Thimerosal is a mercury-based preservative which is nearly 50% mercury by weight. Thimerosal was first introduced in vaccines by Eli Lilly in the 1930s. Thimerosal is a very inflammatory neurotoxin and genetic mutator and Pittman Moore Animal Pharmaceutical Company warned against its safety “even in dog serum” to Eli Lilly Company in 1935. Pittman Moore found that over 50% of vaccinated dogs suffered inflammatory reactions to Thimerosal.
These safety issues were raised in Congressional testimony several times and the correspondence from Pittman Moore to Eli Lilly is a part of Congressional Hearings testimony on the dangers of mercury in vaccines. Despite this, Thimerosal is still used as a preservative in a staggering number of vaccinations for both humans and dogs.
Symptoms of Mercury Poisoning
People who are exposed to mercury at levels above limits set by federal agencies such as the FDA and the EPA run the risk of mercury poisoning. Symptoms of mercury poisoning include:
- Difficulty walking or speaking
- Attention deficit
- Brain, lung, or kidney damage
There has been concern that mercury poisoning in young children is a direct cause of autism and this link has also been shown in animal research. These concerns are based on the similarities between the symptoms of mercury poisoning and autism. As a result, there was speculation that the thimerosal in vaccines may be connected to autism; however, an Institutes of Medicine report failed to substantiate these claims. Nevertheless, the Public Health Service agencies, the American Academy of Pediatrics, and the vaccine manufacturers agreed that thimerosal should be eliminated from all pediatric vaccines, and the amount of thimerosal reduced in other vaccines.
Thimerosal (mercury) Free Vaccines
A few companies are making canine rabies vaccines that do not contain thimerosal. Merial makes a thimerosal-free rabies vaccine called IMRAB 3 TF (the 3 designates a 3-year vaccine, and TF stands for “thimerosal-free”). There is also a 1-year version, IMRAB 1 TF. Fort Dodge makes a thimerosal-free rabies vaccine called RABVAC 3 TF (while it is not listed on their website, we did confirm with them that it is still available). Thimerosal is used in other vaccine products, but we don’t know of any specifically thimerosal-free versions. If you are vaccinating your dog for rabies, make sure you see the label of the vaccine and that the vaccine is thimerosal free.