Montmorillonite Clay in Dog Food

Montmorillonite is the common name for a type of clay composed of various minerals that are mined in Canada, China, and the southwestern U.S.

While this mineral has been used to promote intestinal health in humans, it might be harmful to dogs if present in foods at high levels.

The natural absorbent qualities of montmorillonite have made this clay popular with manufacturers of superabsorbent products such as diapers, sanitary pads, and cat litter.

However, its value as an intestinal-health supplement or ingredient for pet food is less clear — even controversial — according to veterinarians who spoke with VIN News Service about Clay.

Dr. Margaret Henningsson, head of product safety evaluations at Nestlé Purina Research and Development, said that while some animal nutrition scientists recommend it as a way to keep the colon clean and reduce fecal odor, others say there is little evidence montmorillonite clay works as claimed.

“Montmorillonite has been used as a source of dietary fiber in pet foods for several decades,” she said. “In general, dietary fibers are bulking agents added to provide additional structure or physical form to a pet food.”

Dr. Kathleen Jeglum Bartges, an associate professor at the University of Missouri College of Veterinary Medicine & Biomedical Sciences who specializes in small-animal internal medicine, also expressed uncertainty about the value of this mineral being included in canine diets.

“There’s no proven benefit from using montmorillonite clay,” she said. “There’s no evidence that it does anything at all.”

She added: “It certainly won’t hurt to add montmorillonite clay to pet food. To the best of my knowledge, it has no side effects.”

One person who finds scientific proof in favor of these mineral particles is Dr. Cynthia Harriman, director of animal nutrition research for Pet Food Institute, a trade association representing U.S. and Canadian companies that manufacture 95 percent of all commercial pet foods sold here.

She defined montmorillonite as an absorbent aluminum phyllosilicate ( aluminosilicate ) or smectite clay whose ability to form gels allows it to bind water and, as a result, keep feces moist.

“One of the challenges for dogs with inflammatory bowel disease is to keep the stools soft so they are easier to pass,” she said. “Clay can help bind water to stool.”

Because ingredients are listed on pet food labels by weight before processing, the amount of montmorillonite clay present will vary based on how much of it is used in making a particular product.

However, Harriman said there seems to be little difference between high-quality commercial foods that use this additive and more expensive brands without it.

“I think there’s some evidence that it works the way it promises to work, but I don’t know that you would necessarily pay more for a dog food because of that ingredient,” she said.

Is clay safe for dogs?

Dr. Henningsson noted that clay is also used in human infant formulas because it serves as an excellent source of minerals that are not yet fully developed in the young. She said, however, that there are reasons why dogs would not benefit from this ingredient.

“The presence of an undigested particle within the intestinal tract can potentially cause irritation and lead to inflammation,” she said, adding that this could also happen if the dog were to ingest one of these mineral-rich particles.

However, Harriman said such concerns seem unwarranted.

“There’s no evidence that (clay) is digestible once you get it into a processed food,” she said, “and dogs eat a lot of dirt.”

What does clay do to dogs?

Dr. Bartges said she was not aware of any clinical problems associated with dogs eating clay. She added, however, that some inexpensive dog foods contain lower-quality ingredients and may include ingredients such as poultry litter or feces.

“The concern is not so much the clay, but rather what’s on it,” she said about the latter possibility.

Dr. Lisa Freeman, a veterinary nutritionist in private practice in Naperville, Ill., and the author of several books about pet food ingredients said she has not seen any evidence that clay poses negative health risks to dogs.

She also added that there are no regulations governing products labeled as dietary fiber so manufacturers can market them however they want, be it as filler or beneficial.

“There’s nothing wrong with clay per se,” she said. “It’s just another way for pet food manufacturers to boost their fiber content .”

What is montmorillonite clay used for?

Pet Food Institute. It binds water to stool.

“One of the challenges for dogs with inflammatory bowel disease is to keep the stools soft so they are easier to pass.”

Harriman said there seems to be little difference between high-quality commercial foods that use this additive and more expensive brands without it.

“I think there’s some evidence that it works the way it promises to work, but I don’t know that you would necessarily pay more for a dog food because of that ingredient,” she said.

Is clay safe for dogs?

Dr. Henningsson noted that clay is also used in human infant formulas because it serves as an excellent source of minerals that are not yet fully developed in the young. She said, however, that there are reasons why dogs would not benefit from this ingredient.

“The presence of an undigested particle within the intestinal tract can potentially cause irritation and lead to inflammation,” she said, adding that this could also happen if the dog were to ingest one of these mineral-rich particles. However, Harriman said such concerns seem unwarranted.

“There’s no evidence that (clay) is digestible once you get it into a processed food,” she said, “and dogs eat a lot of dirt.” What does clay do to dogs? Dr. Bartges said she was not aware of any clinical problems associated with dogs eating clay. She added, however, that some inexpensive dog foods contain lower-quality ingredients and may include ingredients such as poultry litter or feces.

“The concern is not so much the clay, but rather what’s on it,” she said about the latter possibility. Dr. Lisa Freeman, a veterinary nutritionist in private practice in Naperville, Ill., and the author of several books about pet food ingredients said she has not seen any evidence that clay poses negative health risks to dogs.

She also added that there are no regulations governing products labeled as dietary fiber so manufacturers can market them however they want, be it as filler or beneficial.