EPM Vaccine Argument

When there is a new drug or vaccine going through the approval process with FDA or USDA, there are certain criteria that have to be met. We discuss this in-depth in our article that begins on page 37. The federal government also accepts input from the public when a regulated product is undergoing official scrutiny. This is a chance for individuals and professionals in the industry to raise concerns about a product that they feel could harm an animal, or to promote a product and raise federal awareness of an equine problem that needs immediate medical attention.

If concerns come from reliable, knowledgeable people who are acting in the best interest of the horse and the industry, then I applaud them for their actions. Many times products--and federal laws--are accepted just because a group or company wants to make a profit, and the industry just sits back and complains after the fact.

There are times when concerns are raised that cause delays in approval of a product, or even prevent the product from ever reaching the industry. Maybe that's good, and maybe that's not so good.

Case in point.

There are some knowledgeable people who believe that the equine protozoal myeloencephalitis (EPM) vaccine Fort Dodge has in the approval process with USDA is a good thing for the industry. There are some knowledgeable people who believe that the EPM vaccine Fort Dodge has in the approval process with USDA is not a good thing for the industry. Here is the gist of the argument.

First, opponents say no one has successfully reproduced EPM in a horse in a research setting. In other words, scientists can't re-create the disease in healthy horses to test whether a vaccine would be effective. While this is true, there are other vaccines on the market--specifically for Eastern, Western, and Venezuelean encephalitis--for which there is no currently available challenge model. Equine influenza was another one where vaccines were approved without challenge models (prior to Heska's research on the intranasal type).

Second, opponents say the vaccine will skew the ability of tests to diagnose seriologically positive horses. I'm not sure there is much debate there from any side, but there is a debate whether the current tests are accurate in diagnosing disease.

Third, opponents say the vaccine isn't safe. If safe is defined as not causing problems when injected in horses, then from the research and field trials that have been done with nearly 900 horses, the vaccine is as safe as anything else we poke in our horses' necks.

There are more, but for the sake of space, let me give a horse owner's view.

  • If you live in an area where 50% or more of the horses test positive for exposure to the protozoal parasite that causes EPM;

  • If you know that a small percentage of horses will become clinically ill with the disease after exposure;

  • If you happen to have horses on a farm that has had one or more clinical cases of EPM;

  • And if you know that most of these clinically ill horses will never recover to 100% of their previous athletic ability;

Then I believe it is up to you and your veterinarian to decide if you want to use a vaccine to try and prevent--or attenuate--the chance of your horse getting the disease in your particular situation.

There are certain risk factors to diseases, and treatments. Let's say that you are not in the demographics that would put you in a high-risk category for becoming exposed to HIV and developing AIDS. Does that mean that research should not be conducted into a vaccine, and that vaccines should not be approved for "emergency" use because there isn't a challenge study available? There aren't too many human vaccines that have perfectly healthy volunteers say, "Okay, give me the vaccine, expose me to the disease, and let's see if the vaccine works."

As with human research, the active ingredient in the equine vaccine has to be shown in lab tests to fight the particular "bad guy" in order to be approved.

So, if the vaccine doesn't cause disease; if the vaccine doesn't cause adverse reactions beyond those expected with any vaccine; if the vaccine--based on science--might help prevent a horse from developing the disease; then why is there a delay in getting this vaccine to the public?

Whether you are opposed to this type of vaccine, opposed to this particular vaccine, or think either of these views is too restrictive, then you need to let your voice be heard.

Write to the federal authorities and let them know what you think at USDA/APHIS/VS/NAPH, 4700 River Rd., Suite 43, Riverdale, MD 20737.

About the Author

Kimberly S. Brown

Kimberly S. Brown was the Publisher/Editor of The Horse: Your Guide To Equine Health Care from June 2008 to March 2010, and she served in various positions at Blood-Horse Publications since 1980.

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