NEW YORK (CNN/Money) - If a dog is man's best friend, why are so many humans intent on embarrassing their pet pals?

The latest case in point: Halloween costumes for our furry friends are one of the fastest-growing categories in the $31 billion market for pet products.

According to retailer PetSmart, Americans own 350 million pets, which works out to an average of more than one pet per person. Many of those animals get treated like one of the family, which means taking part in holidays.

In a survey of pet owners performed by the American Pet Products Manufacturers Association, more than 60 percent reported buying a gift for their pet within the past year. The group didn't ask how many pets dress up for Halloween, but judging by the amount of companies selling products, the number seems on the upswing.

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If you're interested in dressing your dog for Halloween, the attached photo gallery may provide some ideas. Most pet stores carry a line of such clothing, generally at modest prices.

For pet owners intent on doing this sort of thing, the APPMA offers the following tips for a safe Halloween:

• Don't wait until the big night to try out your pet's costume. Many animals find costumes bothersome. If yours is one of them, it makes sense to know that in advance of the big day.
• Make sure your pet's outfit is not too constricting. You'll have a better chance getting your dog to wear something if he doesn't realize it's there.
• Don't forget positive reinforcement -- have plenty of doggie treats on hand. Human Halloween candies are not for pets, though. Chocolate can be hazardous to their health. Make sure you and your kids remember this.
• Repeated doorbell ringing and children in costume can cause stress for many dogs. If your dog is easily agitated, keep him away from the trick-or-treaters.
• If your pet becomes sullen or surly in costume, just give up.