Vaccination reactions |

Vaccination reactions

The neck is the preferred location for injections, but if the neck is covered with mud or manure you may need to select a cleaner site — which is often behind the shoulder.
Photo by Heather Smith Thomas

Occasionally cattle react to vaccinations. A reaction can be mild and local (swelling at the injection site after vaccination) or serious and fatal — if the animal goes into anaphylactic shock.

Vaccines contain antigens that are “foreign” to the animal’s body. The goal is for the body to recognize these as foreign and to develop immunity to combat these antigens in the future. Vaccination enables the animal to create an immune response. On rare occasions, however, the vaccinated animal may develop an acute allergic reaction to the foreign substance. Reactions can range in severity from hives/itching to systemic shock — with fluid in the lungs and sudden death.

Dorothy Erickson, DVM, manager of veterinary services for cattle, Zoetis, said there are several factors that can contribute to a vaccine reaction. Some of these can be prevented or controlled and some cannot.

“Things like how we handle and administer a product, stressful events that occur at the same time we are vaccinating (such as handling of the animal) and weather (we should not vaccinate during inclement weather, which can be another stress) can make a difference. Other things, like genetic predisposition are things we generally can’t control. Certain individuals are more predisposed to reactions, like people with hypersensitivity and allergies,” she said. This is why we sometimes see a cluster of reactions within a certain herd or in a particular genetic line of animals.

Janice Berg, DVM, director, veterinary affairs for Merck Animal Health, said the clostridial vaccines are the ones that most commonly produce local injection site reactions with swelling. These local reactions tend to resolve with time and the animal doesn’t need treatment. Occasionally a large injection-site reaction can make the neck sore for a few days if the injection was in the neck.

“If the animal is very sensitive to the vaccine, it can be a large swelling, and might be a concern, especially if the animal is reluctant to move, and lame for several days (if the swelling is near the shoulder and pain hinders shoulder movement when the animal walks). Even if a person is not using the neck site and injects subcutaneously behind the shoulder, this can impair the shoulder’s range of motion as well,” she said.


There are degrees of reaction, from mild to severe — everything from just a temporary local swelling at the site of injection to a full-body reaction, with the animal going into shock and dying. “Anaphylaxis is the most severe type of reaction and can be acute and life-threatening. Generally this would occur within about 10 to 20 minutes after administration of the vaccine,” Erickson said.

Sometimes a serious reaction happens so quickly there isn’t time to administer treatment and/or the animal may not respond to treatment. “Signs of anaphylaxis include rapid breathing, muscle tremors, swelling around the face (such as puffy eyelids), or excessive salivation (drooling). The animal might seem to be uncomfortable. If the reaction is severe and progresses, the animal will collapse, unable to get up; it will go into shock and die, unless treatment is administered immediately,” Erikson said.

“There are some things we can do to help reduce risk for reactions, and these include proper vaccine storage, handling and administration. How we store vaccine (at proper temperature), mix it up (if it’s a modified-live vaccine) and handle it can make a difference,” she said.

“Always use a clean needle to draw vaccine out of the bottle or mix it, and change needles often when giving injections. This is important for cleanliness, and to avoid tissue damage. Once a needle starts to get dull, it is more likely to cause damage. Select appropriate needle size for the injection and give the product according to label. Some are labeled for subcutaneous use and others for intramuscular, and some give you the option for route of administration,” Erickson said.

Another important factor is how many vaccines you are giving at the same time, or concurrently with other products. “Certain products are more likely than others to cause reactions and we want to make sure we don’t give too many of those at one time. Work with your veterinarian on vaccination schedules and protocols, and let him/her know what else you will be giving at the same time, such as treatment for parasites, vitamin or mineral injections, etc.” Some products may interact with or negatively impact others and you might not want to give them all at the same time.

“Contamination of vaccine during vaccination (or administration of any product) can lead to abscesses at the injection site. These swellings look very similar to swellings due to vaccine reactions but are actually due to infection,” she said. Always make sure you are not injecting through a dirty hide.

“If the animals are excessively dirty or weather is bad and cattle are wet, it might be better to delay vaccination until they are cleaner. That may not be possible, so at least try to find the cleanest spot,” she said.

Berg said the neck is the preferred location for injections, but if the neck is covered with mud or manure you may need to select a cleaner site —which is often behind the shoulder. “Just administer the injection far enough away from the shoulder (either in front or in back of it) that it won’t interfere with movement if an injection-site swelling occurs,” Berg said.

