Cancer causing compounds in pet food

There is a lot of discussion regarding the safety of feeding processed pet food. I've heard many claims about the fact that there aren’t many clinical studies conducted connecting pet food with health issues of dogs and cats. Some argue that if you can't see the "smoking gun" conclusive connection, then it's fair to say that the foods are safe for feeding.

Personally, I don’t believe in this type of thinking. And for me, the connection between the consumption of processed food and health ailments is clear.

I'm not writing this in order to intimidate you; Because you anyway hear every day how some food ingredients are not healthy. Rather, I'm here to provide you with information that will enable you to make educated nutritional choices for your four-legged family members.

You are free to think for yourself and find what you believe in and what is right for you and your pet.

Let's examine the available data in a logical way

Known information –

1. Pet food (canned and dry) is processed using extreme heat temperatures.

2. Pet food contains proteins and sugars (from carbohydrates).

3. Heat processing of proteins and sugars produces cancer-causing compounds.

Logical conclusion –

1. Heat treatment of proteins and sugars in pet food produce cancer-causing compounds.

2. Therefore, pet food contains toxic cancer-causing compounds.

Now, allow me to elaborate and explain in detail about each point.

Pet food (canned and dry) is processed using extreme heat temperatures

The most common pet food is dry kibble which underwent extrusion. The extrusion process leads to the formation of a dense food pallet, almost completely dry (mostly with under 10% moisture), and with a long shelf life.

The extrusion process includes mixing the wet and dry ingredients together in a heated food blender until the formation of dough. You can think of the extruder as a giant heated meat grinder (a few meters long).

The dough travels using pressure and under the intense heat of between 120-160 degrees Celsius. At the end of the machine, the dough passes through cutters which give the desired shape. Finally, the kibble is quickly chilled and sometimes sprayed with fat combined with flavors and a nutrient premix.

The second most common pet food is canned or pouched food. First, the base is made by boiling liquid stock with nutrient premix, oils, and different synthetic additives. While mixing and cooking, meat and vegetables are added. The mixture is then moved and the cans and pouches are filled, sealed, and undergoes cooking and sterilization which is called retort. Retort is cooking under pressure at temperatures ranging from 121-250 degrees Celsius for up to an hour.

As you can see, the most common manufacturing processes of pet foods involves using extreme temperatures.

Pet food contains proteins and sugars (from carbohydrates).

All dog and cat foods contain proteins and carbohydrates. Proteins can be from animal origins, such as chicken, fish, or beef; Or from plant origins such as peas and soy.

In addition, in order for the kibble to keep their form and the ingredients to bind together, manufacturers have to use starches. Hence, pet food contains carbohydrates such as rice, corn, and potatoes.

As opposed to kibble, in most cases, canned pet food won't contain carbohydrates. And if it will, they will be in very small percentages. Canned food is almost completely based on proteins with little vegetables.

The digestive system of cats and dogs break the proteins into their building blocks, amino acids; And carbohydrates into theirs, sugars.

Heat processing of proteins and sugars produces cancer-causing compounds.

According to the NCI (national cancer institute), using high cooking temperatures creates chemical reactions among amino acids, creatines, and sugars. These reactions produce dangerous carcinogens and mutagens that may damage DNA (human and pet alike).

Some of the compounds include:

· Heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs)

Created when creatine and amino acids (both found in meat) react together with heat at temperatures over 212 degrees F (100 C). Basically, the hotter and longer meat is cooked, the more HCAs and PAHs are created. Raw foods or food cooked at low temperatures, don’t contain HCAs or PAHs.

· Advanced glycation end products (AGEs)

Formed by what is known as the Maillard reaction, which occurs when sugars and proteins in the food react together to heat. Diets with more raw foods typically contain minimal AGEs.

· 2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP)

A heterocyclic aromatic amine (HAA) that is formed by the reaction of creatine and phenylalanine during high-temperature cooking of meat, poultry, and fish.

· Acrylamide

A compound also resulting from the Maillard reaction. Formed when asparagine reacts with naturally occurring sugars in high carbohydrate/low protein foods subject to high cooking temperatures starting at 248 degrees F (120 degrees C).

Why should we worry about these compounds?

HCAs are on the official list of cancer-causing agents published by the NIH. Studies have shown that exposure to HCAs, PAHs, and PhIP can cause cancer in animal models. In many experiments, rodents fed a diet supplemented with these compounds developed tumors of the breast, leukemia, colon, liver, skin, prostate, gastrointestinal tract, and lungs.

Once consumed, AGEs were found to contribute to a number of ailments. These include inflammation, atherosclerosis, kidney damage, neurodegenerative disease, muscle loss, cancer cell metastasis, insulin resistance, and alterations in cell receptors.

In addition, current research indicates that acrylamide may be genotoxic, carcinogenic, neurotoxic, and creates reproductive problems. It’s currently classified as “probably carcinogenic”.

Of course, it is needed that an animal consumes these compounds on a regular basis in order for them to accumulate in the body and potentially cause harm. Even still, many pets will show no sign of ailment even after been fed kibble for their entire lives.

It is important to look at the entire picture and understand that these compounds are present in pet food and the possibility that they may lead to future harm.

Connection to pets

A study conducted by the NYS Department of Health and the University of Minnesota had identified PhIP in the fur of 14 out of 16 healthy dogs consuming different brands of commercial pet food. The levels of PhIP in canine fur were comparable to the levels of PhIP present in human hair (of meat-eaters). However, high-density fur containing PhIP covers a very high proportion of the body surface area of dogs, whereas high-density terminal hair primarily covers only a small portion of the human body. These findings signify that the exposure and bioavailability of PhIP are high in canines. The researchers agreed that there is a potential role for PhIP in the etiology of canine cancer.

Another study published in the journal Mutation Research, analyzed 25 commercial pet foods for mutagenic activity. All but one gave a positive mutagenic response. Fourteen of these samples were analyzed for heterocyclic amine (HCAs) mutagens/carcinogens and all but one contained (MeIQx) and 10 of 14 contained (PhIP). From these findings the researchers agreed that there is a connection between dietary carcinogens cancer in animals consuming these foods.

What we can do?

For humans, currently, there are no guidelines addressing the consumption of foods containing these compounds. There is only a recommendation to limit consumption of processed meats.

As concerned loving pet owners, it's our responsibility to be well informed and we can choose to reduce their exposure to these compounds. This we can do by feeding our pets different foods that have been manufactured using lower or no heat treatment methods. Such as boiling, stewing, dehydrating, freeze-drying, or steaming.

Also, by adding fresh and steamed vegetables to our pet's diet, we can help remove HCAs and PAHs from the body and decrease the extent of DNA damage and oxidation of the cells via detoxification of the liver.

In conclusion, I'm not saying that every pet eating processed pet food will get cancer or other ailments. But, there are pets with predisposition which may be at risk. Or pets with a weak immune system, and adding to it these compounds will just stress it even more.

And, in general, like we are told that daily consumption of processed foods isn’t good for us, the same goes for our pets.


Sivan is a clinical pet nutritionist and a HACCP food safety team manager. She has been working in the pet nutrition field since 2010; while formulating and managing herbal remedies as well as dehydrated dog food. Along with being a pet parent herself, she consults to pet-owners and pet food manufacturers with the formulation of pet food and treats and lecturing on natural pet nutrition. She is closely allied with Paw Kitchen as an on-board nutritionist.