Halloween isn't just for humans anymore, as millions are getting their pets in on the action

Key Points
  • With Americans projected to spend more than $9 billion on Halloween this year, pets are getting in on the action.
  • One estimate shows pet costumes will account for around $440 million in spending.
Pippa Stevens | CNBC

Americans are expected to spend a record $9.1 billion on Halloween this year — and that's not just on kiddie costumes, candy and decorations.

It might seem like all fun and games: but the business of pet Halloween is no joke. The National Retail Federation recently estimated 16 percent of Americans plan to dress their pets in Halloween costumes this year, spending around $440 million on a trend that's expected to continue growing in popularity.

This year's spending is a nearly 5 percent jump from 2016's $420 million and has doubled since 2010, when the NRF first began asking about pet costumes.

Thanks to traditional pet supply stores like Petco, as well as Amazon and Etsy, the costume choices are limitless: Consumers are dressing their pets up as pumpkins, food, other animals and even superheroes.

Spending nearly half a billion dollars on animal costumes might sound over the top. Yet the amount of time, energy and money people are willing to spend on doggie dress-up was on full display recently at the 27th annual Tompkins Square Halloween Dog Parade in New York.

The highlight of the event — which was held Oct. 21 and attracted 25,000 spectators — is a catwalk where dogs (and their often equally dressed-up owners) show off their costumes in front of judges and revelers.

Costumes of national figures and food were especially popular, with hot dog costumes particularly favored by dachshund owners. These garments typically consisted of one-piece slip-ons that can be found in stores.

One owner said he chose a hot dog look because it was easy to repeat from year to year. His dog Oscar (pictured below) has worn the same outfit for six consecutive Halloweens.

Pippa Stevens | CNBC

Dogs masquerading as other members of the animal kingdom was another popular choice. Spiders, lobsters and lions were aplenty.

Pippa Stevens | CNBC
Pippa Stevens | CNBC

For the more ambitious dog owners in the crowd, family costumes were a huge hit.

One couple came dressed as "Game of Thrones" characters Jon Snow and Daenerys Targaryen, with their dog Charlotte playing the role of a dragon. Her owner, Laura Ann, purchased the costume from Etsy.

While the dog's costume was relatively inexpensive, Laura Ann estimated that she spent around $300 for all three costumes combined.

Angela, Ian and four-legged Penny came dressed as three of the four ninja turtles. Like Laura Ann, Angela bought her dog's outfit online, although she chose Amazon instead of Etsy. In total, she estimated spending around $100 on the three outfits.

While they're not planning to recycle the look again next year, they do think they'll once again dress as a trio. "We like having family costumes," she said.

Going for a more regal look, Beth dressed up as Belle from "Beauty and the Beast," with her pitbull Sterling playing the role of beast.

She spent upward of $200 on their costumes, but noted that it was a "really good value" because they could wear the outfits in the days leading up to the 31st -- and perhaps again next year too.