• by Sarah Mahoney  @mahoney_sarah, March 30, 2007

At last, there are happier reasons to visit the pet store than to trade in potentially poisoned dog food. Tomorrow, Petco is sponsoring its annual National Hamster Ball Derby, in which contestants--in those little plastic balls--will race down eight-foot tracks.

The top three winners at each Petco location will get prizes. Coupons for free hamster treats, redeemable only March 31, are posted at Petco's Web site.

Last year's event--a hoot for everyone involved, judging by YouTube appearances--drew more than 14,000 of the nocturnal rodents. More importantly, it enables Petco to target an increasingly significant segment of the pet-care market.

Overall, pet ownership is at an all-time high, says the American Pet Products Manufacturers Association. And just as Americans are becoming increasingly enamored of smaller dogs (earlier this year, the American Kennel Club reported that the tiny Yorkshire Terrier had leapfrogged both the Golden Retriever and the German Shepherd in popularity), they're also buying more smaller animals.

The "small animal" category includes not only hamsters, but rabbits, gerbils, guinea pigs, and other rodents, as well as ferrets and chinchillas. There are now 18.2 million such pets in the U.S., compared to 16.6 million birds, or 11 million reptiles. (For the record, freshwater fish are still the most popular pets, with 139 million in the U.S., followed by 90.5 million cats and 73.9 million dogs.)

Owners of America's 9.6 million pet hamsters are especially avid--and spend more than $336 million annually on supplies and toys, from Hamster HoneyTreat Sticks (gnawing keeps their teeth sized correctly), multi-floored condos and, of course, racetrack paraphernalia.

"Hamsters are popular because they are such a good starter pet for young families," says an APPMA spokesperson.

The Petco Foundation is in the middle of its annual "Spring A Pet" fund-raising campaign, which collects funds that go directly to local animal shelters. Last year, it raised more than $1.7 million. The campaign continues through April 8.