DEAR ABBY: I just read that the San Mateo County (Calif.) Board of Supervisors passed the nation's first law requiring the owners of dogs and cats to buy a breeding license or get their pets sterilized.

The article stated that the Humane Society said it was "fed up" with putting to death more than 10,000 unwanted dogs and cats each year - and in order to coerce the voters, the society published photographs of trash barrels filled with dead cats picked up throughout the Bay area.The society then held a public pet execution at the press conference, injecting five cats and three dogs with poison from a bottle marked "Fatal Plus" as the camera whirred and reporters jotted notes.

Abby, now anyone in San Mateo County owning a cat or dog that has not been spayed or neutered must produce a "breeding license" or face a fine of $500!

Does this sound "humane" to you? Please state your opinion. - HORRIFIED IN REDWOOD CITY

DEAR HORRIFIED: Bow-wow and mee-ow! It's high time someone spoke for the voiceless. Although its approach was somewhat extreme, the Humane Society of San Mateo County rates applause and high marks from this animal lover.

DEAR ABBY: Yesterday, I answered the telephone and patiently listened to a gentleman with a very nice voice trying to sell me a $39.95 book of coupons from the "local merchants." He said if I purchased a book of these coupons, I would be helping a child in his fight against leukemia.

I explained that we were on a very tight budget and I couldn't afford $39.95, but could I send a smaller donation to help the child? At first there was a stony silence, then BANG went the receiver. Abby, that man had actually hung up on me!

I realize that most of these telephone solicitors are just doing their jobs, but I would think they would appreciate being told BEFORE they give their entire pitch that the party on the other end of the telephone is not interested.

Speaking for myself, as a matter of policy, I never buy anything on the telephone. I would never be rude, but I hate to take up their time when I know I'm not going to buy anything. - DENNISON, OHIO, HOUSEWIFE

DEAR HOUSEWIFE: I can't speak for all telephone solicitors, but if I were one, I would not want to waste my time giving my entire pitch to someone who, as a matter of policy, never buys anything on the telephone. A courteous, "I'm sorry, sir . . . ," etc., as soon as one recognizes the caller as a telephone solicitor, would be my recommendation.

DEAR ABBY: Our family is hoping that you can settle a dispute. Our teenage and "20s" kids insist that the message on a postcard is private and should not be read by anyone other than the addressee.

I maintain that any postcard that comes to my house, no matter to whom it is addressed, is fair game for me, or anyone else, to read. What do you say, Abby? - NOSY OR NOT NOSY MOM

DEAR NOSY: Anyone who writes anything of a confidential nature on a postcard and assumes that it will be read only by the addressee knows very little about curiosity, temptation and the human animal.

Everything you'll need to know about planning a wedding can be found in Abby's booklet, "How to Have a Lovely Wedding." To order, send a long, business-size, self-addressed envelope, plus check or money order for $3.95 ($4.50 in Canada), to: Dear Abby, Wedding Booklet, P.O. Box 447, Mount Morris, IL 61054. (Postage is included.)