It can be a challenging decision as to whether or not to vaccinate your horses and, if you are vaccinating, which of the myriad of vaccines you should be doing.
Every year there seems to be some new, nasty disease out there threatening your horse, so this is a potentially life-saving decision you are making.
The first step in making the decision is determining what the risks are in your area or the areas where you will be taking your horse. Your local veterinarian is a great resource to help you determine what diseases your horse could potentially be exposed to. Keep in mind that if you are taking your horse to competitions where other horses will be coming in from other areas, you need to consider their areas as well. Horses can be carriers of disease, but not exhibit any symptoms of the disease, thus exposing your horse without you even being aware of it.
It is important to note that not all vaccines are created equal — now we use both “dead” or “killed” versions of the virus or bacteria that causes the disease, as well as a wide range of other forms including modified live (live attenuated) vaccines, sub-unit vaccines, DNA vaccines (still experimental, not widely available), intranasal vaccines and adjuvants (substances added to vaccines to improve the immune response). If you want more information on the specifics of these vaccines, they are all described in detail in the latest issue of Horse & Rider in an article entitled ‘Hit ‘Em with Your Best Shot’ by Barb Crabbe, DVM.
Basically, a vaccine is designed to cause the immune system of the horse to respond to the vaccine by stimulating the production of antibodies against that specific disease. These antibodies are then ready to protect the horse by preventing the invading disease from infecting your horse. The response by the immune system can vary in intensity depending on the nature of the vaccine. Additives to the vaccine (adjuvants) can enhance the response and increase the effectiveness of the vaccine.
They can have the negative effect of increasing the chance of side effects and unfortunately, my horses found this out the hard way. I recently had all my horses vaccinated with the new six-way vaccine (Encephalomyelitis-Rhinopneumonitis-Influenza-West Nile virus (east and west, killed virus) Tetanus Toxoid). All of my horses had a bad reaction at the injection site.
Fortunately, the vet had injected in the lower chest area, otherwise it could have been nasty.
The reaction was a large swelling (grapefruit sized on the full size horses, small orange size on the minis) and three of the horses were extremely sore and were uncomfortable walking. The swelling did subside over a couple of days (hot compresses helped) and all ended well.
Apparently, different manufacturers use different adjuvants, so we won’t be using that particular vaccine from that manufacturer again. One never knows what kind of reaction (if any) you are going to get in your horses, so it is wise to plan the administration of vaccines at a time when you won’t be using the horses for a couple of days.
There is constant research improving the safeness and effectiveness of vaccines. For example, there are several different vaccines available for West Nile virus — an original killed vaccine and two newer ones using different technology resulting in two different recombinant vaccines (one with an adjuvant and one without). The decision on which one to use is based on where your horse is and what the risk of exposure is.
The key in all of this is to know what diseases your horses could potentially be exposed to, understand how these vaccines work and make an informed decision as to what you want to do to protect your horses effectively.
