Does Your Pet’s Food Cause Cancer?


Pet caregivers rely on government oversight to protect their four-legged family members from pet foods that contain potentially harmful ingredients. We assume pet foods are nutritious, and more importantly, safe. Unfortunately, neither of these assumptions is true.

I have already written about nutritional issues with processed pet foods. Here we will explore a safety issue – namely the potential for pet foods to contribute to the pet cancer epidemic.

A recent study done by the Consumer Council of Hong Kong found that some dry dog and cat foods sold in the USA contain aflatoxin B1. This pet food contaminant is produced by molds that are commonly found in poor quality grains – just the type that end up in pet food.

Grain is the perfect growth media for mold. (If you don’t believe me just check the loaf of bread that’s been in the drawer for a week). There have been several pet food recalls in the past few years because of high levels of aflatoxin. At these high levels, this poison causes liver failure and death. Even the pet food industry frowns on this blatant carnage.

However, low levels of aflatoxin are acceptable by the pet food industry even though these small amounts are known to be carcinogenic (cancer causing). In fact, a Purina representative told the South China Morning Post that aflatoxin B1 was an “unavoidable natural contaminant” found in grains such as corn, barley, and rice.

Hey, I know a way to avoid this carcinogen – DON’T FEED YOUR PET PROCESSED FOOD! Dogs and cats were not designed to eat grains or other sources of starch for that matter.

Aflatoxin is only a small part of the connection between pet food and cancer. It is well known that heating meat and carbohydrates at high temperatures (as happens with the processing of pet food) creates heterocyclic amines which are a type of carcinogen.

A 2003 study found carcinogenic activity in 24 out of 25 commercial pet foods. The authors concluded, “From these findings it is hypothesized that there is a connection between dietary heterocyclic amines and cancer in animals consuming these foods.”

A more recent study found carcinogenic compounds from processed foods (specifically one called PhIP) in the systems of 14 out of 16 healthy dogs. These researchers concluded, “A potential role for PhIP in the etiology of canine cancer should be considered.”

It is time for pet caregivers to wake up to the fact that processed diets are not healthy for our pets. As a pet vet, I see cancer all too frequently. Some would have us believe that the reason cancer is on the rise in pets is because they are living longer. The fact is that I’m seeing cancer in younger and younger animals. I believe, and research agrees, that processed pet food is a major factor in pet cancer.

I am not suggesting that you start feeding some outlandish anti-cancer diet. I’m simply asking that you stop feeding a cancer promoting diet. In other words, go RAW!

Raw feeders out there – help me encourage conventional-feeding pet caregivers. Comment on your experiences with your pets.



43 thoughts on “Does Your Pet’s Food Cause Cancer?

  1. Micki

    When my heart dog had osteosarcoma, we switched him to a home cooked diet after I learned that carbs feed cancer. His oncologist didn’t recommend raw due to the reduced immune system but encouraged home cooking. When he died, I decided I needed to reevaluate my feeding methods. I switched to The Honest Kitchen foods and saw a great improvement in my other dog. When I got another dog, I decided to combine raw with The Honest Kitchen food. That was a great decision four years ago, and we’re still feeding the same way. My dogs look wonderful and have lots of energy. I would recommend it to anyone, and it’s easy!

  2. Chris

    I would like to know your opinion on how healthy Blue Buffalo Adult Lamb and brown rice is?
    My dogs really like it and this dog food seems to be fairly healthy. I have a 14 year old Lab and a 7 year old Lab/Golden mix. My 7 year old thinks she is a lap puppy and very active. My 14 year old is an old lady with bad back legs and possible unstable hips, too.
    If I were to change over to raw meat, how do I know how much to give them a day, how to change over to raw and what kind of raw meat do I give them and how many times a day do I feed them with it? So many questions about changing over to raw. What if I would change over to raw and it makes them sick or have the runs.
    Let me know,

    1. Dr. Doug Post author

      Hi Chris,
      I think Blue Buffalo is a good brand of dog food – for kibble. The problem is that kibble itself is not a healthy form of dog food due to the processing and excessive starch.

