Everyone wants a rescue dog. Not everyone can have one.

Relocating rescue dogs “can be a lifesaving thing,” said Sandra Newbury, a veterinarian and director of the shelter medicine program at the University of Wisconsin, Madison. After all, overcrowding at shelters puts more animals at risk for euthanasia.

But she worries that things have gotten out of hand. Overzealous rescue organizations and shelters, under pressure to increase their live-release rates, might be harming animals as well as creating barriers to adoption. “Why would you ever put a dog through transport if you could place it in the local community?” Dr. Newbury asked.

The journey can be perilous, especially for puppies and kittens, which are more vulnerable to stress. Some animals have escaped from the vans transporting them and been hit by passing cars. Others have overheated. In May, 26 dogs died from excessive heat in a vehicle owned by the American Society for the Prevention of Cruelty to Animals while being shipped from Mississippi to Wisconsin.