NATIONWIDE -- Starting in June, United Airlines will make a series of changes to how it transports pets in its cargo hold.

This week United rolled out the new changes to its PetSafe Program, including restricting animals allowed on flights in cargo to dogs and cats only. 

The airline also announced that it would not accept reservations for dozens of dog breeds and four cat breeds because of possible health problems.

The dog breeds targeted are all considered snub-nosed or short-nosed breeds, like boxers, bulldogs or pugs, or strong-jawed dogs like mastiffs. Mixed-breed dogs may also be affected. A full list is on the United website.

Burmese, Himalayan, Exotic Shorthair and Persian cats will also not be allowed to fly.

The airline also announced that it would not transport pets in cargo between May 1, and Sept. 30, for the following destinations because of high temperature concerns: Las Vegas, Palm Springs, Phoenix and Tucson.

United said depending on weather conditions, it may decided to decline to accept a pet or alter a route so that temperatures in cargo are kept at a safe range.

United suspended the PetSafe program in March after the death of a French bulldog puppy that was put in an overhead bin, and a mixup that sent two dogs to the wrong destinations.

The U.S. Department of Transportation says United has the highest number of animal deaths of any U.S. air carrier for pets transported in cargo. But it also transports more pets than other airlines.

United worked with American Humane Association to come up with this new pet policy.

United also made changes to its policy for pets traveling in aircraft cabins in last month.