The Dog Cancer Survival Guide (26 page)

Regulatory agencies, like the Environmental Protection Agency in the U.S., conduct safety studies for known carcinogens, which help the agencies decide what a “safe” level of exposure is for each agent.

The problem is that most safety trials look at each carcinogen in a vacuum, while most of us – and probably your dog, too – live in the real world. Out here, in the real world, we almost never encounter one substance at a time. We may be drinking, eating, or inhaling one agent, while other chemicals are consumed or already present in the body. This combination of carcinogens can create synergy (when two or more agents working together have amplified effects, beyond what each would cause alone).

One example of synergy features two familiar non-carcinogens, prednisone and aspirin. If your dog had arthritis, you might think it’s a good idea to give him a dose of the anti-inflammatory, prednisone, along with aspirin for pain relief. Both of these drugs are generally safe to use, but the synergistic effect of the two together puts your dog at a much higher risk of vomiting, diarrhea, digestive tract inflammation, stomach or intestinal bleeding, and intestinal ulceration (holes).

It is impossible to construct a safety study for any agent that accounts for every single combination of substances. As you’ll see when you read about nitrites and nitrates, even harmless substances can be converted to carcinogens when they’re combined in the right circumstances. It’s also impossible to test all of these combinations over time. Real life exposure to carcinogens may last years, but most safety studies take place over a much shorter time. Because of this, the long-term effects of carcinogen exposure are largely unknown.

The bottom line is that safety studies cannot accurately predict all the cancer-causing effects of carcinogens. It is possible to nail down what is
definitely
carcinogenic, but not possible to say what
could
be carcinogenic. This is why it is important to limit carcinogen exposure when you can, and counteract its negative effects whenever possible.

Commercial dog food is convenient and relatively inexpensive, but most of it – including some “scientifically-formulated” and “premium” brands – is not particularly good for your dog. I want to be clear that I am not condemning every commercial dog food, but I do think you should watch out for commercial foods that have been processed at high temperatures, or those with nitrites and nitrates or ethoxyquin.

You have probably heard of
nitrites and nitrates,
the food preservatives found in many processed meats and some brands of dog food. Although these preservatives do a great job of extending food’s lifespan on the shelf, they can be harmful once they’re in the body. According to studies conducted in rats, dogs and people, nitrates and nitrites can combine with naturally occurring amines (which mainly come from protein in the diet) in the stomach to form Nnitroso compounds, known carcinogens. This is a good example of synergy.

Because of the potential for synergistic carcinogen formation, I do not recommend feeding your dog food that contains nitrites or nitrates. This includes some commercial dog foods, but also many human foods, such as hot dogs. Dog snacks with meat flavoring may have these chemicals as well; check the ingredients on the product label.

Ethoxyquin
is a preservative that may be in some commercial dog foods. It has been shown to increase the effects of some carcinogens in rodent studies, and to cause kidney damage and pre-cancerous changes in the kidneys in humans when given in high doses. It does not seem to be carcinogenic by itself at the levels found in dog foods, but I am concerned about the possibly synergistic effects for dogs with cancer (see the synergy discussion on
page 73
).

You might not find this preservative listed on the label of your dog’s food, but you might see “fishmeal;” federal law mandates ethoxyquin is packed along with fishmeal for shipping. For this reason, I recommend avoiding any food made with fishmeal.

To make most dry dog foods, a mixture of meat or fish, fat, grains (and in some cases, animal remains) is heated to an
extremely high temperature
(sometimes as high as 392°F) after being pushed through a machine called an extruder (which creates the uniformly shaped kibble). Many dog treats are also made this way.

The high temperatures produce chemicals called
heterocyclic amines
, which are known to be extremely potent carcinogens. If the food is starchy, like the corn found in many commercial dog foods,
acrylamide
may also be created, particularly when the starch is cooked with oils. Acrylamide, a potent carcinogen that can be found in many processed food items (french fries and potato chips, for example), has recently become the subject of intense study. While results for non-lab animal species have not yet yielded a consensus, acrylamide has been proven carcinogenic in lab animals.

