Item: In 1982, several veterinarians at the University of California-Davis Veterinary School began to notice an increasing number of dogs with unexplained skin lesions.

The animals, which were of different breeds and ages, had a common factor: All were being fed generic dry dog food. When they were switched to a national brand of dog food, "the animals felt better within 24 hours and the lesions cleared up within a week," claims Dr. Peter Ihrke, who is preparing a scientific paper on the topic for a veterinary journal.

Item: A recent survey conducted at the University of Georgia found that puppies fed so-called "price-brand" foods gained less weight, grew less and required more food to provide the same amount of nutrition as the control groups fed a national brand of food.

(Unlike generics, which usually are sold in plain white bags marked simply "dog food" or "cat food," price-brand foods may look similar on the shelves to their national competitors, but are generally distributed on a regional rather than a national basis with little if any advertising.)

Puppies fed one of the price-brand foods in the study experienced a change in coat color during the test, indicating some sort of nutritional deficiency, according to the researchers. At the conclusion of the 10-week test, the animals were fed a national brand of food and their coats returned to normal.

Item: A study conducted by Ralston-Purina found that 83 percent of the 78 different generic dog foods sampled failed to meet standards set by the National Research Council for the seven nutrients tested. Fifty-one percent of the samples failed to live up to the nutritional claims on their own labels.

Although these findings have not proved to be life-threatening to dogs and cats, what you're feeding your pet, it seems, may be hazardous to its health.

"Whenever I see an animal with a skin problem, the first thing I ask the client is what type of food the animal has been eating," says Dr. Stephen Kritsick, a veterinarian for the American Society for the Prevention of Cruelty to Animals, based in New York City.

Echoes Ihrke: "I wouldn't buy a generic or price-brand food for my own dog even if it said it met the NRC requirement."

This is particularly ironic, considering that most experts claim that the pet food industry is one of the most heavily regulated of all the nation's food industries.

"I think it's safe to say that half the human foods on the supermarket shelves couldn't meet the requirements to be sold as animal feed," says Roger Hoestenbach, chairman of the pet food committee of the Association of American Feed Control Officials. AAFCO is an independent association of state and federal officials that works to create uniform guidelines and regulations for the registration, sale and manufacture of animal feeds and remedies.

Nevertheless, Hoestenbach -- who works for the state of Texas, not the industry -- doesn't deny there are problems, in some cases severe, with generic and price-brand pet foods.

Problems include:

* Enforcing regulations.

The AAFCO itself has no regulatory authority. Nor, for that matter, does the National Research Council, a branch of the National Academy of Sciences. The NRC publishes recommended minimum nutritional allowances for 36 different vitamins, minerals and amino acids.

* Popularity of generic foods.

Consumers have been told repeatedly that generic products -- whether drugs, canned corn or paper towels -- are as good as (and in some cases identical to) their nationally advertised counterparts. The price difference is due to the decreased costs for advertising and packaging, and has no reflection on the quality of the product.

So it's not surprising that most people would believe that generic dog and cat foods are really brand names in plain wrappers. But they're not -- none of the major national producers makes a generic food.

In this case, you do get what you pay for, say the experts. "If you go for the cheap, that's exactly what you'll get," says Hoestenbach. "Cheap foods mean cheap ingredients," which means less nutrition.

And even if the food is nutritionally adequate, the animal may require more food -- i.e., 10 cups of brand X as opposed to two cups of a name brand -- to obtain the required nutrition, so in the end, it's a false economy.

* Palatability.

A lot of dogs and cats simply don't like the taste of cheaper foods -- especially dry generics -- even those that are nutritionally adequate.

And even if pets will eat the food, they may not want to eat it in the quantities required for proper nutrition.

Although each state sets its own requirements for the manufacture and sale of pet foods, the federal Fair Practices in Labeling Act and AAFCO regulations that have been adopted by the vast majority of the states require that every pet food label contain certain information. This includes an ingredient listing, with the most prevalent ingredients at the top, as well as what's called a "guaranteed analysis," which must list the minimum percentage of protein and fat, and the maximum percentage of fiber and moisture contained in the product.

