Why Switch Foods? (Part 1 & II)

The spice of life is variety, or so they say. If that’s true for people, what about our dogs and cats?

Pet food company advertising would have you believe that feeding one food (theirs!) for your pet’s entire adult life is the way to go. But that concept is all wrong. When you really think about it, it doesn’t even make sense!

For many of us, our pets are our children. So let’s imagine for a moment that you have a child, let’s say a 2-year old boy named Junior (of course!), and let’s imagine taking him to the pediatrician for a check-up. The doctor bustles in, looks Junior over, then plunks a big bag of Yummi-o’s down on the exam table.

“Good news,” he beams. “All the vitamins, minerals and a perfect balance of nutrients that Junior needs are right here in New Complete Yummi-o’s. Now all you have to do is make sure Junior gets three servings every day.” The doctor wags his finger at you as he continues in a serious voice, “Now, since this food is perfectly complete and balanced, you mustn’t feed Junior anything else—no apples or oatmeal or broccoli or peanut-butter-and-jelly sandwiches—because you might cause a nutrient imbalance!”

Well, this sounds a little weird, but you trust the pediatrician—after all, it’s his name you see on all the gold-embossed university degrees on the exam room wall—so you go ahead and put Junior on an all-Yummi-o’s diet.

Time passes, Junior grows, and by golly, it sure is cheap, easy and convenient to feed him. The next year you bring him in for his checkup, and the doctor is very pleased.

“He looks great,” says the doc. “I see you’ve been keeping him on Yummi-o’s. Terrific! Now, I have more good news for you! Yummi-o’s now comes in Life Stages! You’ll keep him on Yummi-o’s Growth until he starts kindergarten. Then he’ll go on Elementary Yummi-o’s until he hits middle school. Then you give him Adolescent Yummi-o’s until he’s 18, when he can be weaned onto the Adult formula. And it gets even better—you can eat it too! New Improved Yummi-o’s is complete and balanced for adults up to 65 years old.”

Ridiculous? Of course! What rational parent would feed a child only one food for years on end? Even if the food were, in fact, complete and balanced, most of us would consider it unnatural, even cruel to the child. Never give Junior a carrot or a glass of orange juice? No fresh food at all? Preposterous!

Then why does everyone think it’s okay to feed a cat or dog that way?

We would think a pediatrician who recommended a single food diet for a child was bonkers, yet when the veterinarian recommends a single food for our pampered pet, we obey without question. But feeding a dog or cat is not all that different from feeding a child.

It’s way past time to bring a little common sense to bear, and common sense dictates that an animal ought to get a variety of foods.

The veterinary literature is full of cases where nutritional deficiencies (or excesses) were discovered, and in virtually every one, the problem arose (or was discovered) because the animal was kept on one food for a long period of time.

Cats, being strict obligate carnivores, have most often been the unintended victims—taurine, copper, vitamin E and potassium deficiencies have turned up in cats fed certain foods (which were, by the way, “complete and balanced” according to the standards at the time) as their sole diet.

Dogs, whose omnivorous metabolism is more adaptable, haven’t had quite as many problems, though zinc and fatty acid deficiencies have occurred on certain poor quality foods.

The Myth of Complete and Balanced

Wait a minute … aren’t we indeed talking about “complete and balanced” foods? How can a complete and balanced food have deficiencies or excesses of nutrients? Unfortunately, even for the best commercial pet foods, there are several places along the road to the retail store shelf where any food’s nutritional value can go astray.

1. The standards by which the food is made aren’t perfect. Pet nutrition is an evolving science, and we don’t yet know all there is to know about it (if we ever will!). Veterinarians have seen many examples of how the particular nutritional needs of a species become known—mainly by stumbling on cases where they aren’t being met.

2. The exact quantities of individual nutrients in a given ingredient may not be known, or may be inaccurately assessed. A shipment of barley might be presumed to have a certain nutritional composition based on analyses of previous batches, but depending on the weather where it was grown, the soil conditions, and the type of fertilizer used, the exact amounts of each nutrient may vary. The same applies to animal-based ingredients.

3. Ingredient quality may be inconsistent or unknown. A vitamin-mineral premix purchased from an outside supplier and added to the food may guarantee minimum levels of each item, but if the quality control on that product was poor, the finished pet food will merely compound the error. Many vitamins and minerals are normally “overdosed” in pet food to make up for loss of those nutrients during processing, transport and storage. Some of these may present a health risk. For instance, iodine excess in cat foods is suspected of contributing to the skyrocketing incidence of hyperthyroidism in older cats; and a zinc overdose in a commercial dog food sickened author Ann Martin’s dogs and started her on a quest through the maze of pet food manufacturing and regulation, detailed in her stunning book Food Pets Die For in 1997.

