Pet food is made from what giant, multinational agribusiness considers “byproducts” of human food production - stuff that is mostly unfit for human consumption. Much of it would become costly garbage if industry could not legally make it into dog and cat food. Basically, you would never feed it to your pet if you knew what was in it. Pet food agribusiness is a $30 billion a year mega-industry in the US, and it is growing every year.
The delightful industry term for animal byproducts is “offal” - carcass parts that cannot be used for human food, which are automatically slated for animal food production at the slaughterhouse. “Offal” has been estimated to amount to approximately 40 billion pounds per year in the US, and often contains significant amounts of rancid rendered fats, oils and grease. It also includes bacterial- or parasite-contaminated carcass parts which could not pass human food inspection. This is especially true because offal contains animal intestines and their contents, which are rich in e-coli. Next time you scrutinize the stuff in a can of cat or dog food… think “offal”.
At first the contaminated pet food showed up mostly in the US, but eventually surfaced in other places, such as South Africa
and Puerto Rico
However, there is a slight problem with the melamine hypothesis. The affected pets are thought to have died from kidney failure, but melamine is not known to cause kidney failure. The amount of melamine required to cause death is very large, far beyond the amount found in contaminated pet foods. The main health issues associated with chronic melamine exposure include cancer and reproductive damage. Indeed, there is no data that suggests that melamine even in significant doses can cause acute adverse effects such as kidney failure and death. The levels of melamine found in the pet food were far below those considered acutely toxic.
So what caused the animal sickness and death, and where did it come from? Some investigators have noted that ethylene glycol, the main ingredient in anti-freeze, does cause acute kidney failure in animals. Many pets die every year from drinking anti-freeze drained out of car radiators because it has a sweet smell and taste. However, it does not seem likely that sufficient levels of ethylene glycol could get into pet foods.