It is the fall season and many people are inquiring about what vaccinations they should give their horse. Equine Rhino, Equine Influenza, Potomac Horse Fever, and Rabies are the common ones asked for in this area of the US. However are they worth it? Do you actually know what they do and how they protect? Did you know that many times they do not protect at all like you think they should?

Equine Rhinopneumonitis, one of my favorite diseases to bash the vaccine. Why bash the vaccine? Well to put it bluntly and simply, because it doesn’t work in protecting your horse. This is a herpes virus and like the herpes viruses in humans it can infect the animal for life. The virus remains dormant and the horse will not show signs of infection, this is called latency. However during periods of stress, such as show season, out breaks can occur. The vaccine for rhino does not appear to be able to prevent these outbreaks and is questionable as to whether it even helps stem the signs and symptoms. The disease causes respiratory signs, abortions and infrequently a paralyzing neurologic disease with similar signs as the infamous Equine Protozoal Myelitis (EPM). The neurologic form has been in the news for the past couple of years because there appears to be a very virulent strain causing the neuroplogic form that has closed racetracks in Maryland and has had a very large impact on the horse industry where ever it has been found. The vaccines for rhino do not produce antibodies in all horses, in fact, most vaccines produce antibodies in only 80% of horses. In the horses that it does produce antibodies, they last for a very short time (2 to 3 months); and even though it may produce antibodies this doesn’t mean the horse is protected from acquiring the disease. Currently the studies show that the vaccines are able to effectively reduce the symptoms of the respiratory form of the disease in about 50% of the horses. One last bit of bad news is that none of the vaccines out there are able to protect against the neurologic form of the virus.

So now you are asking, “Why am I vaccinating for this disease it appears that the vaccine doesn’t work?” Short of saying, “I don’t know.” it does appear that multiple vaccination (every 3 months) in high-risk horses, such as show horses, reduces the severity of the disease. In pregnant mares it appears to prevent abortion storms meaning multiple abortions on the same breeding farm; however the disease can and will still occur in individuals, because some horses do not respond at all to the vaccine. So if you are willing to give the vaccine every three months…oh wait there is a problem with doing this as well…. the immune system has a limited capacity for responding to vaccine. If you give it too many vaccines at the same time or space them too closely, you dilute the immune response to each vaccine. So giving multiple vaccines every two to three months over a long period of time will reduce the effectiveness of the vaccine which has a poor effectiveness to begin with. Not to mention that in dogs and cats it has been discovered that multiple vaccinations causes (let me repeat) causes immune system failure such as allergies, cancers and autoimmune diseases. Check out – Is Your Vet overvaccinating your dog? for more information. The horse is a different animal but there is anecdotal evidence in horses with allergies that reducing the number of vaccines up to totally eliminating them reduces the severity of their allergies to the point where they are unnoticable.

So lets bring this back to fall vaccinations…the last time your horse may have received a rhino shot was in the spring. The vaccine, if it produces antibodies in your horse, lasts 2 to 3 months, it is what now 6 months or 9 months later? How effective has that vaccine been in protecting your horse? So why are you wasting your money? So No – Equine Rhino Vaccination is not worth it.