PHILADELPHIA — Tucked discreetly on the outskirts of the cosmetics department in the new Macy's in Center City Philadelphia is a sign that the line between human and canine continues to blur.

Right next to the Origins beauty-products display and natural-health guru Andrew Weil's pricey skin concoctions is Up on the Woof, the place to buy shea butter shampoo and paw balm for your pup. With its sky-blue and spring-green packaging, the new department fits so seamlessly among the competing collections of feminine paints and powders that it is a bit of a shock that these products are for pets.

This department — further proof of just how mainstream the trends fueled by undersize, celebrity-arm-candy pets have become — is only Macy's second foray into animal pampering. It opened its first Up on the Woof in New York City about a year ago. The Philadelphia department debuted in August when the grand old Center City store, once home to Lord & Taylor and Wanamaker's, officially became a Macy's. Special touches like this are part of the effort to make the downtown store the region's flagship.

"People like to pamper themselves," said Elina Kazan, a Macy's spokeswoman. "They like to pamper their pooches."

She declined to say precisely how pet-product sales are going, but she said the company was pleased. "It's doing well enough that we want to expand it," she said. "It's something that has a lot of cachet. It's something that has a lot of legs on it."

Up on the Woof is a way for Macy's to grab a small piece of the $38.4 billion that the American Pet Products Manufacturers Association estimates Americans will spend on their pets this year. That would be up by $10 billion since 2001.

Macy's is on the leading edge of a "new wave of retailers who are jumping on the pet bandwagon," said Marshall Cohen, chief analyst for the NPD Group Inc.

Department stores like Macy's once had a tighter grip on their customers, he said. Now, people shop in a lot more places, and Macy's has to offer as wide a range of products as possible to compete.

"They're reaching for growth anywhere they can get it," Cohen said.

Macy's customers shop in a country where they can get a $20.99 Princess Leia costume for their dog at Target or a $70 Gucci dog baseball cap from Neiman Marcus. There are freestanding high-end boutiques for pets. Paul Mitchell now makes pet shampoo, and Omaha Steaks International Inc. offers pet "steak treats." Burberry Group P.L.C. makes a $225 dog trench coat. Land's End offers wild-rose and parrot-green squall jackets for dogs — $49.50 to $79.50 depending on the size of the beast — in its winter catalog for children. The Home Depot Inc. recently added pet supplies to a small number of its stores.

"So many nontraditional outlets are realizing that there's a very short jump to go into pet products," said Bob Vetere, president of the pet-products trade group.

Up on the Woof's prices are only a little indulgent. Its Harry Barker oatmeal shampoo goes for $14.99. Paw balm is $5.99. A dark-gray sweater and cape set goes for $45. Aside from catnip ($8.99 for a 1.25-ounce, sea-green can), there is not much for cats, most of whom would never put up with this sort of thing.

Cohen said departments like Up on the Woof are meant to show customers that a store understands their lifestyle. Retailers hope that some of the emotional attachment people feel for their pets will rub off on the store. That is especially important in Philadelphia, where so many people who come into the new Macy's remember, fondly, its old owners.

Wanamaker's may have brought you that big bronze bird of prey. But Macy's knows how happy those peanut butter biscuits could make your puppy. And you.