Total mercury content in canine hair before and after administration of vaccines containing thiomersal.

Objectives: Thiomersal is ethylmercury containing compound. It has been used as a preservative in vaccines since the 1930s because it is very effective in preventing bacterial contamination. Ethylmercury penetrates into growing hair in a similar manner as methylmercury.
Design: A total of 48 hair samples were collected from vaccinated dogs. Each sample was accompanied with a questionnaire including data on age, gender, vaccinations. Total mercury content in hair, granules and vaccines was determined by the direct method of cold vapours using an AMA 254 (advance mercury analyser; Altec Ltd., Czech Republic).
Results: At first we performed two pre-experiments. In first pre-experiment, the highest value of total mercury content was 0.732 mg.kg-1. The content of total mercury ranged from 0.022 to 0.092 mg.kg-1 in the second pre-experiment. The results were not statistically significant in the pre-experiments. In the main experiment the lowest concentration of total mercury in dog's hair was 0.002 mg.kg-1 and the highest value was 0.560 mg.kg-1. The median value of total mercury ranged from 0.023 to 0.033 mg.kg-1. The results were not statistically significant in the main experiment. Total mercury content in vaccines corresponded with the declared quantity. Rather, results showed mercury content to be correlated with the consumption of feed containing fish.
Conclusions: Thiomersal preservative, contained in vaccine, does not increase content of total mercury in canine hair. Our results have shown that content of mercury in hair depends on fish consumption (fish granules, fish treats and fresh fish).