4. Processing alters many nutrients. The heat used in various stages of pet food manufacturing can alter many ingredients, some for the better and some for worse. Carbohydrates are made much more digestible by cooking, but proteins can be denatured, vitamins can be destroyed, and fats can be damaged by heat. In general, pet food manufacturers are aware of changes that occur in their products during processing, and compensate for heat-sensitive ingredients by adding supplements, such as extra vitamins, but alterations in proteins and fats are not generally accounted for.

5. The pet food manufacturer itself can make mistakes. It’s obvious from feed reports from around the country that virtually every manufacturer—no matter how good, bad or indifferent its reputation—at one time or another fails one or more tests for protein, calcium, magnesium or other nutrients.

6. Increased risk of toxic effects. As many people unfortunately discovered in last year’s recalls, feeding the same food, from the same manufacturer, who continually buys from the same suppliers, can lead to health problems for your animal companion. While some of the recalled foods had such huge amounts of melamine that even one serving was deadly, feeding a variety of foods could have “diluted” the effect of the toxin and caused less harm for thousands of pets.

Next time, we’ll talk about how periodically switching foods can prevent food allergies and finicky eating behavior.

Why Switch Food Part II…

In this post, we’ll continue our discussion about the reasons for periodically switching your pet’s food.

Let’s consider all the different kinds of pet food on the market. When I started veterinary school, there were basically two kinds of pet food: adult, and puppy or kitten (growth/lactation); “light” foods were just coming into the market, although there were no rules at the time about calories or fat content, so the claim was a little questionable.

But looking at dog food today, we find all-life-stages food, baby dog food, puppy food, adult food, mature food, aging food, senior food, food for sensitive stomachs, food for itchy skin, food for small, medium, large, and giant breed dogs, food for Yorkies and Dachshunds and Poodles and Bulldogs and Shih Tzus and Boxers and Retrievers, vegetarian food, high performance food, reduced calorie food, light food, and an array of veterinary diets for dogs with heart disease, kidney disease, liver disease, arthritis, digestive problems, cancer, diabetes, bladder stones, dandruff, and dirty teeth.

Cats, being more or less the same general size and shape, have been spared some of this, but recently a spate of new foods for indoor, outdoor, and specific breeds of cats has arrived on the market. And there are designer diets for hairball hurlers, happy bladders, and tartared teeth. And, of course, most of the veterinary diets available for dogs have a feline counterpart.

However, the standards for pet food nutrient levels remain the same today as they were when they were set in 1989 (for dogs) and 1991 (for cats). There is one chart for adult maintenance, and one chart for growth/lactation. (Food intended to treat disease must provide documentation to FDA that it actually works as advertised, but the research is done by the company making the food-–and the claim.) New standards for dog and cat nutrition were just recently published by the National Research Council, but it will likely take several years before they are reviewed and accepted by AAFCO. Until that happens, pet food manufacturers don’t have to abide by them.

Is There Really a Difference?

Is it just me, or is something wrong with this picture? How much different are these foods really from each other—given that they all have to meet the same nutritional standards? For instance, if you look at the ingredient statements on the labels of regular versus large breed foods, they look pretty similar. In any case, the exact nutritional requirements of hundreds of breeds (and infinite combinations of breeds), every imaginable lifestyle, and each animal’s individual metabolism simply cannot be accurately known, at least not with current technology.

Moreover, even an individual animal’s needs fluctuate, depending on the season, activity level, normal variations in hormone levels and organ functions, infections, parasites like fleas, illness, and a host of other factors. A dog who spends a lot of time outdoors in Colorado may need a higher calorie/higher fat food in the winter to cope with the cold, but unless she is extremely active in warmer weather, such a food may put on the pounds if fed year-round. It does make sense to try to match the food to your animal’s particular needs as those needs vary, although whether you can really do this based solely on a manufacturer’s claims for its food is unlikely.

The Allergy Factor

Another pitfall of feeding a single food is the potential for your animal to develop an intolerance or allergy to one or more ingredients. A dietary intolerance is a reaction to something in the food, rather than the food itself.

The list of suspects is a long one and includes flavoring agents, coloring agents, emulsifiers, humectants, stabilizers, thickeners, texturizers, and dozens more. Different manufacturers use different additives, so changing foods periodically may avoid constant exposure to certain ingredients that could become a problem for your animal.

True food allergies are thought to be uncommon (though more common in cats than dogs), but many practitioners and veterinary nutritionists are coming to the conclusion that most, if not all, cases of inflammatory bowel disease are linked to food.

