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Ask the Vet Column: There are so many different kinds of vaccines out there, How do I go about choosing the right ones for my herd?

By Dayna Locitzer, DVM

This is an important question for many reasons. It is complicated to answer, but it is critical to think about as we consider a multipronged approach to preventative medicine. So, NODPA readers, I’m glad you asked! First off, I’d like to say that this is a great topic to discuss with your veterinarian since they know your herd and can supply you with the vaccines that are available for use. Veterinary suppliers are experiencing a lot of shortages, so unfortunately this question will depend on what is in stock. But for now, I will go over the basics to help you start to think about your vaccine program.

The first question to answer is: Do you have an open or closed herd? A closed herd is when no animals have been introduced to your farm in a number of years. If you buy a heifer from a neighbor or bring in a bull or send your heifers away to a heifer grower or take your animal to the fair and back, then you do not have a closed herd. When cows have the ability to interact with cows from other farms, they have the ability to pick up novel infectious diseases from those animals. This comes in the form of “shipping fever,” or bovine respiratory disease complex. When you have an open herd, it is important that you are well vaccinated for pneumonia and abortion causing diseases.

What is “well vaccinated”? Basically, it means that you are providing your cows with a vaccine that will create a strong and lasting immune response in the face of disease. This is best accomplished with a modified live vaccine (MLV). A MLV contains active, replicating virus that has been altered to not cause disease in the host but, rather, to introduce the host to elements of the virus. When you are using a whole intact (but modified) virus, it creates more targets for the immune system to study and prepare its response. This translates to a more robust and lasting immunity.

But it comes with some downsides. MLV has live virus and sometimes can revert to virulence and cause diseases similar to what you are trying to prevent. Also, the creation of this immunity is taxing on the animal and can cause a vaccine reaction resulting in animals that are a little “off” for a short period of time. When using an MLV, it is important to plan how many doses you need because when you mix up a bottle you have to use the whole contents right away. This can be hard when you only have a small number of animals to vaccinate.

The alternative is a killed vaccine which has chemically altered virus that is no longer able to replicate when injected as a vaccine. While they don’t come with the risks of live virus, they also don’t provide as long lasting effective immunity, and they always need to be “boostered” after first administration.

Killed vaccines are similar to bacterins, which are vaccines for diseases caused by bacteria. Bacterins also contain chemically altered non-viable pathogens, in this case bacteria. They can have variable efficacy depending on the pathogen. For example, bacterins for E.coli causing diseases do not provide long term immunity and only decrease the severity of disease. This is in contrast to clostridial bacterins (for tetanus, black leg, redwater, etc), which can actually prevent disease and provide long term immunity.

There is another type of vaccine folks might be familiar with: mRNA vaccines. Many of the vaccines preventing severe disease and illness from COVID-19 were classified as mRNA vaccines. This type of vaccine has a strand of directions called mRNA that instructs the immune system cells to build a harmless piece of the offending virus. In the case of COVID-19, that piece is a spike protein. The immune system then learns to recognize the pathogen and prepares to mount an immune response if and when it is confronted with the actual disease. While I don’t want to get into a discussion about the controversy around this type of vaccine, I will say that there are currently no mRNA vaccines that are approved for use in cattle. This means that none of the vaccines recommended to you by your veterinarian are mRNA vaccines. It is also important to remember that all vaccines have a 21-day meat withhold, preventing any recently vaccinated animal from entering the food system.

A tenant of successful organic dairy farming is taking a multipronged approach, whether it’s for soil health, pasture management, or preventative medicine. Providing good preventative care includes excellent animal welfare, appropriate nutrition, protocol development and planning for disease. Vaccines are a preventative medicine tool that can help prepare for the real possibility of disease on farm. Organic farming is limited when confronted with diseases common in dairy cows. It is valuable to utilize all strategies to prevent these diseases. Vaccines are safe to use, and all cattle vaccines available are approved for use in organic. I encourage you to talk with your veterinarian to better understand what vaccines would be best suited for your farm’s needs.