The basic ingredients that you want to look for are:
-Protein from a meat, fish, or poultry source
-Taurine, an essential amino acid
-Certain other vitamins, minerals, enzymes, and fatty acids
As a general rule, the order of ingredients is just as important as the kind of ingredients. Unless a cat is on a special diet for a medical reason, the protein source will always be listed first, followed by other ingredients listed in the order of their percentage to total weight. Here are some quick guidelines (after the protein source, the order may vary from product to product.:
- Named Protein Source
This is by far the most important ingredient to look for in cat foods: a specific protein source other than "meat." Look for chicken, turkey, lamb, salmon, etc. (May be followed by named organs, e.g. chicken liver, chicken heart, both rich sources of taurine.)
- Specific Carbohydrates aka "fillers"
Cats are obligate carnivores, i.e., they must have meat to survive, and they do not need carbohydrates. In fact, cats have problems digesting some carbohydrates, and many food allergies are triggered by the carbohydrate content of foods. However, most dry foods depend on carbohydrates as the "fillers" needed to hold the other ingredients together for dry cat food. Look for whole grains, such as brown rice, barley, or wheat (wheat may also trigger allergies in some cats).
- Named Fat Source
Look for a named fat source, such as "chicken fat." You may also see sunflower oil, or other oils listed, usually in premium foods.
- Vitamins and Minerals Vitamin C (calcium ascorbate) and/or Vitamin E (alpha tocopherol) are often added as preservatives, along with other vitamins and minerals.
Taurine is an amino acid that can be readily produced by the human body, however, cats need a dietary source of taurine for good health. In a 1974 study, it was found that a diet deficient in taurine contributed toward retinal degeneration in cats. Taurine deficiency can also cause a heart disease called dilated cardiomyopathy. For several decades cat food manufacturers have added taurine to cat food.
- BHT, BHA, and ethoxyquin
These are chemical preservatives which are very effective at preserving dry cat food, but are suspected to be potentially cancer-causing agents. In recent years, many pet food manufacturers have moved toward using more "natural" preservatives, such as Vitamins C and E.
- Meat By-Products
Meat by-products are the "non-rendered, clean parts, other than meat, derived from slaughtered mammals. It includes, but is not limited to, lungs, spleen, kidneys, brain, livers, blood, bone, partially defatted low-temperature fatty tissue and stomachs and intestines freed of their contents. It does not include hair, horns, teeth and hooves." Besides the fact that you don't know what species of animal the "meat" comes from, by-products as a rule are considered an inferior form of the protein which cats need.
- Meat Meal, Meat By-Product Meal
"Meal" is generally produced by rendering, a process which raises a red flag to cat enthusiasts. I would definitely recommend avoiding cat foods containing these ingredients.
- While dry food is convenient, and can be left out for "free feeding,"
- Canned food contains water, and many cats do not drink water regularly
- To ensure that your cat gets the right amount of nutrients. That "near-perfect" food you've selected might be adding too little (or too much) of certain minerals and/or vitamins.
- Cats may actually become bored with the same food day in and day out, and simply quit eating.
- To head off possible allergies to certain ingredients. Cats (like humans) develop allergies over a period of time. Although the incidence of food allergies in cats is rare, cat owners might want to err on the side of caution, particularly if their cats have shown evidence of allergies in the past.
To sum things up, when you are buying cat foods, look for:
- Named protein source - look for "chicken, lamb, or beef," rather than "meat."
- On canned food particularly, the protein source should be the first listed ingredient
- Check the expiration date for freshness
- Words such as "By-products," "meat and/or bone meal," "animal digest," most other descriptions including "digest" or "meal," and added sugars.
- Chemical preservatives, including BHA, BHT, ethoxyquin, and propyl gallate
- Corn meal as a filler
- Excess of carbohydrate "fillers" (Dry food can contain as much as 50 percent grain)
Information shared from the writings of Franny Syufy at About.com Guide