It usually takes months to years of exposure to a food to develop an allergy. Allergies are usually to proteins, which are found in animal products, of course, but also in to some extent in the cereal grains commonly used in pet food. Corn meal (also known as ground yellow corn) contains 9 percent protein, soybean flour contains 37 percent protein, and wheat contains 10 percent protein. Corn and wheat are very common allergens in pets.

Switching foods every three or four months, from chicken-and-corn, to lamb-and-rice or turkey-and-barley or duck-and-green peas or rattlesnake-and-quinoa may help prevent your animal companion from becoming food-allergic in the first place. (But remember to carefully check the ingredient list on the package-–a food legitimately labeled “emu-and-amaranth” could actually consist mainly of corn and chicken.)

A Matter of Taste

The last big reason to change foods periodically is to prevent finicky eating habits and enable the gut to handle challenges without catastrophic consequences.

Pet food makers are masters at making the food irresistibly tasty. Consequently, an animal fed a single food may become “addicted” to it. I once got a call from a woman whose cat would not only eat just one flavor of cat food, but it had to have been canned at a particular factory! Cans of the same flavor with a different code stamp were rejected by the cat. She was frantically searching from coast to coast to find more cans from that factory—which had since closed down.

Some foods are produced on a “least cost” basis, and the ingredients may change significantly from batch to batch. “Fixed formula” foods always use the same ingredients. Depending on ingredient quality, such a food may be a better pick. But even fixed formula foods that use the same ingredients all the time may still periodically alter certain characteristics, such as size of the kibble, or flavoring components.

When you buy a new bag of the same food, it could be just different enough from the usual fare that your furry friend will turn up her nose at it. Or you might run out of her favorite food and not be able to get over to the gourmet pet store right away—she’ll just have to eat something from the grocery store for a few days. If you board her, she may get fed whatever the kennel is using (errors can be made, even if you supply your own food).

It’s best to have your animal companion develop more “cosmopolitan” tastes, and be willing to eat whatever you give her. (For some dogs in some situations, training to accept food only from you can and should be done, but that’s an issue beyond the scope of this blog.)

Next time, we’ll get to the nuts and bolts of how to make the switch. The first word of caution: too radical or too abrupt a switch could cause your pet stress and tummy upset. On the bright side, it could keep your local carpet cleaning company busy!

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3 Responses so far »

  1. 1

    This is a Great article~

    I am going to put a link it with a small blurb, on my forum and hope everyone
    reads it ;)

    It would be great if you has an RSS feed so I could just list that on my own
    blog and in my forum :)

  2. 2

    Molly said,

    YAY! Finally an article where my little doggie is understood. As a puppy (he still is) he faithfully ate his “one” food recommended by the vet. At about 6 months of age (after tasting little “tidbits” of human food) he just stopped eating it. He looked at this bowl of flavorless stuff and looked at me, and I could tell we were in for a fight. Now he’s 8 months of age and we’re still experimenting. I bought a book on “natural – human” food diets for dogs, have added vita-powder to human meat that I cooled myself (beef, chicken!), and honestly, I feed him more nutritious human food than I eat myself! He loves the variety, different presentations of foods, and even eating at different times of day. I have 6 bags (6!!!) of the best dry dog food money can buy (this is top quality stuff), and he won’t touch any of it! I also have sampled a variety of canned dog foods and he’ll only eat very small quantities. I won’t say his “eating issues” are completely over, but the frustration of watching him sit by a full bowl of food, not eating, is over for me.

  3. 3

    J Hofve, DVM said,

    There’s an old saying, “You get what you pay for.” This applies to Kirkland and similar foods, who have some very clever marketing and advertising staff, as well as the buying power of a large company.

    It’s been bothering me that many ingredient lists on dog food are looking so similar to the truly superior brands, and I finally figured out why. Take an ingredient like “chicken meal.” This comes in several grades, as well as being available from overseas markets in China, Africa, etc. The ingredients going in to Kirkland pet food are the cheapest they can possibly get and still retain the technical label of “chicken meal.” A switch to much lower quality ingredients is what happened when Procter & Gamble bought Iams, and what suspect will eventually happen with P&G’s recent purchase of Natura.

    BTW, Diamond is certainly not known as a *good* quality manufacturer. In fact, its reputation is for cheap knock-offs of more expensive, better quality food. Because they make food for Walmart, Costco, etc. they have tremendous buying power. Nevertheless, there just aren’t enough *good* quality ingredients to support that size of market. If they’re selling a dog food for $1.50 per pound, after you pay for packaging, advertising, shipping, distribution, and retail shelf space, the cost of the ingredients comes down to about 29 cents a pound. What kind of quality do you think you can get for that? ;-)

    I looked at your website, and couldn’t find any info on the actual ingredients, other than a few blurbs promoting particular items. What’s up with that?

    Cheers,
    Dr. Jean


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