By investigating the connection between hormonal levels in people and their animals, psychology researchers at the University of Texas at Austin may be able to provide hormonal clues into who has the potential to abuse their pets and how this abuse might be prevented.

Robert Josephs, associate professor of psychology, and Amanda Jones, graduate student, examined how testosterone levels influence pet owners' behavior and, in turn, how they affect the hormonal changes in their animals during stressful situations.

Their findings appear in a paper titled, "Interspecies Hormonal Interactions Between Man and the Domestic Dog," in the current issue of Hormones and Behavior, a biology journal.

The researchers found men's testosterone levels determined their behavior toward their dogs, after the dogs performed poorly in a statewide agility competition. Men with high levels of testosterone punished their dogs by hitting them and yelling at them whereas men with lower levels supported their dogs by petting and praising the losing animals.

Punished dogs showed an alarming rise in the stress hormone cortisol, a neurotoxic substance that can lead to destruction of cells in the hippocampus, leading to memory deficits. Chronically elevated cortisol levels also weaken the immune system. These consequences might be especially critical for dogs in high stress jobs in which memory and health are critical, such as bomb-sniffing, police and guide dog environments.

Although there is much research demonstrating how changes in an individual's hormone levels influences behavior toward another individual of the same species, this is the first research to examine effects across the species boundary.

"Hormones play powerful roles in interactions from mating to aggression within species. Obviously, people also have the potential to influence stress in other animals," Josephs said. "This study delineates conditions under which man may not always be dog's best friend."

To guard against chronically elevated levels of cortisol in their dogs, the researchers suggest that people who are at risk for reacting negatively in stressful situations try to avoid them or attempt to consciously regulate their behavior during stressful periods and learn to provide support by playing with or petting their dogs.

The researchers speculate these findings may provide insight into parent-child relationships, as well.

"Sometimes parents such as little-league dads or cheerleader-moms invest heavily in the competitive performance of their children," Josephs said. "It is important for parents to enjoy themselves and to not take a child's performance too seriously."