Copper Sulfate in Dog Food — Is It Safe?

Copper Sulfate on a Dog Food Label

Once again, concerns about the safety of copper sulfate in dog food appear to be making their way around the Internet.

So, many of our readers have asked if it’s OK to buy dog food that includes this ingredient in its recipe.

For the answer, let’s take a quick look at the facts.

Why You’ll Find Copper
Supplements in Dog Food

Copper is an essential mineral for dogs, cats and humans.

So, you’ll nearly always find some form of copper on a dog food label.

That’s because in order to legally claim a product is “complete and balanced”, a dog food must contain the right amount of copper to meet AAFCO1 nutrient profiles.

How Much Copper Is Healthy?

According to the official 2015 AAFCO publication2, a dog food must contain at not less than 7.3 mg of copper3 per each kilogram of dog food.

However, any mineral (even the sodium that makes up common table salt) can be toxic in excessive amounts.

The official maximum for copper is 250 mg.

Because some compounds of copper have such poor bioavailability for dogs, AAFCO does not permit copper oxide to be used to meet the association’s official nutrient requirements.

So, manufacturers must use copper sulfate…

Or a chelated form of the mineral, such as copper proteinate, copper complexed with an amino acid or polysaccharide…

To meet these guidelines.

Special Caution
with Liver-Rich Recipes

Some dog food ingredients naturally contain more copper than others…

Especially beef liver.

What’s more…

According to a more recent study

Indiscriminately adding a mineral supplement to any recipe could lead to an increased risk of copper toxicity.

That’s why it’s so important to avoid buying food from companies that do not regularly test their products for nutrient content.

The Bottom Line

The personal interest story that was recently published in a local news paper appears to base its warnings about copper sulfate on a hypothesis proposed by one well-meaning veterinarian.

And his theory is certainly worthy of further investigation.

Yet it’s important to keep in mind that as long as copper, or any other nutrient, is confirmed through testing by its manufacturer to be present in a dog food in a healthy amount, your pet should be considered safe.

For an enlightening scientific explanation on this topic, be sure to read this pet food industry article about copper sulfate.

It was researched and written by a respected animal nutritionist, Dr. Greg Aldrich of Kansas State University.

After reading Dr. Aldrich’s overview, you should be able to make a more informed decision whenever you notice copper sulfate on a dog food ingredients list.


  1. Association of American Feed Control Officials
  2. AAFCO 2015 Official Publication, p. 150
  3. Dry matter basis