      I do not recommend a pet diet of raw meat. I recommend a balanced raw diet which would consist of meat, bones, organs, and shredded veggies such as Typically a dog is fed 1% – 3% of his body weight per day and I feed my pets twice daily. Change diets gradually and support the pet’s GI tract with probiotics and it almost always goes smoothly. There are detailed directions on the Answer’s Pet Food web site.

      Hope this helps!

  3. Amy

    We feed raw and have for a couple of years. Before feeding raw, our dogs ate a mix of very high quality canned food and kibble. They were generally healthy but did have the occasional issues – ear infections, gas, and each had a mild bout of acute pancreatitis.

    The switch to raw produced amazing results, even in already-healthy dogs. One thing most people don’t realize is that a “doggy” smell is not normal! Gunky ears, itchy skin, dark bellies (on pups whose bellies should be pink) – none of those are normal either. On a raw diet, my dogs don’t smell, don’t itch, and have very few visits to the vet besides regular check-ups.

    Raw feeding is almost as easy as feeding kibble when you select a great commercial raw product. If it’s more expensive, keep in mind that a healthier dog typically incurs less visits to the vet.

  4. Jeri

    Our older dog was “unofficially” diagnosed with IBD (we didn’t have a biopsy done to confirm the diagnosis). She would have horrible bouts of exploding, bloody diarrhea, but never acted “sick”. Because our (conventional) vet believed this was caused by an intolerance to some protein she had been getting and we didn’t know which one, we allowed her to be placed (temporarily in my mind!) on an awful Rx canned hydrolyzed protein diet. Over the course of a month and a half we weaned her on to a novel protein raw diet and it’s been 2 years and counting – no episodes!! I had already been “sold” on a raw diet, but we had had trouble getting around our older dog’s gastric issues. Once we switched to something she had never had before, it was like turning on a light switch! (We told our vet later what she was on; he didn’t approve but he can’t deny the results and at least he “tolerates” our maverick ways, lol!) We also have a holistic vet on our team – to whom she goes for acupuncture periodically. She’s 15 years old this month and acts like a pup! The only medicine she takes is for heartworm prevention because of where we live. There are many dogs in our neighborhood who are younger than she or her age, but I can tell what diet they’ve been on their entire lives. They are obese, on many medications and cannot get around well at all, much less act like our dog does. So sad. We try to spread the word every time someone comments on our dogs and how great they look. (Our other dog is 8 years old this year and we have saved his teeth with raw!) He had 4 infected teeth removed and our conventional vet was very nonchalant about the fact that he would probably lose more as time went by (there were a few “pockets” he was watching on the x-rays). I was horrified and decided to change his fate. Next x-rays he had – no problems visible and his teeth are FABULOUS!! This is one dog who will not need “doggy dentures” as he gets older!! We would NEVER switch back to kibble now — never never never!!

  5. Angela

    I recently switched over to raw after an abundance of health issues in my Yorkie/Maltese mix. I have seen amazing results. Her coat is much shinier. The amount of energy she has is insane. She has stopped the random vomiting and her acid reflux seems to be under control for the most part. Her stool seems much healthier too. Before the stool had a tendency to be a bit on the mushy side, and I knew it wasn’t supposed to be like that. Since she has firmer stool, it has also helped out with her anal gland issues as well. It has cut back on visits to the vet for sure.
    I had her on high quality canned foods for the past year or so, but the problems persisted no matter what brand I tried. It was one thing after another, so I eventually made the decision to try raw. I don’t think I will ever switch back. I am currently using Primal Venison formula and I also throw in a little Answers goats’ milk with every meal (if I don’t she pitches a little diva fit). She doesn’t seem to do well on chicken or beef so I have to go with the less common proteins when possible. I went with Primal because they do not use synthetic vitamins and have all natural organic ingredients. They also don’t get anything from China. The food is freeze dried so all nutrients are intact since the food is not heated. Also, they had something other than beef or chicken to offer. Their food comes in nuggets and patties so it is easy to portion it out into the right amount. I have found that low fat foods help with the acid reflux issue too, so the venison fit the bill. The rabbit does too, so we may try that next.
    Dr. Doug, what are your thoughts on Primal? Good choice or is something better out there? Do you have any other advice on dealing with acid reflux?

