Vaccinations, Yes!


This afternoon, a client asked me “ What are your thoughts on vaccination?” Without blinking I said “ Yes, do it!” She stared at me for a moment, and said “ well, but, vaccinations have lots of down sides..” I said to her, and say to you “ No, they don’t. Vaccines are one of the most meaningful medical advancements of all time. The only reason we demonize them is because we live in a country and an age where most of the serious diseases we vaccinate for are completely or mostly eradicated. Ask someone in a country where childhood polio is still a serious disease threat about the “down sides” of vaccines.” See what answer you get.


Now, before they have even gotten this far in the post, some of you will be saying “ Well of course she promotes vaccines. Vets make tons of money off vaccines.” Let’s clear something up right now. I don’t care WHO you pay to do vaccines, or if you do them yourself. I do not make much money off of them, especially when you consider the cost of carrying inventory for the spring vaccine season before I am actually paid for them. I DO sincerely HATE watching animals die of diseases that are easy to prevent. End of story. You can order your vaccines from an online retailer and give them yourself if you want( though I wish you would tell me so I can give you some epinephrine to keep on hand and tell you how to use it). I don’t care. I just want them vaccinated so that I don’t have to watch horses die from preventable diseases.


The term “vaccinosis” has been thrown around in blog posts , magazine articles, and websites to indicate disease caused by “over-vaccination”. “Vaccinosis” is a term that was invented by a natural health practitioner over a hundred years ago. In the intervening time, not one study has been able to prove that vaccination causes disease of any kind. On the contrary, the advancement of vaccine science has made both animals and humans healthier. Many times you will hear that the vaccines overload the immune system, or “wear it out”. However, this effect can not be shown scientifically in anyway. There is no actual proven connection between vaccines and any type of autoimmune or other disease. In human children the vaccinations they get are estimated to use no more than about .01% of their immune system. Even if horses used .01% of their immune system every year for yearly vaccination, considering 30 years is a long life for a horse, that would mean only 3% of their immune system has ever been used or taxed in any way. Given this , it seem impossible that we are “wearing out” their immune systems . It is true that vaccination will sometimes cause swelling, low-grade fever, or in rare cases anaphylaxis. However problems such as malaise and muscle swelling are short lived and not life-threatening. Anaphylaxis, while life threatening, is rare and can be combated by the timely administration of epinephrine. Remember that those who try to convince you vaccines are bad for your horse are often trying to sell your something too.


In contrast to the small risk posed by vaccines, let us consider some of the diseases we vaccinate for in horses. I have been unfortunate enough to see horses die of West Nile virus, Eastern Encephalitis, tetanus, and Potomac Horse Fever. Having previously worked in Amish country, where vaccination is rare, I got to see up close that not vaccinating puts horses at risk of disease. These are horrible diseases and the horse that dies from them suffers tremendously.


Tetanus is up to 80% fatal in horses, who are among the most susceptible of domestic animals to disease. The disease begins with fever and malaise, progressing to muscle spasms, and finally severe muscle tetany so that the animals muscles are stiff and unmovable. The animal may die of suffocation as they become unable to breathe due to muscle tetany. It is a horrible way to die. Treatment is extremely expensive and often unsuccessful by the time symptoms are obvious. The tetanus vaccine is extremely effective and offers nearly 100% protection from the disease.


The encephalitis viruses ( Eastern, Western and Venezuelan Encephalitis) vary in fatality rates. Western and Venezuelan Encephalitis are fatal in 40-70% of cases, while Eastern Encephalitis ( the most common in Michigan) has a 90% fatality rate. The disease causes swelling of the brain and a colloquial term for it is “sleeping sickness”. Horses develop fevers. They will then show various signs consistent with the brain swelling. This can include blindness, head tile, inability to walk or stand, inability to eat, seizures, or other issues. It is very difficult and expensive to treat in the rare cases where the horse survives as intensive care must be directed at keeping food and water in the horse who can not eat or drink on its own, protecting them from muscle damage do to not being able to stand, and protecting them from head trauma caused by seizures or other abnormal behavior. Again the vaccines for the these diseases are very effective, preventing disease in almost all cases.


