WHEN THE Maryland Feline Society holds its 14th Household Pet Cat Show Sunday, its president, Trish Merryman, and her husband Richard, have a double interest:
Trish is organizing the show, which is no small task -- it's called ''Whiskers & Witches'' and has a Halloween theme -- and Richard is grooming their own household pet for competition.
The cat's name is Scottie and he is one of two stray cats the couple rescued from the streets.
''Richard found Scottie, who is about 2, last year in front of Scotty's Sports Bar on Harford Road and Moravia Boulevard and brought him home,'' says Trish.
Scottie's breed is that of a red tabby, mostly white with patches of red, explains Trish, who has owned cats for about 15 years and has been a member of the Maryland Feline Society for about 10 years, having held most positions including her present one as president. She is also the editor of the society's monthly publication, Cat Chat.
The couple, who have been married for 10 years, live in north Baltimore. He works for the State Highway Commission and she keeps cats and house, she says.
Richard, who can't turn away from a cat in need, also rescued their 11-year-old Lucky, who was in competition in the household pet show two years ago.
''Everyone gets their turn,'' says Trish.
Lucky, a brown mackerel tabbie, is a success story. Richard was working for a foundry at the time and Lucky was a cold stray who, in seeking warmth in the foundry, fell into one of the melting pots and was badly burned. Richard saved her, rushed her to a veterinarian and the two nursed her back to health at home.
The Maryland Feline Society holds an annual show for the household pet cat, which is a cat whose breeding was at random or unknown. Some may have all the conformations of a specific breed but they are not registered or eligible for championship points.
On Sunday, there is an entry of 100 household pet cats like Lucky and Scottie. Entries are closed. Show hours are from 9 a.m. to 5 p.m. in the gymnasium at Loyola High School, Blakefield, at Charles Street at Chestnut Avenue.
Four rings of judging will include specialties, all-breeds and judging of cats adopted from a shelter. At 5 p.m. the final Best of Best awards will be presented by Glen Beck and Larry Wax of radio station B-104.
Admission is $4 general, $3 for children under 12 and adults over 60. Also, those who bring a cat food donation, dry or canned, will get a $1 admission discount. The cat food will go to humane organizations benefiting cats.
The Maryland Feline Society meets monthly, usually on the third Wednesday at 8 p.m. in the Bradford Federal Savings and Loan building at 6900 York Road near Towson. Most meetings include a speaker or demonstrations regarding care of cats.
The October meeting is tonight at 8 p.m., and the program is entitled ''Getting Your Cat Ready for the Cat Show.'' Several members will bring their cats to demonstrate grooming procedures. ''Grooming supplies and cat cages are for sale at a nominal cost," says Trish. "And anyone interested is welcome.''
For show information call Pat Steckman, show manager, at 988-9422 or Bettye Campbell, entry clerk, at 256-4293.