vaccine. They should be keeping records of any reported reactions,” says Niehaus. “Vaccines are always tested before they go to market, but the number of animals they test in clinical trials is nowhere near the number that will be getting the vaccine after people start using it. Knowing the true incidence of reactions [with large-scale use] is important for the companies to know.”

Treatment options

Local swelling and inflammation generally needs no treatment other than time. An abscess may need to be lanced and drained if it doesn’t break and drain on its own. If it’s an anaphylactic reaction, the animal could collapse and die and you don’t have much time, but you might be able to successfully reverse it if you have the proper antidote at hand when working cattle.

“When I’m doing a lot of vaccinations, I like to have epinephrine available. This is a vasoconstrictor,” says Niehaus. “If there’s widespread dilation of all the blood vessels [resulting in acute drop in blood pressure], this drug can help constrict those vessels to help bring blood pressure back up, and also increase heart rate, which will help increase blood pressure. This will facilitate better blood supply to all body tissues.”

Steroids like dexamethasone, used in conjunction with epinephrine, can also be helpful. Antihistamine are beneficial with a mild reaction but not much help in an acute case of anaphylactic shock.

“Anaphylactic reactions can be quickly fatal,” says Nickel. “Those animals may drop in the chute, immediately after the injection. If it’s that rapid, there’s nothing you can do to save the animal. I always recommend having epinephrine at the chute. You hope you never have to use it, but if you need it, you need it right now. If you have to run to the house to get it, it’s often too late,” he says.

It’s a good idea to include this as part of your kit at the chute (along with your spare needles, pliers, transfer needles, etc.) every time you vaccinate, especially if you have a lot of cattle. Your chances of having one react adversely to vaccine is greater if you are vaccinating 1,000 head than if you only have 10 cows.

“The unfortunate thing about epinephrine is that it doesn’t have a long shelf life [18 to 24 months, depending on how long it’s been sitting at the warehouse or clinic before the rancher gets it]. Always check expiration date,” Nickel says.

Ranchers sometimes wonder whether they should go ahead and use it even if that bottle is a year or two past expiration date. “If that’s all you have, it’s not ideal, but probably better than not giving it. The epinephrine might become less effective, but would not be harmful,” he explains.  end mark

PHOTO: There is always some small risk for reactions when vaccinating cattle, such as inflammations in this red-hided cow, even if the injections are given properly. Photo by Heather Thomas.

Heather Smith Thomas is a freelance writer based in Idaho.

Abortion side effects

“With some vaccines there are certain inherent risks,” says Dr. Andrew Niehaus, professor of farm animal surgery at Ohio State University. “One that comes to mind is abortion when giving certain types of modified-live vaccines like IBR-BVD. These problems are rare, but we generally recommend not vaccinating pregnant animals with modified-live BVD vaccine because of this risk.

Many of the new products have a label for pregnant animals, but you must follow label instructions carefully,” he says. If these animals have not been previously vaccinated and have no immunity, they would be at risk for possible abortion.

“The company will only stand behind the product if label directions are followed explicitly. It will likely state that the product must have been used before in those same animals, such as when they were heifers, before they were pregnant – with annual vaccination thereafter, so they already have some immunity,” he says.


With BVD, we know one of the issues with this disease is that it can cause abortion. “With the modified-live vaccine, a naïve animal [that has never been vaccinated] could have a lot of the same symptoms as the actual disease. One of those symptoms could be abortion,” explains Niehaus.