The popularity of dry pet foods has grown considerably over the last few years. The main reasons for this has been convenience, ease of use and less waste compared to tinned products. In addition, a great many dogs and cats that cannot tolerate tinned foods are able to digest dry foods without any problems. Consequently, the variety of dry products has also increased, with specific foods now related to lifestyle, life stages and to health issues.
Tinned pet foods are preserved by cooking and then protected by the metal can from contaminants such as bacteria. In contrast, dry foods have a very low moisture content and are generally resistant to the effects of bacteria and fungi. They can, therefore, be packaged in sacks, which is much more convenient.
Unfortunately, the fats in dry pet foods must be protected from becoming oxidised and going rancid. A large number of manufacturers will use chemical preservatives to do this, although fats can be preserved adequately by natural means. Some manufacturers will also add colouring and flavouring agents, which are added purely for cosmetic reasons.
There is growing concern over the long-term use of additives in pet foods, particularly anti-oxidants (used as preservatives) and, to a lesser extent, colourings and flavourings.
The most frequently used chemical anti-oxidants include:
Most concern has been expressed over Ethoxyquin in recent years. It is used because it has superior anti-oxidant properties, high stability and is reputed to be safe. However, its toxicity rating is classed as 3 or “moderately toxic” (in a range of 1-6)¹ and is readily absorbed into the body and then excreted in the urine and faeces, with residual amounts left in the liver and fatty tissues.
Reports from the United States suggest that Ethoxyquin might be related to a number of health problems in dogs². These include liver cancer, skin allergies, autoimmune disease, thyroid problems and reproductive and birth problems.
Studies by the Federal Drugs Administration (FDA) in the States have shown that when levels of Ethoxyquin are greater than 75 parts per million (ppm), changes in the liver can occur as well as the development of spots on the liver³.
As a result of investigations carried out on the possible effects of Ethoxyquin, the levels in dog food have been reduced.
It appears that pure-bred dogs may be most susceptible to the effects of chemical anti-oxidants fed daily over long periods of time. The smaller breeds are at most risk, as they ingest proportionally more preservative in relation to their body size. Suspicions are hard to prove, but many would claim that the increasing incidence of chronic ill-health in dogs over the last 15 years or so is largely due to the addition of chemicals to processed pet foods. It would be reasonable to assume that the same may well be true of cats.
Understanding the need for healthy, additive-free dry foods, Denes produce the following recipes, which also have the benefit of added herbs:
Other Denes fact sheets to read:
¹ Gosein RE Smith RP and Hodge HE (1984), Clinical toxicology of Commercial Products 5th ed, pp 2 406, Baltimore Williams and Watkins
² Pitcairn, RH (1995), Natural Health for Dogs & Cats, pp17-21, Rodale Press, Inc.
³ Johnson, RA, (1998), Controversies in Pet Nutrition. Petfood Forum Proceedings, 1998.