I am writing on behalf of members of the staff of the Montgomery County Humane Society concerning the article by Laura Sessions Stepp ''Goodbye, Gretchen'' {Style Plus, Nov. 15}, about a family that gets a puppy, then gives it away when it grows up. This article, although meant to be touching, upset us terribly.

What the Stepp family did is over, but we would like to offer some suggestions for families who might find themselves in the same situation: Adults in the family, not children, must have the commitment to care for the pet. If size is of paramount importance, then get a full grown dog, so there will be no question as to size. If you get a pet from an animal shelter or a breeder and cannot keep it, contact the shelter or breeder. Most local shelters and all quality breeders require that an unwanted animal be returned to them. If your dog is about a year old, and you're at the end of your rope, don't give up! This is your dog's adolescence. Most behavior problems at this age can be corrected easily with guidance from a good trainer and a little work and commitment on the part of the owner. The MCHS offers free monthly seminars for dog owners, which give the owner a chance to talk with a professional trainer about how to correct behavior problems. Never give or sell a pet to anyone without checking him out thoroughly. Unfortunately, suppliers for laboratories, dog fighters and other like individuals often respond to ads in the paper. Others who respond may be irresponsible or neglectful. Get references from a potential adopter's veterinarian. Get identifications from the adopter and visit the adopter's house before placing the pet. Ask about prior pets and what happened to them. A caring new owner will be delighted at your concern and will cooperate fully. Only people who have something to hide will be reluctant to give you this information.

''A home in the country with plenty of room to run'' is not the answer. An untrained, undisciplined dog is a liability on a farm, chasing livestock and destroying crops. A dog running loose in the country usually has a short life. Cars, theft, fights with other animals, disease and irate neighbors take their toll. An experienced rural person will not let a dog run loose for these very reasons. Often the suburban dog with good committed owners gets more exercise than does the chained or penned rural dog.

Owning a pet involves hard work and responsibility. By the same token, placing a pet in a new home also involves hard work and responsibility. Not every family has the time and commitment to have a pet. Children learn a far better lesson in responsibility and courage when the family forgoes getting a pet when the family is unable to make a lifetime commitment to that pet.

MARY IRENE ENO Director of Humane Education and Public Information Montgomery County Humane Society Rockville