The Dangerous World of Dog Food Preservatives

by Mike Sagman
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Artificial preservatives might just be some of the most dangerous ingredients in dog food.

Here’s why…

Since animal fats are a crucial part of every dog food, they’re also subject to going bad… becoming rancid shortly after manufacture.

To extend the shelf life of any dog food, manufacturers nearly always need to add a preservative to each product.

But here’s the problem…

Preservatives can be either natural… or artificial.

Natural preservatives are usually made from anti-oxidants… like vitamins C or E. You’ll see them printed on a dog food’s ingredients list using some form of the word “tocopherol” or “ascorbate”.

Look for something like…

“…chicken fat preserved with alpha-tocopherol”

In general, natural preservatives are considered fairly safe.

Banned from Cat Food… OK for Dogs?

But artificial preservatives are another story. Used long term, they add a notable risk of toxicity to any dog food.

For example, take the moisture preservative, propylene glycol. You may recognize propylene glycol by its more infamous use in certain types of non-automotive anti-freeze.

Now, to be fair, this chemical is considered far less toxic than its more dangerous cousin, ethylene glycol.

However, due to its proven risk of blood toxicity, propylene glycol has been banned by the FDA for use in cat food.

Yet it’s still used as an artificial preservative in dog food.

Dog Food Preservative… or Dangerous Pesticide?

Now, here’s another artificial preservative you should be on lookout for… the chemical additive ethoxyquin.

Ethoxyquin is not only used as a dog food preservative but it’s also used as a pesticide… and a hardening agent in the manufacture of synthetic rubber.

Ethoxyquin has been under investigation by the FDA as a possible cause for certain types of canine liver and kidney cancer.

Yet to this day, it’s still commonly found in many popular brands of dog food.

Here are two more chemical bad guys to watch out for…

The World Health Organization openly names both BHT and BHA as suspicious cancer-causing compounds.  Plus the State of California now identifies BHA as a probable “carcinogen”, too.

With their troubling reputations for causing such serious disease you’d think these two nasty preservatives would be intentionally shunned by the pet food industry.

But, sadly enough, both BHA and BHT can still be regularly found in a number of commercial dog foods.

The Bottom Line

Dogs are a captive audience. They have no choice but to eat what we put in front of them. The same food…

Day after day. Week after week. Year after year.

It’s that cumulative exposure that worries me. The additive effect of using any artificial preservative relentlessly… especially when it’s suspected of causing cancer.

My best advice…

Avoid dog foods made with artificial preservatives.

Here’s a list of some of the more common chemical additives…

Who knows? Avoiding these dangerous dog food preservatives may just add years of good health to your pet’s life.

Notes and Updates

02/09/2009 Original article
08/15/2010 Article updated

Dog Food Advisor IconThe Dog Food Advisor publishes independent reviews to help pet owners make better choices when shopping for dog food.


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  • teresa

    I got two poodles 2 months ago and didn’t know what to feed them that was the best so I searched the internet on all dog food ingredients and what they meant. It’s really terrible what is on the market to feed our dogs. The very best I have found so far is (BLUE) which I am feeding to my dogs right now. Pet Botanics Healthy Omega is another good one. In these are no grains, fillers, by-products, artificial colors, synthetic preservatives and some of the other ingredients that I have research are not in them also. Since my poodles needs some weight gain and so they will eat their food better, I also put some meat from Pet Botanics that’s in the roll in their dish and they eat every bite then.
    I also found out every treat I was giving to them have terrible ingredients that I didn’t know about until my research. So I also cut up the meat and give them as a snack because I know its not bad for them. This dog roll are ideal for delivering a full canine diet where the majority of protein is derived from real meat. I also give them (blue) snacks, not the meat but with fruits and yogurt in them.
    All this food and snacks are more expensive but my PETS are worth a little bit more for their health and the love they give back to me in return.
    Here are a list of things to look for in dog food ingredients that I have found to be very bad for them and will eventually kill them.
    MENADIONE, CHELATED, PROPLENGLYCOL, ETHOXYQUIN, PROPYLENE GLYCOL, PROPYL GALLATE, BHA-PUTYLATED HYDROXYANISOLE, BHT- BUTYLATED HYDROXYTOLUNENE, ETHOXYQUIN, TBHQ,TOCOPHEROLS, TOMATO POMACE is a by-product. These have been known to cause different cancers in animals especially liver and kidney. Some of the are even pesticides.
    Avoid artificial preservatives and colors, corn, soybeans- these are a by-products which is a no no, cereal grain – product, animal fat, corn gluten meal, poultry-by-product-meal.
    I’m sure there are so much more as I learn more about this that I will be letting pet owners be aware of.
    Here’s hoping for the best for our little ones and a life time of happiness.

