He's also a source of joy for one of Constantino's professors, Michael Kolomiets, who teaches molecular and environmental plant sciences.

"He is literally a moral support for anyone in the lab and is that bond that makes us all closer to each other. It's almost like we see in each other the kids that we forgot we still are," he said. "For me personally, whenever I am stressed, which in our line of work is almost every day, I go down to the lab and see him, play with him and pet him for couple of minutes and I am ready to work again."

Constantino even relates Axel's job to her research, and he's been a topic in some of her grant proposals.

Her work pertains to plant communication through volatiles in response to pathogens, meaning when a plant is being attacked by an insect, it sends out a distress signal to the surrounding plants to begin defending themselves.

One volatile is the smell of freshly cut grass, she said. And just like the plants, Constantino's body also gives off a distress signal that Axel can detect.

"I actually make a distress hormone, I emit volatiles through ketones, and he comes to help me," she said.