The effect of injectable barium selenate on the Glutathion peroxidase activity of horses on pastures

Abstract

The aims of this study was to measure the response to i.m. inyection of barium selenate (Deposel) using erythrocytic glutathion peroxidase (GSH-Px) activity as indicator of selenium status. Local tissue reaction in the injection site was also measured. 
Fourteen Chilean Criollo horses, from two to twenty years old, low erythrocytic GSH-Px activity and under pasture feeding were used. They were divided into two groups: A (n=8) received a single dose of 0.5 mg/kg bw of barium selenate and B (n=6) received a placebo. Heparinizated blood was obtained at the beginning of experiment and at 30, 60, 90 and 180 days after treatment. Local tissue reaction was evaluated according to reaction size, discomfort on palpation, local temperature and lameness. 
Erythrocytic GSH-Px activity of the A group incremented thirty days after treatment, reaching the minimum value of the reference range (> 100 mU/mgHb). However, this increment was not statistically significant (p>0.05), but difference between treated (A) and non treated (B) groups were statistically significant (p<0.05). GSH-Px activity incremented significativelly 60, 90 and 180 days after treatment in the treated group, and differences between treated and non treated groups were also significantly (p<0.05) at these time. 
Treated horses showed only barely discomfort on palpation and a light local temperature elevation at injection site, but both of them disappeared four days after treatment. 
It can be concluded that a single i.m. injection of 0.5 mg/kg bw of barium selenate, will increment and maintain erithrocytic GSH-Px activity in the reference range for at least 180 days in horses. Besides, i.m. injection of barium selenate does not produce adverse reactions clinically detected at the injection site. Palabras claves: equino, selenio, esteatosis, selenato de bario.