Boarding a Delta flight with your service pooch is about to get tougher.

The airline on Friday said it was implementing new regulations on March 1 for people bringing service or emotional support animals on its planes.

All passengers attempting to board with a service animal will have to show "proof," 48 hours before flying, that the animal is in good health and has been vaccinated. Passengers with emotional support animals must sign a form that the animal is well behaved and won't act aggressively. In addition they have to present a letter prepared and signed by a doctor or licensed mental health professional that certifies they need a comfort pet.

Delta (DAL) said its policy change was prompted by "a lack of regulation that has led to serious safety risks involving untrained animals in flight."

The airline says the number of service animals on its flights has increased nearly 150% since 2015. Delta says it carries more than 250,000 service and support animals a year. Those pets fly free of charge.

"Customers have attempted to fly with comfort turkeys, gliding possums known as sugar gliders, snakes, spiders and more," the airline said in a statement.

Delta says animal incidents on its planes have increased by 84% since 2016. In one incident last summer, a man was hospitalized from bite wounds he sustained when another passenger's 70-pound dog attacked him during boarding, the airline said.

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The new regulations are aimed at protecting "the rights of customers with legitimate needs, such as disabled veterans," Delta said.

Under current policy, Delta, along with United Continental (UAL) and American Airlines (AAL), requires passengers to submit proof from a health professional 48 hours in advance that a service animal needs to fly with its owner. Passengers with emotional support pets are not currently required to promise that their animals will behave.

United told CNNMoney in a statement it is "reviewing our existing policy and plan to share more soon." It did not give additional details.

American, the largest U.S. carrier, said "we agree with Delta's efforts." "We are looking at additional requirements to help protect our team members and our customers who have a real need for a trained service or support animal," a statement said.

The airlines have a financial incentive for tightening rules about animals.

Delta passengers flying in North America have to pay a one-way fee of $125 to carry on their dog, cat or household bird on a plane if the pet is not registered as a service or support animal.

But by registering a pet as an emotional service animal -- which can be done online, through organizations like The Official Emotional Support Animal Registration of America -- the pet can ride alongside you for free.

Under federal law, an airline must permit the service animal to accompany a passenger with a disability at any seat on plane unless the animal obstructs an aisle or area used for emergency evacuation.

However, the regulation also allows airlines to determine what factors would disallow an animal from boarding a flight, including "whether the animal would pose a direct threat to the health or safety of others" and "whether it would cause a significant disruption of cabin service."

Ruth Lowenkron, the director of the Disabilities Justice Program, part of New York Lawyers for the Public Interest, said she worries that new regulations are putting an unfair burden on people with legitimate disabilities.

"Delta might be successful in ensuring that people who do not have disabilities wont be able to pretend they do to bring their animals on the plane, but it will also get in the way of the rights of people who do have disabilities," Lowenkron says.

Katie Tastrom, a lawyer and advocate for people with disabilities, says that poorly behaved service animals are the ones that are prompting this kind of reaction from airlines.

"The solution should involve poorly behaved animals not putting an increased burden on disabled people," Tastrom says.

Delta is also creating a Service Animal Support Desk for customers that will verify documentation is received and confirm the customer's reservation to travel with the animal before they arrive at the airport.