The Denver Post said Frontier Airlines, which operates more than 550 flights from Denver International Airport, Milwaukee's General Mitchell International Airport and Kansas City International Airport, will charge $US75 ($84) each way for pets.

Small dogs, cats, rabbits, guinea pigs, hamsters and small household birds will be allowed to travel if they are in approved carriers that fit under seats. But snakes on the plane have been outlawed, along with insects, spiders and amphibians.

Frontier - which has animal designs on its planes' tails - will also allow larger pets that weigh more than 9kg (20 pounds) as checked baggage for $150.The airline had once allowed pets on their planes but canned the cabin rides two years ago. Now they have returned once again.

"We have spent a lot of time listening to our customers and determining what would make their travel experience even better," said Ian Arthur, vice president of marketing and branding.

"We received a lot of feedback on our pet policy and determined that pets would be a welcome addition to the Frontier travel experience."

The Denver Post reported that complaints from passengers rose last year when Southwest airlines began allowing animals on their planes. Barking and odors from dogs, plus exacerbated allergies and asthma in human passengers, were among the issues.