Vaccines: The What, Where, and Why
An important aspect of spring wellness is vaccinations against common and preventative diseases. While vaccines do not 100% prevent disease, it gives the body a leg up in fighting a disease on its own. We strongly advise in the use of vaccines as its safe, helps decrease the severity of disease, helps decrease the spread of disease, and maintains the relationship between veterinarian and client.
How do vaccines work?
When disease in the form of a virus or bacteria enters the body, they attack and multiply. The multiplication of the virus or bacteria is what causes disease. Vaccines stimulate the body’s natural defenses to develop immunity against specific diseases, they do this by imitating an infection. This does not cause illness but causes the immune system to react.
White blood cells help fight off infection. There are three predominant types of cells that participate.
Macrophages: eat material in the body such as germs and dead cells, leave behind antigens that other immune cells can identify
B-lymphocytes: respond to antigens and make antibodies, antibodies communicate to other immune cells to attack disease causing germs
T-lymphocytes: stimulated by antigen and antibody complexes to attack and destroy cells that were affected by the invading germs
Why should you have a veterinarian administer vaccines?
Veterinarian-client-patient relationship: vaccine appointments are a great opportunity to develop a relationship with your veterinarian and maintain an active relationship. This allows your vet to approve prescriptions as needed and prioritize your emergencies.
Proper administration and handling: with proper administration and handling of the vaccines, there is rarely vaccine failure. Your veterinarian will also help you decide which vaccines are necessary for your particular animal and environment they are in.
Assurance from vaccine manufacturers: if your horse develops a reaction to the vaccine that your veterinarian has administered, the manufacturer has a stake at being involved in the resolution. If the manufacturer knows that a veterinarian has administered it properly and it was stored properly, the manufacture is most likely to cover the costs associated with treatment for the reaction. Manufacturers want to stand by their product and continue to improve it.
What are the different types of vaccines?
Live vaccines: Contains agents capable of replicating within the horse that have been altered to decrease the pathogenicity. These vaccines generally stimulate long lasting immunity with fewer doses but can be risky in horses with immunocompromise or immune modulating medications such as steroids.
Modified live vaccines: contains agents derived from the original pathogen, these agents are altered using a variety of methods to elicit an immune response without causing disease.
Toxoid vaccines: contains inactivated toxins from bacteria to stimulate immune response without causing illness.
Inactivated/killed vaccines: lack pathogenicity and cannot replicate or spread between hosts. Typically requires multiple doses or regular boosters. Efficacy of these vaccines are dependent on the adjuvants, or additives.
The diseases that pose the most significant threat that we vaccinate for include:
Core Vaccinations:
Eastern Equine Encephalitis: EEE is a mosquito born viral disease that can cause severe neurologic effects. This disease is spread to horses through mosquito bites. (inactivated/killed vaccine)
West Nile Virus: WNV is a mosquito born viral disease that is transmitted to horses and humans by birds and mosquitoes. This disease also can cause severe neurologic symptoms. This disease is not transmitted from horse to horse or horse to human. (inactivated/killed vaccine)
Tetanus: Tetanus is caused by an ubiquitous soil bacteria everywhere in the horse's environment. Most commonly this bacterium is spread through puncture wounds, trauma, post foaling umbilical contaminations, or even surgical contamination. Tetanus can lead to muscle stiffness, spastic paralysis, and in unvaccinated horses’ death. (Toxoid vaccine)
Rabies: Rabies is a FATAL neurologic disease that can occur in all mammals. Rabies is present in all states except Hawaii. We confirmed a case in the roaring fork valley 5 years ago in a mule who had been bitten by a bobcat some weeks before showing clinical signs. Other common reservoirs include bats, racoons, skunks, and foxes. This disease is spread from wild animals to horses often through bites to the face. (inactivated/killed vaccine)
Risk Based vaccinations:
Equine Herpes Virus: This is a highly contagious viral disease that is spread from horse to horse. There are many subtypes but EHV1 and EHV4 carry the most significant health risk. EHV1 causes respiratory illness and can cause potentially fatal neurologic disease. (inactivated/killed vaccine or modified-live vaccine)
Equine Influenza: This is a highly contagious viral disease that can cause coughing, sneezing, nasal discharge, and fever. This disease can be rapidly spread in areas of dense horse populations and travel. (inactivated/killed vaccine or modified-live vaccine)
Strangles (Streptococcus equi subsp equii): An intranasal vaccination that helps protect against a upper respiratory bacterial infection in younger horse populations and those at risk at large show barns. (modified-live vaccine)
Written by:
Justine Stalnaker, DVM
Alpine Equine Hospital, PC
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