  • http://www.whosyourvet.com Sandi
  • Tina Summerell

    This website has been extremely helpful when searching for the best can and dry food for my precious dogs. I recently adopted two adorable kittens. Is there a similar website for cats/kitten food? Thanks!

  • Ashleah Vogel

    I appreciate all the information here, here are a few “safe brands” that I gladly recommend to anyone. Precise, First Mate, and Evangers. Precise is one of the only dog food companies that tests their ingredients as they come in to be processed, and when they’re finished to check that they are still balanced in the final product. First Mate is out of Canada and there are few stores that carry it, but it’s an excellent brand. Evangers is relatively popular and isn’t grain free but no corn, soy or wheat is used and it tends to do very well for most dogs. First Mate has a grain free line and Precise should be coming out with one with in the next year, hope this is helpful for recommendations!

    Ashleah

  • http://DogFoodAdvisor.com Mike Sagman

    Hi Marcy… According to Diamond Pet, (makers of Canidae), these foods do not contain ethoxyquin. Here’s a copy of the letter I received from the company’s staff veterinarian on July 7, 2010…

    “We are now using naturally preserved fish mean in all of our products. Even prior to the transition to natural mixed tocopherols (vitamin E), there were absolutely no health risks involved with feeding any of these foods. The switch to mixed tocopherols to preserve our fish meal was a response to customer demand. Fortunately, we were able to secure a supply of naturally preserved fish meal and shelf life studies have proven that we are able to maintain the product’s freshness throughout the shelf life of the product.

    “Homeland security does outline preservation using ethoxyquin, however alternative methods of preservation are available by special request. Our supplier has obtained all the required permits in order to use the natural preservative instead of ethoxyquin.”

    Janet L. Rettenmaier, DVM, MS
    Director of Veterinary Services

    According to a follow-up call with Diamond, the company made the switch to ethoxyquin-free fish meals in all of their products (Canidae, Kirkland, Diamond, TOTW, Chicken Soup for the Dog Lover’s Soul and others) as of May 2010. Hope this helps.

  • Marcy

    I appreciate all the information you are providing for us… it’s a confusing world out there in the arena of dog food. I have used Canidae All Life Stages for a couple of years and my dogs have thrived on it – they look and feel great. Then I heard about Ethoxyquin and started to do some reading on line. I was under the understanding that the supplier to Canidae is Diamond and that they do use ethoxyquin in their foods. I emailed Canidae and they told me that they do not use ethoxyquin nor do their suppliers. I’m confused. Can you help?

  • Pam Williams

    Hello Mike: First off just wanted to thank you for your efforts in trying to educate pet owners of the dangers in commercial dog found. Over twenty five years ago I read a great book by Dr Wendell Belfield called How to Have a Healthier Dog. He was a Vitamin Vet in San Jose Ca.(Retired now) What you have talked about he was stating and warning clear back then. He warned about the use of BHA & BHT, how the commercial dog food companies were using waste from the slaughter houses, and of the rendering plants that use dead cats and dogs. How sad that this book has been out there for so many years yet so few know the dangers of most of the dogs foods out there. Back before commercial dog food my Grandparents raised Collies and all they fed them was table-scraps and raw foods the dogs lived into there twenty’s. So over the years I have tried to teach people to read the ingredients and to be wise in selecting their dogs food. Because what they find in their dogs food they will also find in their children’s food, and look at the allergies and illness our kids are having today. So thank you again Mike for all your doing to help bring awareness to people out there.

