Controversial Ingredient Added To Hill’s Science Diet Has Dog Owners Concerned

As a diligent pet parents, you probably know what foods are dangerous for your dog to eat.

Chocolate and caffeine are among the top of the list, and grapes are known to be toxic for our canine pals. So, what is an ingredient like “dried grape pomace” doing in commercially-available dog food?

Image Source: Toxic Dog Foods Refrigerator Magnet via iHeartDogs


According to the ASPCA:

“Although the toxic substance within grapes and raisins is unknown, these fruits can cause kidney failure. Until more information is known about the toxic substance, it is best to avoid feeding grapes and raisins to dogs.”

Susan Thixton, who’s well known in the advocacy world for exposing secrets and educating people about the pet food industry, shared an article on her site,

In the article, Thixton discusses how pet store owner Fiona Macken learned that certain varieties of Hill’s Science Diet food contained “dried grape pomace,” prompting the two to do a little investigating. After doing more research, they discovered that the following varieties list this ingredient:

Image Source: Screen Shot via


Thixton points out that there may be others. (If your dog has become ill after eating any of these foods, you can report a complaint to the FDA by going here.)

Macken looked up “dried grape pomace” in her  AAFCO Official Publication (AAFCO is the association that regulates pet food). Thixton reported:

“Knowing her pet food regulations, she knew that each and every ingredient included in any pet food must be legally defined. Tomato and apple pomace are defined, but grape pomace is not. Next Fiona turned to the FDA website for ingredients Generally Recognized as Safe (GRAS) in animal food. The ingredient was not listed as GRAS.”

Image Source: Screen Shot via Dog Food Advisor

Macken then went directly to Hill’s Science Diet to ask about the safety of “dried grape pomace.” The company responded by giving her the link to a safety study for “mixed grape and blueberry extract.” Still, this didn’t provide evidence for the exact ingredient in question.

Thixton went on to consult with Mr. Richard TenEyck, the AAFCO chair of the Ingredient Definitions Committee, who confirmed that “‘dried grape pomace’ was not defined by AAFCO (thus it should not be used in any pet food).”

Last, the pet food advocate reached out to the FDA and spoke with Dr. Dan McChesney, Director Office of Surveillance and Compliance, Center for Veterinary Medicine. According to Thixton, he responded:

“Companies, both human and animal food, can and do self-determine GRAS [Generally Recognized as Safe.”

In essence, companies can determine if their own ingredients are safe, but the fact still remains that “dried grape pomace” is not defined by AAFCO. Therefore, it should not be used in dog food.

Because of Macken and Thixton’s diligence, foods containing this questionable ingredient may be pulled from shelves. She reports:

“Kentucky (a state Hill’s Science Diet has a plant in) Department of Agriculture representative Darrell Johnson stated ‘We have reviewed the label and will be contacting Hill’s requesting they remove grape pomace (as it is not an approved ingredient) from the formula and provide a revised label.  If they fail to remove grape pomace as an ingredient, the product would be subject to a ‘withdrawal from distribution’ order per KRS 250.591.’”

Because of people like Thixton, changes are being made to (hopefully) make the pet food industry safer and more transparent. In the meantime, it’s imperative that we as pet parents do our research and are diligent about reading the ingredient labels on our dogs’ food.

Thanks to Susan Thixton for being the voice of the consumer. Check out her site,, for information and resources.

(h/t: Truth About Pet Food)