Selenium is essential for our dogs' good health. Its deficiency can be extremely damaging so complete foods must contain at least some selenium. It can come as a natural part of the ingredients (for example, sunflower seeds, many whole grains and most meats contain some selenium) but much more commonly, it is added as a supplement.
In the EU, only two forms of selenium supplements are permitted in pet foods - sodium selenite and inactivated selenised yeast (or organic selenium). While organic selenium is widely reported as more bioavailable and despite the fact that sodium selenite is classified by the European Union and the FDA as a toxic chemical, sodium selenite is far cheaper than organic selenium and therefore remains the selenium supplement of choice for the vast majority of pet food producers.
Of course, these companies will argue that the dosages of sodium selenite found in pet foods are much lower than those that have found to cause problems in lab animals (lung, kidney and liver damage and in some cases death) and they would be right. However, since no studies have been carried out on the effects of long term exposure to selenium selenite (it is, after all, given to many pets in every meal for their entire life) and since another, much safer alternative is widely available, we can't see any justification for the continued use of sodium selenite in pet foods.
Please note that sodium selenite is a mineral supplements and can therefore be listed under the general term 'minerals' or may not be listed at all. To find out if your dog's food contains sodium selenite, be sure to contact the manufacturer directly.
Find foods containing Sodium selenite See the full Ingredient Glossary