    Pam Williams
    The Hitch’n Post
    Dog Training Center

  • http://DogFoodAdvisor.com Mike Sagman

    Hi Sara… Yes, according to the Blue Buffalo website, their fish meals are ethoxyquin-free. Unfortunately, I’m not aware of a cat food website similar to our dog food site. Hope this helps.

  • Sara

    Hi Mike,

    Two questions for you:
    1.) I recently switched my dogs over to Blue Wilderness Salmon and I was wondering if you know if this food contains ethoxyquin and, if so, if it is an amount to be concerned about?
    2.) Is there any equivalent version of your website available rating and comparing cat foods? There appears to be a lot more (and a lot clearer) info out there dealing with dog foods than cat foods…

  • Teresa Best

    Chris,
    I know there is not any fish or meat meals that contain preservatives in Dr. Harvey’s canine health & veg-to-bowl, because they don’t come with meat. That’s what makes it such a great dog food. It is a freeze dried mix which you add hot water to. Then after 8 minutes you add whatever protein (meat, beans, or eggs) you would like either raw or cooked & 1 tablespoon of oil, and feed it fresh to your dog. Check out their website, and you’ll see what I’m talking about. http://www.drharveys.com

  • http://DogFoodAdvisor.com Mike Sagman

    Hi Chris… This is indeed a problem (for us, too). I’ve never seen this information on an ingredients list. But many manufacturers (on their websites) do state when their fish meals are “ethoxyquin free”. If they don’t say so, you should assume ethoxyquin is in any dog food that has fish meal. I usually try to find out when I can (sometimes by calling customer service). Then I report my findings in directly in our reviews. Hope this helps.

  • chris B

    How do you know if the pet food manufacturer has or has not used fish or meat meals that contain preservatives. They dont have to put the preservative on their dog food label if THEY didnt add it, ie if it already came with the preservative?

  • Teresa Best

    I believe that anyone that has a pet in their life should feed them nothing but the best. Dr. Harvey’s pet products are made of human grade ingredients and NO PRESERVATIVES. The preservatives in the pet foods today, are probably killing our pets. Make the switch like I did, and I will guarantee your pet will be much happier & healthier.

  • http://DogFoodAdvisor.com Mike Sagman

    Hi Harley… I can understand your frustration, here. But since I’m not a veterinarian, I’m not trained or licensed to provide specific advice for treating a particular health condition with a particular dog food.

    However, there are a number of very good dog foods specifically designed to support GI health. Try clicking on the Tags item on the top menu bar of our website. Then click on the link labeled “Digestive”. This will give you a list of product lines that contain at least one product claimed by the manufacturer to be appropriate for GI conditions.

    Run your choice by your vet and be sure to transition very gradually into the new food over the course of a week to 10 days. Hope this helps.

  • Harley Liss

    Hi Mike,
    I have a 13 year old male Vizsla. Becuase of a recommendation from my Vet over five years ago, I have been feeding him IAM’s low residue vet formula dry food. Recently this food was recalled and my vet suggested I use Hill’s gastro-intestinal formula. The Hills brand smelled so foul, that I started to google the food to get more info and found your website. Low and behold, you rate both the IAM’s and Hills formula’s only 1 star! :( I had absolutely no idea how bad the ingredients were in these foods until I found your site. But now… I need/want to find a dry dog food that is five stars and also addresses the low residue digestive health. Do you have a recommendation? I would also like to find a canned food to mix into the dry – I’m still using the Iam’s low residue canned. Can you give me some ideas of what to try that I can buy in Chicago? Thanks so much.

  • Casey

    I used to work at a food manufacturing plant in Michigan. We had certain barrels used for floor sweepings. Food mix, dirt, dust, wood chips and splinters, paper bits, metal shavings, etc. are swept up all the time. I found out that those barrels were sent to animal food places, for use as dog food and pig feed. I wanted to know which company bought this stuff, but they would not tell me. That was 10 years ago. I wonder if this practice still goes on today..