    1. Dr. Doug Post author

      I think Primal is a fine food and it seems to be working well for your situation. I believe they do use high pressure pasteurization – which I am not convinced does not change nutrients. My favorite food at the moment is Answers. (My pet food preferences change as the companies change their proceedures.)

      I’m not sure what you mean by “acid reflux.” I don’t know that I eaven believe in the term. Many suce digestive issues disappear when appropriate foods are fed. If not, then I apply Chinese medicine.

      1. Angela

        That is good to hear! They only use HPP on products containing poultry. I haven’t used any of those because of the HPP. I have looked at Answers, but like I said, she has an intolerance for beef and chicken. I think that only leaves pork as an option with them, which I had planned to try at some point. I like to change it up every once in a while. I know I would get sick of eating the same thing for months at a time. They don’t offer any other protein options besides those three correct? I just wanted to be sure I didn’t miss one!

        I find it interesting that you do not believe in the acid reflux. That is what our vet told us her problem was. He told us to give her pepcid once a day at bedtime. I did that for while, then realized pepcid could cause more harm since it contains NSAIDS. That is pretty much when I started my pet food quest. I wanted to fix the problem and not just treat they symptoms. In my research, I could not really find anything on acid reflux in dogs so I was starting to think he was a bit off on that diagnosis. She is otherwise healthy as far as we have been told, so hopefully it is nothing major. She still has a moment every now and then when she throws up. A lot of the times it is when there is longer than normal periods between meals (like if we sleep in on the weekends) and she throws up bile looking stuff. I am taking her to see a holistic vet for her yearly exam next month. The nearest one is 2 hours away, but I think it may be worth it. I am hoping to get her sorted out properly. We are also opting for titer testing to cut back on the vaccines and doing the three year rabies vaccine instead of the 1 year rabies vaccine. So wish us luck!

        Have a wonderful day!

  6. lisa


    I was wondering what your opinion of Merrick dog food is. I feed my dogs the grain free Texas beef and sweet potato formula. I didn’t see anything Suspect in the list of ingredients and my dogs seem to be doing quite well on it. I also feed them raw vegetables and berries instead of processed treats of any kind.

    1. Dr. Doug Post author

      I have to say that I’m not familiar with Merrick dog food other than knowing the name. Even nutritionists who follow the main brands of dog food find that the formulations change almost yearly and so they have to continuously update their lists. Since it is kibble the processing creates carcinogens and even though it is grain free, it has starch.

  7. Janine Tully

    I’m thinking of switching to raw food for my dog. I see you recommend Answer’s. Its website list decaffeinated tea as a preservative (?) I always thought that anything decaf is chemically altered. Also the patties have lots of protein and other good stuff, but what about vegetables and fruits. Do we add those separately. Raw/cooked.

    Thank you for your response.


    1. Dr. Doug Post author


      I’m sure that Answers does not chemically alter the tea but that is a great question to ask them. You can call their 800 number. The diet is meant to mimic the ancestral diet of dogs. It turns out that the predecessors of dogs did not eat much in the way of fruits and veggies, just like wolves today.

      Dr. Doug

  8. Gail Longhurst

    Very interested in but I live in the UK. Do you know any supplies in England please.


  9. Deanna

    Hi, We feed our two cats Blue Buffalo Wilderness, a combination of canned food and dry. All are grain-free. Would you still recommend switching to a raw food brand like Answers or Primal? Is one preferred over the other? Would love to hear your thoughts so we can discuss with our vet when we go next.

    1. Dr. Doug Post author

      A balanced raw diet is better than the best processed food. My preference is Answers. If your vet is conventional then there is not much point in discussing the switch to raw. There are very few who would not be hostile to the idea.

