Usually selenium is added sufficiently to concentrates, and less in roughage. The adding of extra selenium in supplements can be toxic if the total amount of selenium is too high. Because it is impossible to establish how much selenium a horse receives in his total diet, it’s too risky to add selenium to our supplements. A complete coverage without the risk of overdosing selenium isn’t possible in a standardized product. You always have to analyze the whole diet before adding selenium. Shortages of copper and zinc also play a role.
The EquilinBALANCER, GROW and IMMUNO do contain a good amount of well absorbable selenium, copper and zinc, and can be given as desired, the amount depending on the amount of concentrate that is being fed.
Symptoms of an acute overdose of selenium are:
Temporary blindness
Colics
Diarrhea
Shaking / shivering
Pain
High pulse and breathing
Sweating
Not feeling well
Symptoms of a chronic overdose (more than 6 mg per day for a grown horse) are:
Loss of main and tail
Loosening of the hoof wall
Symptoms of deficiencies of selenium (currently pretty common) are:
Problems with immune system or stiffness of muscles
Problems with coat and/or loss of colour of coat.