  • http://DogFoodAdvisor.com Mike Sagman

    Hi Tim… Thanks for your comments. However, I’m concerned that you may not have read the links in this article. Since other readers may do the same, I’ve updated this article to reflect some of the information covered in the linked posts.

    First, propylene glycol is indeed an anti-freeze. To be fair, this anti-freeze is far less toxic than its chemical cousin, ethylene glycol. In any case, propylene glycol has been shown to be toxic to dogs in larger doses… with a 50% chance of being lethal at doses of 9mL/kg (Peterson, Michael; Talcott, Patricia (2006), Small Animal Toxicology, St. Louis, Saunders Elsevier, p. 997)

    As I mention in my article about the chemical, although it is believed to be safe in smaller amounts, “it’s the continuous, day-after-day feeding of this controversial chemical that worries me”.

    Next, although BHT has been approved at controlled levels in cosmetics and some foods, the Select Committee of the FDA (2006) warns “uncertainties exist requiring that additional studies should be conducted”.

    Again, our concerns lie in the long term, daily use of BHT in food (not cosmetics).

    And finally… yes, even fat soluble vitamins can be toxic to the body. But the daily use of normal doses of vitamins (essential for life) are a far cry from the long term use of non-essential (and unnecessary) synthetic preservatives like the ones mentioned in this article.

  • tim villalobos

    Me thinks most anti-freezes are ethylene glycol not propylene glycol so don’t go off the deep end with that. Also polyethylene glycol is used in a lot of foods too. So not all gylcols are the same. Many of them are used for people foods, pharmceuticals, cosmetics, etc yeah but not ethylene glycol. That stuff is toxic to people and critters. Wiki it if you like…

    Also BHT is a common and powerful antioxidizer used to prevent rancidity in fats, oils, etc. Heck it is many oily, fatty foods that people eat. It is a great way to preserve cooking oils to extend their shelf life. It will even preserve gasoline in underground storage tanks – that is how strong this stuff is. I would be very careful with it but not treat it as persona non grata. It can help keep dog food or people food from becoming rancid unless you freeze it. I would rather not use frozen dog food; very inconvenient.

    Personally I use “Wolf King” dog food because it doesn’t have any of those glutens. (Gluten sources like China apparently don’t care if they poison your dog, cat, your infant or you for that matter.) Wolf King is made by a company out where I live in El Cajon, CA called “Solid Gold” and it is sold around here. It is very pricey aka expensive but worth it to me. Yeah they use alpha tocopherol as a preservative…. Vitamin E by any other name…

    As for the naturals, even tocopherols can be toxic in large amounts so natural isn’t necessarily better. They are fat soluable and most of the fat soluables can be toxic because your body will store them in fats. Water soluables tend to go the way of the urinal if your body doesn’t use them right away. That is why you need water soluable vitamins often but the fat soluables can be stored in your body a lot longer.

  • Nicole Hornberger

    Hi Mike,
    I live in Panama City, Panama, and there is a rather limited supply of brands available here. Thanks to your site I have been able to identify one brand (four star) that IS available, though not always. When it’s not, I have to buy other brands, and go with one of the three star foods I can find here.
    I just want to say thank you for this web site. I have sent the link to all my serious dog lover friends.
    Nicole

  • Sally

    Sally, I went to get the Bil Jac treats last night and I think they are not good to use. Not only is the preservative BHA in it, it also has chicken by-product meal. Chicken by -products could include eyeballs, feathers or worse. Cheaper brands are made with lower quality “by-products which are zapped with high heat which destroys the nutrients, then it is sprayed with grease so your dog will eat it. The preservative, BHA in the treats are bad, can cause thyroid cancer. Here is an article on it.

