Pets as stress relievers

It's been said that owning, and caring for, a pet can lessen the stress that accompanies daily living for many people. The writer believes this to be so inasmuch as having the animal/bird/fish right there at the time the tension is mounting can have a calming effect of quite some proportions and maybe prevent rise in the blood pressure (of the carer, not the pet). Regrettably, when we find ourselves in some emotional situation, our pet just doesn't happen to be along. That's the 'here and now' scenario; whether having a pet has a permanent or long-term calming impact on you perhaps depends on how highly-strung you are as a person, how easily you lose your temper, or resort to tears in a crisis. It would be a matter of degree in any case - just what amount of stress relief the pet affords. People often talk to (with?) their animals or birds (not sure about fish) and chances are this comes about as a mini stress-reliever, without the person even recognising it as such. And of course someone may speak to an animal (horse) or bird (Joe Whistler) where it isn't a pet - it might be owned by another person or be 'in the wild'. How about insects, or similar? Who finds their pet spider calms them down?