Beware: Sodium selenite in pet food is toxic

By Cat, Jan 30, 2018

It is generally known that heavy metals are toxic; metals such as mercury, aluminum, cadmium, lead, arsenic and free-iron. Selenium is also a heavy metal, but it can be either toxic or safe, depending on its form.

  • It is an essential mineral for most animals, including humans, but only when it is present in organic forms (combined with a protein or amino acid); examples are selenium methionine and  selenium yeast (a form of nutritional yeast that has been grown on a diet containing selenium, incorporating it into proteins).
  • In other forms such as salts (e.g., sodium selenite, NaSeO3), it can be quite toxic, even in very small quantities. Also, as counter-intuitive as this sounds, it is a truth as found in various studies: the smaller the concentration of toxic selenium, the greater the harm because small concentrations mimic hormones, especially estrogen.

Sodium selenite is a common ingredient present in most pet foods that can be very damaging to the health of your dog or cat, even though it is present in very minute amounts. It may be toxic to your pet’s blood, kidneys, liver, skin, or central nervous system (2).

NOTE: If you take, or give to your pet, a multi-vitamin, multi-mineral, or specific mineral supplement that contains sodium selenite, stop using it and find a safer brand. For example, a widely used supplement for humans that contains this toxic ingredient is Centrum.

See also: Miscellaneous & Information Menu (scroll down to “Pets”)

Sodium selenite toxicity

Science Lab is a company that provides Material Safety Data Sheets (MSDS) about potentially toxic substances. Here’s what they have to say about sodium selenite (scroll to section 3 of the report (2), that is applicable to both humans and pets. Note that I have put part of the text in bold for emphasis:

“Sodium selenite… may be toxic to blood, kidneys, liver, skin, central nervous system. Repeated or prolonged exposure to the substance can produce target organs damage. Repeated exposure to a highly toxic material may produce general deterioration of health by an accumulation in one or many human organs.” (1,2)

I feed kibble (dry food) to my cats, but use only those brands that do not contain grains or soy which are known to be problematic for obligatory carnivores like cats. I just checked the two brands I am currently using and was shocked to see they both contain sodium selenite. I no longer buy those brands. One of my cats, Charlie, has kidney issues according to blood tests, and my other cat, Chloe, is also showing signs of the same trouble.

NOTE: You have to read the small print in the ingredients section, and look toward the end of the list. Here’s the list from one of the brands I’d been using; I put the sodium selenite in bold to help you spot it. Note that it does not include one of the safer forms: selenium yeast:

Trout, ocean fish meal, sweet potatoes, potatoes, pea protein, potato protein, canola oil, smoked salmon, natural flavor, choline chloride, DL-methionine, taurine, dried chicory root, tomatoes, blueberries, raspberries, yucca schidigera extract, dried Lactobacillus acidophilus fermentation product, dried Bifidobacterium animalis fermentation product, zinc proteinate, vitamin E supplement, niacin, manganese proteinate, copper proteinate, zinc sulfate, manganese sulfate, copper sulfate, thiamine mononitrate (vitamin B1), vitamin A supplement, biotin, potassium iodide, calcium pantothenate, riboflavin (vitamin B2), pyridoxine hydrochloride (vitamin B6), vitamin B12 supplement, manganous oxide, sodium selenite, vitamin D supplement, folic acid.

A better way to provide essential selenium in pet food is to add an organic form of selenium; selenium yeast is one of the least expensive, similar in cost to the toxic sodium selenite. The Truth About Pet Food (1) quotes from a scientific study (3), as copied below. Note that “Se” is the chemical symbol for selenium:

The simple solution, as recent science has proven, seems to be adding non-toxic selenium yeast to animal feeds including pet foods. “Of about one dozen supplementation studies, none has shown evidence of toxicity even up to an intake level of 800 microg Se/d over a period of years. It is concluded that Se-yeast from reputable manufacturers is adequately characterised, of reproducible quality, and that there is no evidence of toxicity even at levels far above the EC tolerable upper intake level of 300 microg/d.” (1,3)

I have written to the manufacturers of the food I’ve been using, asking them to replace sodium selenite with Se-yeast. I note that I have stopped using their products that contain  sodium selenite, the toxic form of this heavy metal. In the meantime, I’ve switched to Acana brand to augment their main diet of selenite-free Friskies and Fancy Feast canned food. (NOTE: not all of Friskies canned foods are selenite free, so read the label!). Because these foods contain no form of selenium, I add a sprinkling of Nutritional Yeast that contains Se-yeast to each serving of canned food.