  • http://DogFoodAdvisor.com Mike Sagman

    Hi Kim… thanks for your interesting comment and sharing the way you investigate dog foods. Initially, I was faced with those same concerns. Although this is an important factor in rating foods, I’m concerned with the sources of the individual ingredients and raw materials used to make these products.

    To the best of my knowledge, there are no laws requiring manufacturers to provide this information. Even our own “people food” contains (hidden) imported ingredients… critical information almost never clearly disclosed on the labels.

    But these days, that’s the way the food industry works… and much to our benefit. When I was a kid, strawberries were only available here in Virginia in the middle of the summer. Now, we get strawberries virtually all year long. It’s always summer somewhere. This past winter most of the fruits and vegetables we purchased came came from South America (Chile, Argentina, etc.).

    Just because a particular dog food is made “in house” is no guarantee that the ingredients used to make it are safe. You’re correct in saying that many dog food companies subcontract or outsource their manufacturing. And that’s the real problem… when something goes terribly wrong (like it did with melamine scandal of 2007), it affects lots of products… all at the same time. A catastrophe of major proportions.

    Outsourcing is a part of almost all industries… especially the pet food industry. If you avoid all outsourced dog foods you eliminate many of the finer quality choices.

    Thanks for your detailed contribution to our website. Because of your excellent points, I hope to address this issue in a feature article in the future.

  • wishaven animal rehabilitation

    During the 2007 Recall, I became a serious detective when it came to selecting commercial food (to use on occasion to supplement a home-prepared diet) for the critically or terminally ill animals who come into our rescue/rehab’s care.

    Nearly every food I fed, or had fed, was on the recall list! I ONLY purchased premium foods (Solid Gold, Wellness Core, Evo…) and was shocked to find that they were produced by “parent companies” (Menu Foods, etc.) who produced, on the same lines, poor quality grocery store brands.

    Besides learning to carefully look for the “red flag” items listed here, I started eliminating all foods that had these two little words on the label: “PRODUCED FOR:” or “DISTRIBUTED BY:” ! 99% of the time the manufacturer was not identified! Scary! So off to research again, often to find that the product came from a company involved in one of the recalls.

    I have found very few foods that are made “in-house,” without “out-sourced” ingredients. I am now RARELY feeding any kibble. At present, when I need something in an emergency/large intake situation (e.g., hoarder/puppy mill bust) I am feeding Fromm Family Four Star recipes. I’ve experienced/heard/read no negative feedback with it, and the dogs like it. The only concern I have is that it is very soluble.

    I have not visited this site in quite a while, but very much appreciate the valuable information available here.

    Thanks!

    Kim Lea, Founder
    Wishaven Animal Rehabilitation
    High Point, NC

  • http://DogFoodAdvisor.com Mike Sagman

    Hi Dave… The whole point of my article is to let my readers know that alpha tocopherol (a vitamin E derivative) and ascorbic acid (vitamin C) are both considered safe. My article states… ” What you mainly need to know here is that natural additives are usually considered very safe.” They are certainly NOT dangerous.

  • David

    a-tocopherol… vitamin E
    ascorbate… vitamin c
    sounds dangerous

  • http://DogFoodAdvisor.com Mike Sagman

    Hi Janet… Thanks to your suggestion, I’m adding Exclusive Dog Food to my “To Do” list. Look for the review here on this website in the near future. Thanks for taking the time to write.

  • Janet Saunders

    Mike,

    Hello! I am a friend of Claudia’s. I have one of her chocolate labs Doc Riley. I am a breeder and I want to make sure that I am feeding my dogs and puppies the best possible diet. We are currently feeding them Exclusive. I would love for you to check out the ingredients and see what you think.

    Thank You,
    Janet Saunders
    http://www.LaKobielabs.com

  • http://DogFoodAdvisor.com Mike Sagman

    Hi Brenda… Haven’t yet reviewed Beef ‘n More. But thanks to your suggestion, I’m adding it to my “to do” list.

  • Brenda

    Is Beef n’ more a good dog food brand?

  • David

    wow i kinda had an idea of this… but this is too much ! my cat never liked wet cat food… maybe he was smart :)