Shoppers buying a dozen eggs these days not only have to decide whether they want organic, free-range or cage-free. They also have to choose among cartons with labels like “American Humane Certified,” “Animal Welfare Approved” and “Certified Humane.”

As the number of consumers concerned about animal welfare grows, such labels, or seals, as they are known in the business, are spreading like kudzu on packages of meat and eggs in the refrigerated cases of grocery stores, to assure shoppers that the cattle, pigs or chickens were treated well.

But the labels may just as easily sow confusion or even mislead shoppers, who probably know little or nothing about the small number of organizations that create most of them and police the food producers that use them.

“Consumers are looking behind the barn doors at these factory farms, and they don’t like what they’re seeing,” said Daisy Freund, the director of farm animal welfare at the American Society for the Prevention of Cruelty to Animals, which created a website last year to help consumers navigate the seals. “Unfortunately, we know that when they hit the grocery store, they’re faced with a profound lack of transparency, accountability and, in some cases, downright deception when it comes to statements on packaging about humane treatment of animals.”