Fall vaccinations are a vital part of a successful health program for beef herds. This includes preconditioning programs for feeder calf sales as well as maintaining an effective health status in the cow herd. Sometimes you hear a producer remark about cattle or calves that get sick anyway following being vaccinated. The usual answer is "that vaccine was no good." There is a lot more to vaccine failure than just the stuff that comes out of the bottle.
The failure of a vaccination program to prevent disease can be outlined in three parts: the animal, the people, and the vaccine. As described by Thayer (2011) there are "broken animals." Despite administration of a good vaccine, the cattle will still get sick. The causes are numerous, but are usually confined to the environment for the animal, the parasite and other health status, stress, and the nutrition status. Healthy cattle, primarily calves that are under some form of stress from the environment will not respond properly to vaccines. This includes extremes in weather, dehydration, or other environmental factors. Stress from transportation, weaning, castration, comingling, or simply handling can reduce the ability of the animal to develop the desired immunity to a disease from the vaccine because these activities are additive sources of stress. When weaning calves this fall, either vaccinate ahead of weaning or wait several days until the stress has subsided. Combine as few other management activities as possible with vaccinations. When receiving cattle, the 24-hour rest period before handling new cattle will allow the transportation stress to subside and the cattle to rehydrate. Cattle that are already sick will not respond well to vaccines. If there is some indicator the cattle are sick, first use a treatment for the disease to correct the problem. This feature also includes heavy parasite loads. Cattle obviously in a malnourished state will not respond well to vaccines. The immune status of young cattle can also be decreased from maternal antibodies for very young calves. Generally calves under 3 months of age are still under the protection of the colostrum antibodies received at birth. The immune system in these animals either may not be fully developed or may be protected from the vaccine challenge and not respond. Cattle beyond 90 days from their last vaccination begin to decline in the level of their protection.
Vaccines also fail because people do not use them correctly. Understanding the causes of stress already outlined should be considered when handling the cattle and planning vaccinations. The protocol for the use of a vaccine is on the label of the product and should be followed exactly. Vaccines that are not mixed correctly, usually modified live vaccines, will not work under the best of conditions. Mix only the amount of vaccine you are going to use within the next hour, keep a cold cooler at the chute side to hold the mixed product, do not shake the mixed product harshly and use a transfer needle for mixing. Don't ever wipe the top of a modified live vaccine bottle with an alcohol swab. Never mix different vaccines in the same syringe. Storage of any vaccines in the pickup is another source of failure. Vaccines may become overheated or freeze, or be exposed to sunlight. Mix, handle, and store vaccines according to the label. A good general rule is to use a new needle for each animal. Needles used on multiple animals can distribute diseases through the herd. This includes but is not limited to bovine leucosis virus for which there is no vaccine. Sometimes the vaccine just does not get in the animal properly. The desired route of administration is outlined on the label with subcutaneous being the preferred method. Products requiring intramuscular(IM) administration can fail from leakage at the vaccination site. Also by not injecting the product deep enough into the muscle to allow vascular contact generally resulting from using the wrong size needle. In most cases an 18 gauge needle 1 ½ inches long should be used for IM vaccinations. Needles that are too short do not deposit the product correctly and those too big cause injuries and bleeding that will disrupt uptake of the vaccine.
The main reason the vaccine itself fails is because it is the wrong product for the disease. Most of the time, however, vaccines contain most of the major serotypes for the disease they are intended to control. If there is a disease issue in the herd, use the best vaccine for that disease by making sure you know from tests what disease is present. A vaccine can fail when the disease challenge is greater than the level of immunity, and this occurs most often when proper boosters were not given or the stress challenge occurs shortly following administration and the immunity has not developed. Again, the label will describe the timing and the need for boosters. Some boosters are recommended for multiple times each year depending on your particular level of exposure. Timing of vaccination is critical in some cases. For example, pinkeye and scours vaccines must be administered ahead of a challenge. Modified live vaccines for cows should be given after calving and before the breeding season starts to prevent abortions. Vaccinations and boosters will be needed prior to transportation, weaning, and other high-stress activities for feeder cattle if the stress is going to occur 90 days following the last vaccination.
No vaccination program will prevent 100% of disease challenges, but the odds can be improved by understanding the status of the cattle, using good vaccination management technique, and using the right vaccines at the right time.
- Mass, J. and J. M. Harper. 2011. Quality Assurance and Vaccines. University of California-Davis.
- Rice, D., E. D. Erickson, and D. Grotelueschen. 1986. Causes of Vaccination-Immunization Failures in Livestock. University of Nebraska, Lincoln.
- Thayer, T. 2011. When Vaccines Fail. Dairy Today Healthline, August 1, 2011.
Prepared by Dr. John Comerford, retired Penn State professor