Both heterocyclic amines and acrylamide likely remain in the kibble, even after it cools off, as they do with human foods. Neither compound has to be listed on the manufacturer’s product label; they are not present before the mixture is processed, so they are not considered ingredients by regulatory agencies.

Whether they are listed on the label or not, the high-heat processing of many dry dog foods and treats probably creates carcinogens. In
Chapter 14
, I will recommend a home-cooked diet, prepared at relatively low temperatures, to avoid creating acrylamide and heterocyclic amines.

(Cooking at or below 212° Fahrenheit avoids both acrylamide and heterocyclic amine formation, and cooking below 302° Fahrenheit avoids heterocyclic amine formation.)

All kibble is cooked at high temperatures, and I suspect that other, non-kibble commercial dog foods are, too. Second only to a home-cooked diet, I recommend doing the best you can with high quality brands such as Halo, Solid Gold, Orijen, Blue Buffalo and Taste of the Wild. Dehydrated brands are also a good idea (Honest Kitchen, for example), because they do not heat the food at all, and you use warm water to reconstitute it at home. You might also consider partially cooked or frozen brands.

Human cancer rates have increased by 27% since 1950, and that number does not even include cancers caused by cigarette smoking. Some cancer researchers have noted that disease rates rose as modern life conveniences increased (for example, processed foods and electronics).

This is interesting, because there are places in the world – we often call them undeveloped countries – which enjoy a much lower rate of cancer than we do. Studies show that when people migrate from these countries to more developed countries, their cancer rates rise to match the rates in their new home. Could cancer, which is sometimes called a “disease of civilization,” have a direct relationship to life style choices and diet?

You bet it could. One study shows that 85% of human cancers are a direct result of diet and lifestyle choices, and that roughly 30% of cancers can be avoided by improving diet alone. Because of our physiological similarities (remember, many human cancer studies use dogs as test subjects), if this is true for us, it may also true for our dogs.

Taking steps to reduce the impact of civilization on your dog’s body is an important part of Full Spectrum cancer care. Changing your dog’s diet and other specific recommendations for accomplishing this are included in the next section of this book.

In 2008, investigative reporters from the Associated Press (AP) published a series of articles about our drinking water. They found that at least 46 million people in two dozen major metropolitan areas are drinking water that contains minute amounts of pharmaceuticals, including still-active hormones from birth control pills, chemotherapy agents, and antidepressants.

How did these drugs get into our water supply? One way is through the sewage system. If an individual takes a pill – let’s say a heart medication – and the body does not completely absorb it, the excess is released through the bowels and the urinary tract. Sometimes, breakdown products (metabolites) that still have activity are released, also. These flow into the sewage system, where the water is treated to make it drinkable, then piped back into household faucets for normal use.

Water treatment facilities can remove bacteria and protozoa, but, according to the water suppliers
interviewed for the AP series, the technology to remove pharmaceuticals is not in place and/ or is not definitively working. Therefore, the drugs and active metabolites may remain, even in the treated water.

According to the AP, this inadvertent dumping of prescription drugs is not the only problem. Some hospitals across America dispose of unused medications by flushing them down the toilet! In these cases, the drugs enter the sewage system at full strength. Our dogs ingest these small doses of pharmaceuticals in their water, over the years. A medical doctor would never recommend taking random pharmaceuticals all mixed together, and neither would a veterinarian. The synergistic results are unpredictable and could, at least theoretically, set the stage for cancer development in some dogs.

The federal regulation of prescription drugs in drinking water is complex. For example, pharmaceutical waste from private homes is not currently regulated. Some drugs are classified as medical waste, not hazardous waste, which makes them subject to different regulations. According to the AP investigation, the EPA acknowledges the problem, and some water suppliers are working on it. I have a suspicion that we will be hearing more about this as time goes on, because it’s too big a potential danger to ignore for long.

Lacking direct control over our water supply, I recommend giving your dog water that has been purified through filtration or reverse osmosis. To be sure you are removing as many unwanted pharmaceuticals compounds as possible you will likely need to use an ozonation system; water filtration technology is always changing and improving, so as this danger becomes more known, systems will likely improve and become less expensive.