The theory of an intranasal vaccine for Strangles is that the site of entry and infection with Strangles is via the tonsils located in the nose and mouth. If we stimulate immunity at these sites by introducing a vaccine directly to those tonsils, we can limit the propagation of the bacteria at its site of entry. The Strangles vaccine most commonly used is a modified live bacterial vaccine, which is unable to replicate but mimics the immunity stimulated by a natural infection. However, its efficacy is dependent on an adequate amount of the vaccine reaching the tonsils deep in the head, so it must be administered via the nasal passageways.
Most horse people have heard of Strangles, and many have had the unfortunate experience of dealing with an outbreak. The disease, sometimes referred to as “distemper,” is not new—it was first reported in 1251. The disease is highly contagious. Young animals (weanlings, yearlings, and other young stock) are particularly susceptible, however any age of horse can be affected.