So my last post was about strangles, and I decided to look into the finer points of the argument over whether or not the strangles vaccine actually works. Some people say that it may even increase the chance of the vaccinated horse getting strangles.
On a personal note, I have an acquaintance whose horse had strangles a couple of years ago after the horse had been vaccinated not long before. Somehow, the horse was re-vaccinated for strangles in the fall after recovering from the infection, and got strangles again! It seems that either the horse never fully recovered from the infection or the vaccination sort of re-activated the infection. I'm not sure whether the vaccine was intranasal or injectable, but it seemed to have caused a lot of painful and expensive trouble.
Honestly, vaccination is really your best protection against strangles. Other than completely isolating your horse or wrapping it in a plastic bubble, vaccination is the best choice. Some old-fashioned horsemen and horsewomen that I've talked to say that they don't believe in the strangles vaccine because usually only their younger horses are affected and are easily treated, or they believe that a modified live vaccine could potentially increase the chances of their horses getting strangles.
I did some research on the American Association of Equine Practitioners website (http://www.aaep.org/strangles.htm?page_name=strangles). Under the killed vaccines section, they say that it can be associated with injection site reactions.
In my opinion, the best thing to do is talk to your vet about the strangles vaccine, and maybe get a second opinion from another vet in your area. Determine the need for your horse to get the vaccine based on their health and their environment, and work out a strangles vaccination schedule with your vet.