I always love checking out labels and looking into the ingredients of dog products that go in or on our pets. Recently, I’ve been looking at dog dental products, as there seems to be a rash of slick marketing campaigns aimed at our pet’s teeth. You are probably being bombarded with “use this treat” or “add this to their water” on a regular basis – if you don’t, surely you don’t love or care for your pet enough.

But what is in this green goop or blue chew stick anyway? Recently I examined an ingredient in a dog dental water additive that had a couple of questionable ingredients.

Today we’re looking at Sodium Hexametaphosphate, an ingredient that is being used in pet products including dental treats and food. This ingredient is the active ingredient of a new pet dental stick currently making the rounds on pet blogs. Sodium Hexametaphosphate is being marketed as a benefit, said to reduce tartar and plaque buildup. This additive is the active ingredient in many “dental care” kibbles on the market, and dental treats. So what is this active ingredient? Let’s look a bit further.

Do note I’m not a scientist, and I am researching scientific studies that are posted online and wrapping up that research in this post. Please refer to the studies I link here, or your own common sense, and draw your own conclusions about what you want to feed your pet. This is my opinion only.

What is Sodium Hexametaphosphate, and does it belong in a dog treat?

Sodium Hexametaphosphate is an emulsifier, sequestering agent, and texturizer. It is used to prevent scale formation and corrosion, and to prevent the appearance of a product from changing. It is also known as Graham’s Salt, HMP, SHMP, a “polyphosphate salt”, and by several other names.

This chemical ingredient is used in all sorts of things, and is generally known as a food additive for many foods in your fridge and pantry. However, it is also used to treat water, in detergent, soap, metal plating, remove scale, to create polymers… and your dog’s dental treats.

According to BeFoodSmart.com and the Material Safety Data Sheet (MSDS) for sodium hexametaphosphate, it carries the following risks:

In animal studies, the following effects were reported: pale and swollen kidneys, increased kidney weights, bone decalcification, muscle fiber size changes, hyperplasia and severe skin irritations.

The chemical can be hazardous to humans if ingested, and slightly hazardous on contact. You can find out more about the health risks in this study, or the MSDS.

In foods that contain SHMP, DogFoodAdvisor.com advises visitors that the additive is “a man-made industrial polymer with no known nutritive value….we’re of the opinion that food is not the place for tartar control chemicals.” This is also echoed by veterinarian Dr. Marty Becker, who writes “Rather than roll the dice on a commercial “dental care” pet food or treat that won’t, by itself, keep your pet’s mouth healthy (and quite likely isn’t optimally nutritious), I recommend taking the following steps instead” and lists several other options, such as brushing, oral exams, and a raw diet (however, do be aware that bones can lead to bowel perforation and peritonitis in a small percentage of cases… like my dog Mort).

Long term chronic effects of consuming this chemical

While several sources state that long-term low dose of this substance causes cancer, I could not find a study to support this. In fact, I couldn’t find a substantial study that discussed or evaluated the long term consumption of this additive in humans or any other species, or the potential effects of bio-accumulation. However, according to this Material Safety Data Sheet, it’s a potential concern for this additive:

Substance accumulation, in the human body, may occur and may cause some concern following repeated or
long-term occupational exposure.

In long-term animal studies, inorganic polyphosphates produced growth inhibition, increased kidney weights, bone
decalcification, enlargement of the parathyroid gland, inorganic phosphate in the urine, focal necrosis of the
kidney and alterations of muscle fibre size. Inorganic phosphates have not been shown to cause cancer, genetic
damage or reproductive or developmental damage in animal tests.

Considering this passage, I’m incredibly concerned (for both us and the pets) about long-term consumption of this additive that’s essentially a polymer. The “longer term” studies noted seem to be in the 6 month range, which doesn’t seem overly comprehensive. I think it’s fairly safe to say I plan to avoid Sodium Hexametaphosphate going forward.

What about added color?

Some dental products also contain Titanium Dioxide, which also falls into a “not studied enough and potentially harmful when consumed” category. For more information on Titanium Dioxide, keep your eyes peeled for an upcoming article discussing this ingredient.

So is it safe or not?

With the “internet research” I performed I cannot say I feel that it is safe, or worth the risk. The study of long-term small doses, which could equal what’s in this product, does concern me due to the potential for bio-accumulation as noted in the MSDS. And for that reason, in addition to it being a chemical, the product would be a no-go for me personally.

So make sure you look past the marketing campaigns on pet blogs and make sure you read the labels and get a good idea of what you’re feeding your own dog. Don’t discredit small amounts or the weird-sounding ingredients near the end of the list. Be wary of marketing. At least this product isn’t being marketed as “natural” this time.

So that’s a thing… but does Sodium Hexametaphosphate even work in dental products?

In this study of this active ingredient’s effectiveness in squirrel monkeys, it was found to not help unless the teeth were pre-cleaned. It was found that:

At the end of 6 months, dental calculus did not differ significantly between the experimental groups. Therefore, we conclude that HMP is ineffective in squirrel monkeys with preexisting dental calculus.

So sodium Hexametaphosphate may be useless unless you perform a dental cleaning first

So then I found the study on dogs specifically. The study involved 27 Beagles who “received an initial dental prophylaxis” (a cleaning). So yes – this product might work, but only after you clean your dog’s teeth, and use these treats with these questionable ingredients regularly. If you don’t do that dental cleaning, studies show you’re probably wasting your money. But at any rate, your pet might be a science experiment if you choose to provide this unnatural additive for oral health.

About Author

Jen deHaan is graphic designer, small business owner, and dog person living in Bay Area, California. Jen enjoys learning about dog training and behavior, and has taken several courses and seminars since 2010. She also contributes articles to leading websites, such as Victoria Stilwell's Positively . It all started with a great dog called Mikey (aka "dude"), loved and lost but remembered forever. Jen also runs a freelance business focusing on graphic, web, and UI design at FoundPixel, and a small business creating hand crafted dog products at Stylish Canine.