  10. Mike

    What are your thoughts on Orijen? I am feeding my dog Primal now, but Orijen does seem like a very high quality food.

  11. Michelle

    My 13 year old Shih Tzu has been diagnosed with a mast cell tumor on her paw and she is on Orijen Regional and I’m wondering if this is okay for her to be on or do I need to actually put her on a cancer diet and make her food.

  12. Kate

    My dog passed away from Squamous cell carcinoma of the tonsil. She lived an amazing 5 months from biopsy/diagnosis on the raw diet all her life. My Vet was always trying to get her off of it, hounding me about my own poor immune system and how dangerous it was to feed her raw. Most of her food was frozen, killing any bacteria. He told me she was a miracle but never attributed her unusual length of life with such an aggressive cancer to feeding raw. He recently told me one of the dogs in his clinic got the same cancer and it only lived 3 weeks from diagnosis. I do believe the raw diet is the best diet and gave us those precious extra quality months with our dog. On the day we said goodbye she was having trouble breathing because the tumor was affecting her vocal cords and airway….but she managed to try her best to chase a squirrel, do one more walk to the park and eat her raw breakfast. She never stopped eating a full meal. We knew she was suffering and didn’t want her to suffocate to death so we did the only thing we could and said goodbye. One day when I get a new puppy I will definitely feed it raw too. Some people tell me to just tell our Vet we are feeding a brand of food he approves of but I won’t lie, don’t let vets scare you from feeding your dog or cat what you believe in and what is proven to be the best food. Our cat is on the raw diet, has the most beautiful healthy coat, shiny eyes and no skin or weight problems. I believe in it, I encourage anyone to look into it. I even asked our dogs oncologist and she told me she truly believed in the raw diet. There are forward thinking Vets out there!

  13. Kimberley

    Hi I just wanted to say I was reading everybody’s posts and the reason for my post today, is because I have a 5 1/2-year-old fixed female Who is a boxer American bulldog. Three weeks ago , we noticed a lump on her left leg by the ankle area. We took her to our vet and they took a needle to it for a read on what it was. They called me on a Tuesday and said it’s cancer, I made an appointment that day for a surgeon 45 minutes from us, they took her in last Thursday and operated that afternoon. They took off a spindle cell tumor from her left leg and I found a small lump on her chest when we were discussing surgery with dr that morning, so that was also removed to biopsy. The one on her chest was a small mast cell tumor. So of course we were told that she has two different types of cancer, and our family is devastated. We take her back next Tuesday to have her stitches taken out and then have an appointment with the oncologist to speak to them about her treatment plan. Since I found out she had cancer , I have been feeding
    her a quarter cup of cottage cheese and 1 tablespoon of flaxseed oil three times a day. My reason for searching the Internet is because I want to change her diet altogether. Six months ago she was put on Hill’s prescription diet metabolic advanced weight loss solution ,she was overweight by 10 pounds . Otherwise she was a healthy dog ,blood work was always good never any problems, ever since this diet now this. I want to feed her a raw diet and would love
    for anyone to suggest how to begin this with her. We are only beginning this new journey with her, and hope to have her be a survivor for years to come. Thank you

    1. Dr. Doug Post author

      Start with a commercial raw diet (I like Answers). Feed 1/4 the amount of the raw food that she should eat along with 3/4 of her current diet. Do that for 1 week, then go 50/50 for 1 week, then 3/4, 1/4 for a week, then 100% raw.

  14. Kimberley

    Hi Dr.Doug,
    I will be starting this transition tomorrow with all three of my dogs. Thank you for the information , it is greatly appreciated . I will get back to you in a few months with updates.


  15. sherry hughes

    Hello. So happy that I found your website. We lost our 12 year old lab in September to bone cancer. So, so sad.
    We are buying a white english lab and he will be ready to come home in a few more weeks. I am so concerned about what to feed our new pup. We went with the traditional dog food because we honestly did not know better. I don’t understand how our dog got cancer in the first place. I want to make sure that we choose the best food for our new pup. I read on your website that you like the Answers raw diet. Would you please help me understand this? Thanks so much for your time.