That guarantee, however, doesn't have to list what those percentages mean, so if you're not familiar with the NRC guidelines -- and most pet owners aren't -- the listings aren't going to be of much help in choosing between brand X and brand Y.

What do consumers rely on to make a choice? Frequently it's the nutritional claims on a label.

Most foods contain some type of claim, the most common of which is to the effect that the product "supplies complete and balanced nutrition for all life stages and meets or exceeds the standards set forth by the National Research Council."

This statement means that the food, when given as directed, provides enough nutrients to satisfy not only the needs of the full-grown, moderately exercised house dog or cat, but also the higher nutritional demands of the growing puppy or kitten, the working or hunting dog, and the pregnant or nursing female.

Sometimes, however, the label makes no nutritional claim, and this can be misleading.

"Consumers have grown to expect all pet foods to be complete and balanced," says Duane Ekedahl, executive director of the Washington-based, industry-financed Pet Food Institute. "So they'll see the guaranteed analysis and mistakenly assume that it means that the food is complete and balanced."

The so-called silent label is only one way some pet food producers are getting by on half-truths, says AAFCO's Hoestenbach.

"For example," he says, "a label might say that the food meets NRC requirements -- and it very well may -- but only for maintenance, not for growth or gestation."

In an effort to combat this problem, AAFCO recently adopted a new regulation requiring labels to indicate for what stages a food was "complete and balanced," and if the food was not complete and balanced, that it state that the product is intended "for intermittent or supplemental use only." The bad news is that the regulation has yet to be adopted nationwide.

And the problems get even more complex. Some foods may contain nutrients in the amounts recommended by the NRC, but those nutrients may not be in a form in which the pet can digest and use them.

"You can put an iron bolt in a bag of dog food, then analyze that food and it will come up showing that the iron requirement has been met, but that doesn't mean the animal can digest that iron and use it," says veterinarian Kritsick.

In other cases, ingredients may combine in such a way as to prevent the absorption of certain nutrients. Some scientists now think that the skin condition documented at the University of California-Davis was the result of a zinc deficiency caused not by a lack in the food, but by a high cereal content, making that zinc unavailable to the animal.

The NRC recently issued revised recommendations for dog nutrition that attempt to address some of these problems. Revised cat food recommendations are due out at the end of the year. But, while Dr. James Morris, chairman of the NRC's Committee on Animal Nutrition, says he finds it "highly unlikely that a food could contain the required nutrients and still be nutritionally inadequate," he also says that "the best assurance of the nutritional adequacy of a pet food is that it's passed the AAFCO protocols."

Those protocols, used by virtually all the national producers and some regional ones as well, include extensive feeding trials that weed out deficiencies that don't show up in laboratory analysis.

So what's a concerned pet owner to do?

First, don't panic if your pet is an average, healthy, nonworking dog or cat: The majority of generic and price-brand foods provide enough nutrition for these animals. Most vets advise that generic foods not be fed to growing animals, working animals such as sled dogs or herding dogs, pregnant or nursing females, or older animals, who need less protein of high quality to relieve stress on their kidneys.

Second, watch your pet carefully. A dull coat, loss of energy, or a persistent loss of weight or appetitie should merit a trip to the veterinarian. If you've been feeding the animal a generic or price-brand food, be sure to mention it to the vet.

Finally, if your dog is healthy and you want to keep it that way, advises Hoestenbach, "find a reasonably priced, easy-to-obtain food that the animal does well on, and stick with it." Unlike humans, dogs don't need variety in their diet if what they're getting is nutritionally complete, and a sudden change may even bring on digestive problems.

Make sure the product is labeled complete and balanced for the stage of life your pet is in. If the brand you're using is not a national brand, write to the company and ask if it performs regular feeding trials, and if so, to send you the results.

Because cats can become addicted not only to a single taste of food, but even to a particular texture or shape, experts recommend alternating a few different types, or adding some table foods to the feline diet. The same rules about nutritional adequacy and feed trials, however, should apply for cat foods as well as dog foods.