Vaccinations for the North Idaho Horse

Vaccination is one of the topics that can be terribly confusing to the horse owner.  I can remember in our Sr. year of veterinary school (ironically the first time we had covered vaccination protocols in our education) hearing the vaccine lecture on each of my rotations through Equine Medicine.  It was probably my third rotation through that I finally began to feel like I had a grip on developing a vaccination program.  So, if you have had horses for years and you are still confused, don’t feel bad!  Let’s go over it one more time, shall we?

Core Vaccines

There are several disease that are listed on the core vaccination list.  These vaccines are recommended by the American Association of Equine Practitioners (AAEP) for all horses in all ages and stages at least annually.  The core disease are Easter Encephalomyelitis, Western Encephalomyelitis, Tetanus, West Nile and Rabies. 

Every single one of those disease has a high mortality associated with it.  That means that if your horse gets any of the disease listed on that core vaccine list he is likely to die.  Luckily the vaccines for all of these disease have been shown to be very effective and very safe.  This makes the risk associated with these vaccines far less than the risk associated with the disease. 

The other thing of note with the diseases listed on the core vaccination list is that they all come to your horse.  Both of the Encephalomyelitis strains as well as West Nile are carried by biting insects.  So, your horse doesn’t have to go anywhere to be at risk for those diseases.  Tetanus is of course found in the soil in every horse pasture.  Rabies, though not as common in our area as it is in other parts of the country, is found in our population of bats.  Of the core vaccines, this is the one that is least commonly administered in our area.  My current recommendation is to do rabies every other year for horses that live in areas where bats frequent. 

Because we are vaccinating our horses for diseases carried by insects it makes the most sense to vaccinate them in the spring months in North Idaho.  We recommend vaccination with the core vaccines between March and May. 

Risk Associated Vaccines

We are blessed to live in the pristine Northwest where our list of risk associated vaccines is relatively short when compared with other parts of the country.  The vaccines we include on this list are Influenza, Rhinopneumonitis, and Strangles. All of these disease are associated with co-mingling with other horses where they can pass the diseases back and forth.  These diseases tend to be more serious in young horses, though flu and strangles can be very tough on an older horse as well.

How do you decide if your horse needs these vaccines?  First of all any horse under 4 should have an annual vaccination for flu/rhino to help establish adult immunity. Rhino is a disease of the respiratory tract causing cough, runny nose and fever.  Rhino is caused by a herpes virus that almost all horses will have been exposed to by the time they are adults.  We vaccinate the young horses to keep them from having active disease when exposure happens.  Because it is a herpes virus, once they have been exposed they will carry the virus for the rest of their lives.  As adults the virus may recrudesce or become active again, typically during times of stress, causing a transient fever and rarely more serious disease.  Influenza is rarely seen as a cause of disease in horses under a year of age.  It causes fever and upper respiratory signs similar to Rhino but may last longer and prolonged periods of fever can cause dehydration which is the most serious complication.  Both of these virus can lead to secondary invasion by bacteria causing deeper respiratory issues needing prolonged antibiotics. 

Strangles is a bacterial disease that is highly contagious and causes swelling of the lymph nodes at the angle of the jaw often resulting a grossly distended throatlatch, hence the common name.  This is again typically a disease of younger horses and tends to be found where lots of horses congregate such as show grounds, training barns and sale yards.  Younger horses going into training should receive a strangles vaccine.  Because Strangles is a bacterial infection the vaccine is a “dirty” vaccine.  This means that it has an increased risk for causing infection.  It should be administered carefully and not in conjunction with other vaccines when possible. 

In my practice I recommend these vaccines for young and adult horses that are actively competing, boarding, or spending time where other horses congregate.  If you are generally a trail rider that maybe rides with 3 or 4 other horses on the weekends your horse is unlikely to need these vaccines.

While the core vaccines are recommended just annually the risk based vaccines are recommended to be administered biannually or at the commencement of show season. If you choose to administer your own vaccines you may find that your options at the feed store are limited to either a tetanus, a 2-way (flu/rhino), or a 5-way (EEE/WEE/Tetanus/,flu,rhino).  Giving your backyard horse a 5-way that they may or may not need is okay but you are probably over vaccinating.  The more things that are contained in a vaccine, the higher the risk of an adverse vaccine reaction.  Generally we will recommend splitting those products up and often will give the flu and rhino intranasally which is associated with fewer reactions and has been shown to have improved length of effectiveness. 

Severe vaccine reactions are rare and in almost all cases the risk of the disease outweighs the risk of the disease itself.  A typical vaccine reaction includes soreness or swelling at the sight of the injection and transient fever.  Rarer are injections site reactions, allergic reactions ranging from diarrhea and colic signs to hives.  If your horse experiences a reaction to a vaccine we may temper his vaccine protocol in order to mitigate those reactions and sometimes will eliminate some of the diseases that are at a low risk for your particular horse. 

We are so lucky to live in a time where we have safe and effective vaccinations against these deadly diseases.  We can safely protect our horses from diseases that we have no means of treating.  While the expense of vaccine may seem like an additional burden on an already stretched budget it is a drop in the bucket compared to the cost of treating any of these disease.