There are many difficult decisions to be made when changing the brand or manufacturer of a vaccine line. Hopefully this article will clarify how to go about making the decision and avoiding any gaps or overlaps that could develop if the right combinations are not chosen. The real comparisons can be made when you know what specific diseases you need to vaccinate for in your herd, whether you use a modified live, killed or combined program and how efficacious you think your original program was. This will help you and your herd veterinarian determine where to come in with different products. This is assuming the previous vaccines were purchased, stored, handled, and administered properly in a timely manner to all necessary cattle in your herd.
If you do purchase your vaccination supplies from your herd health veterinarian and they are changing lines it could be for several reasons, only one of which might be the efficacy of the product. Other reasons are availability, cost, dosage formulation, number of doses per bottle and even service provided by the pharmaceutical company. I have known clinics changing trade names simply based on the route of administration. If two vaccines are equal and one is approved to be given subcutaneously that may be a more desirable route. It also supports Beef Quality Assurance or Verified Beef Production protocols. Sometimes newer products protect against a broader range of bacteria or viruses making them more desirable. Vaccines that provide greater protection in fewer shots may be more desirable, as well. More shots simply mean more labour and stress on the calves. The intranasal route eliminates the needle and may have quicker protection but may have a shorter duration. These are all decisions you and your veterinarian need to make.
Knowing which vaccines do what requires reading the fine print, and you will find most pharmaceutical companies have pretty good spread sheets indicating what their vaccines protect against. Pay close attention. Vaccines can be very close in protection yet one organism may be missing. This is where it best to consult with your veterinarian in case there are any differences in coverage.
Once one has determined that all the diseases are the same then there is the question of whether you can carry on boosting the same way you have in the past. Just because you have changed vaccines does not necessarily mean you need to start a vaccine program all over again. In fact, the opposite is the case. Vaccines in general stimulate the body to produce antibodies or protection against that specific disease. If you then come in with a different vaccine, as long as immunity is there and the diseases are the same in the new vaccine, it should booster the previous vaccine response. This is much the same principal as if a natural, say viral infection came through; it would essentially stimulate the immune system the same way.
You need to follow label directions and if the previous vaccination program has worked well and you trust the protection it is giving the herd, then boostering with a comparable product should work fine. My only caution is when killed vaccines were previously used that the boosters were given according to label recommendation. If they were, then modified live vaccines or different killed products can follow it up. My personal preference is to use modified live vaccines for their longer duration of immunity, but some vaccines, such as the footrot vaccine, only come as a killed product.
Starting over may be recommended when you purchase new stock with a sketchy vaccination history, or if they haven’t been revaccinated for a year, so its now two years between vaccinations. If you aren’t sure of the vaccination, such as when an animal escaped from the chute, or the dosage was not calculated or the automatic syringes were not working properly, all of these situations may justify starting over with the new product.
The bottom line is if you are changing vaccines and your previous one gave protection and all the antigens are the same, you should be protected by the new vaccine. If new protection is being added then it may need to be boostered, but these are all good questions to pose to your veterinarian so gaps are not created in the new vaccination program.
As we all know vaccination is now a commonplace practice, and it is far better to prevent disease than treat it. All good reasons to work with your veterinarian yearly to come up with the most up-to-date, comprehensive and most efficacious vaccination program necessary for your farm and management style. Pharmaceutical companies will continue to improve vaccines making them more efficacious, broad spectrum and less reactive, coupled with, in some cases, easier means of administration. The future looks promising for the use of vaccinations to improve the health of our cattle herds and reduce antimicrobial usage.
The new slogan for Animal Health Week this year (Sept. 30-Oct. 6) is Vaccines Save Lives. This really applies to all species including our pets and production animal species.
Roy Lewis is an Alberta-based veterinarian specializing in large-animal practice. He is also a part-time technical services vet for Merck Animal Health.