Female Yorkies go into heat about twice a year, or every six to eight months. Yorkies begin to go into heat when they are 5 to 14 months old.
A Yorkie's heat cycle lasts from two to four weeks and may be marked by a small amount of bloody discharge, ranging in color from red to pink. The dog may seem moody, quiet or tired during this time, or show no change in behavior at all.
A Yorkie can get pregnant at any time during heat, and if an owner is not planning to breed his Yorkie, it is recommended that he gets the dog spayed as soon as possible.