It is also important to reduce stress while handling the animals. “The less stress, the less likely you might see reactions, in some situations,” Erickson said. “Weather can be a stress, so try to avoid vaccinating cattle in very hot weather. If it’s going to be a hot day, try to vaccinate in the morning, or delay vaccination until a cooler day, to ensure you are not increasing risk for reactions due to the stress of hot weather while cattle are experiencing the multiple stresses of handling and vaccination,” she said.


Some reactions can’t be predicted or prevented, so the important thing is being prepared. “It’s wise to always have epinephrine on hand, and corticosteroids such as dexamethasone to treat an animal that has an anaphylactic reaction,” Berg said. “It is crucial to treat these as soon as possible, especially if respiratory distress becomes severe, because these animals can quickly die.”

After the cattle have been vaccinated, monitor them closely for at least one to two hours and watch for any signs of reactions. “Most fatal reactions occur within the first few minutes, but a reaction within the first hour can be life-threatening if the animal is not treated. You’d see the animal acting abnormally, having difficulty breathing, and possibly drooling,” Berg said.

“The lungs are the organ most affected, in cattle, so there is usually some respiratory distress. Fluid starts to build up in the lungs and the animal basically drowns. The animal may become agitated or anxious because it can’t breathe very well, and there may be muscle tremors and shaking. The animal becomes quite distressed and collapses. When you see any of these signs, it is imperative to treat immediately,” Berg said.

Usually if you find and treat an animal in time, you can reverse the reaction with an injection of epinephrine. “Reactions in general are uncommon, and anaphylaxis is even less common, but there is always some risk with any pharmaceutical product, so it is important to be prepared,” Erickson said.

“The primary treatment will be epinephrine, and it may need to be repeated, depending on the animal’s response. Don’t just give one shot and walk away, expecting the animal to be fine. It’s important to monitor that animal and see if one injection was sufficient to reverse the reaction. In some cases a single dose will do it, and the animal will recover just fine, but in other cases it will need to be repeated,” Erickson said.

“If the animal seems to be improving within 15 to 30 minutes, it will probably recover, but if it is not improving (or declining), repeat the injection after 15 to 20 minutes. Watching their breathing will be the most important clue because the thing that ultimately kills them when they go into shock will be fluid in the lungs — and subsequent suffocation. I recommend monitoring cattle for at least an hour after the injection of epinephrine, to make sure they are going to recover,” she said.

Other things your veterinarian may recommend for treatment include steroids and/or antihistamines to decrease swelling in the airways and lungs that hinder breathing. It is important to have some of these medications on hand (epinephrine, antihistamine, dexamethasone), to be prepared for serious reactions.

In most cases, your bottle of epinephrine will expire before you use it (and you may need to replace it periodically), but it’s still worthwhile to keep some on hand in case you ever need it. Occasionally check the expiration date and replace it when it gets out of date. “You might not need it for several years, but if you do, you want it to be effective. Replacing it will be very inexpensive compared with the loss of an animal,” Berg said.

Keep epinephrine in your chute-side kit when vaccinating cattle (along with your spare needles, transfer needles, pliers for changing needles, etc.) because if you have to run back to the house to get the bottle, this may be too late to save the animal. It’s best to have it on hand when processing cattle, and discuss a treatment plan with your vet ahead of time — and know what the proper dose would be, and how to administer it.

If you have this all straight in your mind, you won’t be wasting precious time trying to read the fine print on the label while the animal is dying. “I recommended putting a piece of tape on the bottle and writing the dose on it in big letters, so it will be easily visible,” Erickson said. “It’s easy to forget, especially if you don’t have to use it very often.” And if you’ve never had a severe reaction in the past, and never had to use this product, it will be helpful to have an easy-to-read dose label if you ever need to grab it in an emergency.

Sometimes an animal dies so quickly (collapsing immediately after the injection) that there’s no time to give epinephrine. “What we suspect in those cases is that the injection may have been given near or into a small artery. In those situations it may not be anaphylaxis; those animals might not respond to epinephrine,” Erickson said.

If a certain animal has a severe reaction and recovers, be cautious about giving that same vaccine again the next season. These reactions tend to be worse the next time, and the animal may die. “That animal is already sensitized to whatever protein antigen is in that vaccine, and there’s risk for this to happen again,” Berg said.

If you are giving multiple vaccines to an animal at the same time, and getting injection-site swellings, make note of which vaccine you give where. For instance, if you always give the clostridial vaccines on the left side of the neck and the IBR-BVD injections on the right, you’d know which injection caused the local reaction. ❖

— Smith Thomas is a cattle rancher, horseman, freelance writer and book author, ranching with her husband near Salmon, Idaho. She can be reached at


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