West Nile virus is also an encephalitis. The fatality rate in affected horses is up to 70%. Symptoms are very similar to those of Eastern, western, and Venezuelan encephalitis. Again, we have effective vaccines for it.


Potomac Horse Fever is a disease that causes fever, diarrhea and laminitis in affected horses. The death rate can be up to 30% in affected horses. The vaccine for Potomac Horse Fever is not as effective as some others due to the nature of the organism that causes it. It will not always prevent disease. However, many practitioners, myself included, believe that vaccinated horses have shorter, milder courses of the disease. In 13 year of practice I have never seen a horse who was vaccinated for Potomac Horse Fever die from it, whereas I have seen at least 30 unvaccinated horses who died from Potomac Horse Fever.


This does not include all the diseases we vaccinate for , but it includes some of the worst. Watching horses die from these diseases is heart wrenching, not the least of all because they are preventable. Always, the animals suffer greatly before they die.


Some horse people view “nosodes” or homeopathic vaccines as alternatives to traditional vaccines. Nosodes are created by diluting pus, blood, mucous, or feces from a sick animal in order to create a tincture that supposedly will prevent the disease. First for those who view this as a better alternative than the chemicals in vaccines, let me repeat that :pus, blood, mucous, or feces from a sick animal. While in various places on the internet you will see statements such as “nosodes are as effective or even more effective than traditional vaccines”, this is blatantly false. For a vaccine to be approved the manufacturer must perform what is called a “challenge study”. Horses are vaccinated with the vaccine, and then exposed to the disease the vaccine is supposed to prevent. To be approved the vaccine must be shown to be effective in preventing the disease. There have been few challenge studies with nosodes . However, a notable one involved parvovirus in dogs. The traditionally vaccinated puppies were challenged with parvovirus. 9 out of 10 puppies who were vaccinated survived. The puppies vaccinated with a nosode protocol fared very differently . Only 10% of those puppies survived. 90% of the nosode vaccinated puppies died of parvovirus. In addition, studies done to evaluate antibody production after nosode administration noted that nosodes did NOT result in the body creating antibodies to disease. Nosodes at this point have been proven to be ineffective in preventing disease.


Another issue is people bring up repeatedly in vaccination frequency. Since we vaccinate school children and then stop vaccinating once they are older. We get tetanus vaccinations only every 7 years. First of all, susceptibility and the amount of protection offered by vaccines differ in between species. In horses, there have been documented cases of tetanus in horses who were vaccinated more than 1 year but less than 3 years previously. So obviously the 7 year rule of tetanus does not apply to horses because as a species horses are more susceptible than humans. This is only one example, but on the whole, the horse’s immune system is somewhat fragile. One trailer ride can significantly alter their ability to fight off a disease. These species differences mean we can not extrapolate human experience to horses.


In humans and dogs we sometimes pull what are called titers, which is a test that will measure the amount of antibodies you have to a particular disease. The problem with titers in horses is we have no idea what antibody level the horse needs to be protected against a disease. So at best we would be guessing at whether the horse needs to be revaccinated or not. In addition titers end up being many times more expensive than vaccinations. So while titers are a good idea and could become useful as more research in done on what titers will protect a horse from contracting various diseases, right now they are a waste of money.


There is no single “right” vaccine schedule for a horse. The correct vaccine schedule depends on how much risk the horse has of being exposed to various diseases, how old they are, what their prior vaccination history is, how much they travel, and other variables. Horses who have systemic problems such as Cushing’s disease or a history of bad reactions to vaccines may need a program tailored to them.


However, in the end, vaccines still provide the single greatest “bang for your buck” in terms of disease prevention. They are the safest and most reliable way to prevent the diseases we can vaccinate for. Vaccines have revolutionized the health of humans and animals across the globe. So my thoughts on vaccination are simple. Yes. Vaccinate.

About Whole Horse Vet Services

I'm a mobile equine vet with a special interest in lameness roaming the countryside helping out horses and their people.

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