Safe Brands of Pet Foods

The following is a list of commercial pet foods that DO NOT contain sodium selenite: (4)

Wet or dry brands:

  • BFF (Best Feline Friend) – All canned and Oh My Hydration pouches.
  • Fancy Feast
  • Feline Natural
  • First Mate
  • Friskies – Tasty Treasures line [Cat’s note: also certain other canned food]
  • Fromm – four-star canned [Cat’s note: Fromm kibble contains the toxic sodium selenite)
  • Fussie Cat – canned.
  • Hill’s Science Diet – most canned.
  • Nature’s Logic – canned and dry.
  • Sheba
  • Soulistic – Pate & Shreds, and Original canned. [Cat’s note: most versions contain sodium selenite per their website)
  • Tiki Cat – all the Grill canned foods. Some Luau.
  • Weruva
  • Whiskas [Cat’s note: contains corn, wheat and gluten]
  • Ziwipeak – canned

Dry only:

  • Acana 
  • Evo [Cat’s note: This product may have been discontinued by the manufacturer]
  • Orijen
  • Royal Canin – Aroma Selective dry.

The following brands of cat food contain a safer form (selenite yeast): (4)

  • Farmina dry (US formulas) [Cat’s note: see reference #5, below, for link to the grain-free dry food flavors that contain selenium-yeast rather than sodium selenite; it is available on Amazon]
  • Nutro (Hairball Control and High Protein dry only) Edit: Nutro changed their formulas. Used to be all dry formulas contained selenium yeast. Now only two dry foods have it.
  • Ziwipeak (canned or air-dried) [Cat’s note: per their website: canned contain no selenium at all; all air-dried contain sodium selenite, not Se-yeast. I sent them an email requesting confirmation. Their response is that their canned and kibble dog foods use se-yeast, but that form is currently not allowed in cat food by AAFCO regulations. AAFCO is Association of American Feed Control Officials]. My take is that they should still remove the sodium selenite.

Availability of certain safe brands in Flathead County

Aquarium Shop (home of Dog Food Express) in Kalispell

I just got the following information regarding sodium selenite-free pet food brands they carry or can order from their supplier. Their orders go in on Monday and would be in-store by Thursday of the same week. Located at 1001 East Idaho St (just east of the underpass); phone (406) 755-6000; open Mon – Sat, 11 – 6; and Sun 12 – 4.

The links in the list below go to the brand’s website, where you can get more information about each brand.

  • BFF (Best Feline Friend), canned in-stock; can order BFF Hydration Pouches.
  • EVO, dry; no grains, soy or potato; 2 flavors; cat/kitten: about $8 for 2 lb or $40 for 15 lb (can order)
  • Fromm, canned (can order)
  • Fussie Cat, canned (can order)
  • Nature’s Logic, canned or dry (can order)
  • Tiki Cat, canned (can order) [I don’t know if Tiki Dog is Sodium-selenite free]
  • Weruva, cans or pouches (can order)
  • Ziwipeak, air-dried (can order) [Cat’s note: their website indicates the air-dried flavors contain sodium selenite, and the canned flavors contain no selenium at all. Their response to my email: their canned and kibble dog foods use se-yeast, but that form is currently not allowed in cat food by AAFCO regulations. AAFCO is Association of American Feed Control Officials.]

Tail Waggers in Whitefish

I’ve not checked them out lately, but the last time I was there, they had Acana, dry, but it is not currently on their website; I’m told their supplier is not allowed to sell Acana brand in our state. They currently carry the following pet foods; I’ve noted whether they contain the toxic or safe form of selenium, but I still have a few brands to check out:

  • Fromm kibble for cats, dogs (contains toxic sodium selenite)
  • Open Farm for cats, dogs (contains toxic sodium selenite)
  • PureVita kibble for cats (contains toxic sodium selenite)
  • PureVita kibble or canned for dogs (contains safe se-yeast)



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