Montgomery County's annual rabies vaccination clinics for dogs will be held throughout May.

County residents can get free shots for their dogs from licensed veterinarians, who will use a vaccine officials say is effective for three years for dogs more than 1 year old, and one year for dogs under 1 year old.

The county's animal control law requires all dogs over four months old to have a current rabies vaccination and be licensed. Licenses will be sold at the rabies clinics. The license is valid from July 1, 1982 to June 30, 1983. The license fee for males and spayed females is $6. The fee for unspayed females is $20. If a dog is spayed before the next licensing period, the owner may apply for a $14 refund.

Dogs with three-year vaccines still in effect may be licensed by sending a check and last year's dog tag number to: Department of Animal Control and Humane Treatment, 1420 E. Gude Dr., Rockville, Md. 20850. Proof of vaccination must be submitted if the dog was vaccinated by a private veterinarian.

The following clinics have been scheduled: May 19, 5:30 to 7:30 p.m., Germantown Elementary School; May 21, 5:30 to 7:30 p.m., Northwood High School; May 23, 1:30 to 3:30 p.m., County Office Building Garage; May 24, 5:30 to 7:30 p.m., Magruder High School; May 26, 5:30 to 7:30 p.m., Herbert Hoover Junior High School; and May 28, 1:30 to 3:30 p.m., Rockville Civic Center.

Arrangements will be made at some clinics for the sale of tags for Rockville and Gaithersburg, which require their own licenses. A county fee is not required if a dog is licensed by either city.

For more information, call 279-1823.