If you're worried about your blood pressure, a pet cat or dog may control your pressure during stressful times.

That, at least, is the implication of research presented by social psychologist Karen Allen to an American Heart Association meeting on Nov. 7. Her work follows several other studies that suggested pets help control blood pressure. But while previous studies compared pet owners to non-owners, this was the first to look at what happens when a non-owner gets a pet.

As her guinea pigs, Allen, a researcher at the State University of New York at Buffalo, recruited 48 New York City stockbrokers who had hypertension -- high blood pressure. The brokers, 24 men and 24 women, lived alone, and their average resting systolic pressure was 160 millimeters of mercury, well into the danger zone. (Systolic pressure is the higher of the two numbers in a blood-pressure reading.)

As the experiment began, the subjects started controlling their blood pressure with lisinopril, an inhibitor of angiotensin converting enzyme (ACE). Although lisinopril reduced systolic pressure to an average of 123 mm, it was far less effective in controlling the rise in pressure that occurs during stress.

Better than drugs!
At the outset, half the broker-guinea pigs were directed to choose a cat or a dog as a pet. The fun part came when these guinea pigs were asked to do mental arithmetic -- or (we love it!) -- to respond to an experimenter who, posing as a client, demanded: "Upon your advice, I lost $86,000. What are you going to do about it?"

The demand stressed the non-pet owners enough to essentially cancel the benefit of the ACE inhibitor, Allen says, yet the systolic pressure among pet owners rose only 9 mm. Furthermore, their pulse rose by 10 beats per minute, less than half the 21-beat rise seen in the control group.

In other words, pets were much better at reducing the stress-induced rise in blood pressure than the drug.

Cats rule? Dogs drool?
Oddly, dogs and cats were equally effective at controlling blood pressure, and even more oddly, owners got the benefits even if they were not paying attention to the animals. (Allen says she was present during the pressure measurements, and the pets seemed more interested in her than in their owners.)

Why do pets work? Allen says other observations during the study indicate that they offer a non-judgmental presence that influences how owners see difficult events: "To have something in your life that's totally on your side has a very powerful effect. Somehow their presence changes your perception of what's going on from a threat to a challenge."

Hypertension being a serious problem that can lead to deadly strokes, Allen stresses that cats and dogs are not intended as replacements for drugs in controlling blood pressure, but rather as supplements.

Still, even if Shoo-shoo the poodle would be chary of the chaos of a stockbrokerage, pets may eventually play a greater role in stress reduction. It's possible that Shoo-shoo's photo -- or even a poodle in the form of a stuffed animal -- may provide on-the-job restraint for soaring blood pressure.

Despite the findings, Allen does not argue that pets will work for everyone. "If you treat a pet as a piece of furniture, you will derive roughly as much benefit as you would from a sofa."

A couple of final notes: when you pet your pet, your blood pressure probably falls -- as does your pet's. And when the stockbrokers in the control group learned of Allen's results, many went out and -- you guessed it-- invested in some pets of their own.