Dec. 21, 2017 -- More and more people are flying with pets they call necessary for emotional support.

Sharon Giovinazzo goes so far as to call them something else: four-legged terrorists.

That may seem harsh. But Giovinazzo, who is visually impaired and travels at least once a week in her job as president and CEO of World Services for the Blind, says she was recently walking through an airport with her service dog Watson when a small dog came running out of a gate waiting area and lunged at them, biting Watson under the chin.

Luckily, the bite wasn’t serious.

But Giovinazzo says she was horrified and rattled.

She talked to the dog’s owner, who quickly apologized. “I said ‘Apology accepted, but your dog should have been secured.’ ”

“The owner said ‘but this is my service dog.’ And I said ‘No, no, no. That’s your dog that you don’t want to put in a kennel and you went out and bought the equipment you need off Amazon, and you’re getting away with it.

Giovinazzo suspects there was a big difference between Watson -- bred and trained to be a service dog that performs a task for someone with a disability -- and the dog that attacked him.

Airlines report more and more people are taking pets on planes by calling them emotional support animals. Such animals don’t have to perform any tasks or services for their owners. Instead, a licensed therapist writes a letter certifying that the person traveling with the animal has a mental illness -- like PTSD or anxiety -- that the animal soothes by its presence.

In 2015, one major airline carried more than 24,000 emotional support animals, compared with about 14,000 service animals, according to the International Air Travel Association.

Thanks to a federal law, emotional support animals are allowed to board a flight at no extra charge. They can sit on the floor at their owner’s feet, or in their laps, if they are small enough.

Not everyone is happy about that.