What is never specified are the additives that go into the typical can of dog or cat food. Companies are so liberal with additives-and regulators so lax about what goes into pet food-that with each devised improvement in shape, texture or form, more chemicals are added.
Besides preservatives, pet foods can contain up to 27 different types of additives-from flavour enhancers, and anticaking, colouring, curing and drying agents, to emulsifiers, sweeteners, solvents, stabilizers, thickeners and texturizers.
If your dog is medium-sized and subsists on pet food, he could be eating as much as 10 lb of preservatives every year.
Here are the main culprits in most standard commercial pet food.
- Propylene glycol, a humectant in semi-moist and dry foods, is molecularly similar to antifreeze and hydraulic fluids. This agent has been proven to be a major contributor to feline cardiac disease, according to research accepted by the US Food and Drug Administration (FDA). A 1994 FDA report noted ". . . recent reports of scientifically sound studies show that propylene glycol reduces red blood cell survival time, renders red blood cells more susceptible to oxidative damage, and has other adverse effects in cats consuming the substance at levels found in semi-moist food" (www.fda.gov/ AnimalVeterinary/ResourcesforYou/UCM047113). In January 2001, the FDA's Center for Veterinary Medicine (CVM) banned the use of propylene glycol in semi-moist cat food after it was shown to cause Heinz body formation (small clumps of denatured haemoglobin) in red blood cells (Vet Pathol, 1990; 27: 299-310). However, to our knowledge at this time, this chemical can still be used in dog food in the US. In the European Union, propylene glycol hasn't been approved for use as a food additive.
- Butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) are preservatives that prevent fats and oils from going off. BHA and BHT have both been shown to affect the nervous system of animals, particularly the neurological development in young animals, and may also cause cancer (Food Chem Toxicol, 1986; 24: 1071-82; J Am Oil Chem Soc, 1972, 52: 59-63). Many companies list these as "EU permitted antioxidants" without identifying them. In addition to these agents, product contents such as fish or meat may require further preservatives at some point in the manufacturing process. Although BHT is banned in many places, it is still permitted in the US. However, natural preservatives such as vitamin E and ascorbic acid (vitamin C) can do the job just as well, and a number of 'natural' pet-food manufac-turers are now using these instead.
- Ethoxyquin, a preservative originally developed by Monsanto to stabilize rubber, is also used as an insecticide and pesticide, and is required by the US Coast Guard to be used as a preservative in fish meal.
One study commissioned by Monsanto found evidence of liver pigmentation changes and elevated liver enzymes, depending on the dosage of the preservative, in dogs, but was so riddled with unprofessional documentation that the FDA demanded a second study, completed in 1996, which found no such evidence. It has never been tested for safety in cats.
As a precautionary gesture, in 1997, the FDA's CVM requested that the maximum level of ethoxyquin in complete dog foods be voluntarily lowered to 75 parts per million (ppm) (www.fda.gov/Animal Veterinary/ResourcesforYou/ UCM047113).
Although ethoxyquin is allowed for human consumption at levels of 100 ppm, this is only in spices such as cayenne and chilli powder, where the actual amounts consumed are small, compared with a dog or cat consuming processed pet food day after day, which will accumulate into enormous amounts in its system.
Furthermore, although US law supposedly requires any preservatives such as ethoxyquin to be disclosed on the label, pet-food manufacturers blithely disregard this.
- Propyl gallate, a derivative of natural gallic acid made by hydrolyzing tannins from tara (Caesalpinia spinosa) fruit pods, is a common antioxidant used to preserve cosmetics. It is suspected of causing cancer and liver disease, claims that nevertheless have not been definitively proven (Free Radic Biol Med, 2004; 37: 287-303).
- FD&C Red No. 40 (E129). Some of the moist or canned foods made to approx-imate "juicy red beef" are loaded with red dye, and have been known to stain and discolour a dog's hair. You can test this by taking some reddish-coloured wet or dry food, wetting it further and placing it on an absorbent paper towel. If the food stains the paper, it's likely to eventually show up in your pet's light-coloured or white hair. The most commonly used food dye, it underwent mouse studies that were confirmed by the FDA as being flawed (www.fda.gov/downloads/AdvisoryCommittees/CommitteesMeetingMaterials/FoodAdvisoryCommittee/UCM255119.pdf).
- FD&C Blue No. 2 (E132). This indigo dye, produced by a chemical made from formal-dehyde and aniline, is the main blue in blue jeans. It underwent animal testing that suggested that it caused brain tumours in male mice. Nevertheless, the FDA pronounced that there was "reasonable certainty of no harm" (www.epa.gov/opprd001/inerts/foodcolors.pdf).
- FD&C Yellow No. 6, or tartrazine (E102), is a chemical compound of sulphuric acid and sodium nitrite, and the third most common colour additive. Studies of this yellow dye, even though industry-sponsored, showed evidence that it causes tumours of the kidney and adrenal glands, and that the dye is contaminated by several carcinogens. Although the FDA concluded that Yellow No. 6 doesn't pose a cancer risk to humans, it is known to cause allergic reactions (www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=201.20). The high level of processing and the laxity of regulations is nothing less than scandalous, threatening the lives of millions of companion animals with sub-standard food and potentially dangerous cocktails of additives. By feeding your pet standard dog or cat food, you are literally taking their lives in your hands.
Factfile: Natural alternatives to pet food
- Make your own pet food.
- For dogs. Cooked: This should be 60-per-cent lightly steamed, shredded or ground lamb, beef, venison, rabbit, ostrich or turkey. Pork, fish or chicken are considered 'weak' meats for dogs. It can also include 30-per-cent cooked grains (oats, barley, millet or spelt) and 10-per-cent raw or lightly cooked vegetables or fruit. Raw: A variety of meats and meaty bones should make up approximately 70 per cent of the diet, plus 10 per cent made up of organ meats, and 20 per cent of a variety of raw pureed vegetables, nuts, seeds and sprouts.
- For cats. Raw: These 'obligate carnivores' need mostly meat, including a combination of muscle and organs. Some 300 g/day of meat will provide enough protein for an adult cat. If poultry is used, include the skin for its fat content. Cooked: As cooking destroys taurine, which is essential for cats, be sure to supplement with good-quality supplements that are specifically made for cats.
2. Buy only wholefood pet food.
- Study the labels. Be wary of pet foods that purport to be 'natural', but which, in fact, contain the same byproducts and meat derivatives as most commercial brands. Look for terms like "natural human-grade pet foods", and ensure that there's at least 60-per-cent meat and only wholegrains such as rice.
- Cats need mostly meat, so avoid products with wheat. Buy brands that use natural preservatives, such as vitamin C, vitamin E, strong oils of rosemary and/or spices such as clove.
WDDTY Vol. 22, 12. March 2012