  16. Marijana Dedic

    Dr. Doug can you please tell me the brand of probiotic you prefer? There are so many on the market . Thank you

    1. Dr. Doug Post author

      I like VetriScience products, especially VetriMega Probiotic. Also, Answers fermented goat’s milk.

  17. Jennifer

    We lost a 14 year old Golden Retriever to cancer this past December and we are adopting another dog soon. I read about a Border Collie that lived well past 20 years old on a vegan diet. I was giving my Golden the Dick Van Patten’s vegan dog food for a few months with some white rice because she would make in the house when she was older. I would like our new dog to also eat vegan or at least vegetarian, what do you think?

    1. Dr. Doug Post author

      I think that’s a really, really, really bad idea. Dogs are carnivores and are at their healthiest eating a balanced, raw, meat-based diet.

  18. Margaret Lane

    My cat was diagnosed with Lymphoma back in August of 2014. She had surgery and then 6 months of intense chemo. Her vet told us up front that there was no guarantees. We celebrated we thought two years in remission. Now she seems to be coming out of it. I have been feeding her friskies and fancy feast. The ultrasound that we had in February did not show any masses but the way she is acting makes me think that her cancer is coming back. At this point is there anything I can do to slow down the cancer if I switch her to eating better food and if so what can I switch her to. I am at this point ready to feed her just about anything besides the cheap cat food at Walmart.

  19. Dennis Eichers

    I have lost three dogs to some forms of cancer in the last 17 years. I have a 1-1/2 year old I am adopting in June and have decided to go raw. Have you had any experience with Steves Real Food? Seems very similar to your Answers food but is available locally for me.


    1. Dr. Doug Post author

      I do not have personal experience with Steve’s but if that’s what you can find I’m sure it’s better than processed food.

  20. Priscilla

    Thank you so much for this website. I recently lost my cat (17 years of age). He had a tumor on his side. that had grown to the size of an orange. I am at a loss as to what to feed my last kitty. He is 5 years old. I have been feeding them Science Diet MD because of my other diabetic kitty who passed in March of this year, also 17 years of age. Can I do anything to help insure that my last kitty stays healthy. I’ll even go raw.

  21. lna

    I have been feeding my cat boiled chicken mixed with canned food (wellness). They also eat kibbles (Core), which one of the cats love! I am thinking of including raw food in their diet rather than canned food. But, what do you think of boiled chicken? I have 2 cats and they are both 5 years old.

    1. Dr. Doug Post author

      Meat of any kind is not a balanced diet. I suggest replacing everything you are feeding with a balanced raw diet.

  22. Steve

    Dr. Doug, my English Bulldog just had an emergency surgery for pyometra and our vet told us afterwards that he removed two tumors and a nodule. He said we won’t know if they are malignant until the tests come back but we are preparing to do whatever we can to help her.

    She’s currently on Orijen Original and we are considering a switch to a raw diet like Answers but are concentrated about the bacteria risks and also the cost seems to be quite high as we have two dogs.

    Would doing one Orijen meal and one raw meal per day be a good way to reduce bacteria concerns, while helping with raw benefits and also reducing the cost?

    1. Dr. Doug Post author

      In the Case of Answer’s raw pet food, I am not concerned about bacteria. They use fermentation to cultivate probiotic bacteria that kill the pathogenic bacteria. It is unfortunate that real food has to be more expensive than cheap processed food (even the good brands). Of course getting one meal of real food per day is better than none at all. I hope all goes well for your dog.

  23. Angela

    I know that Answers raw food is your top choice and
    We may go that direction in the future. I wanted to know what you think about Honest Kitchen’s grain free dog food Force.
    The Honest Kitchen Human Grade Dehydrated Grain Free Dog Food.

    We have gotten off of kibble and have been feeding this and it seems to be going well. I just wanted to know what you think of this food.