Questions about shitzu dogs

Question
I have a female shitzu her name is brandie she is 9years old in people years i want to know at what age will she stop going into heat and how do you know what age a dog is in dog years is it seven years for the first year then one year after that please tell me  

Answer
Hello Erika, She can continue going into heat until she dies, Although it may not be every 6 months as before in her younger years.  I have known dogs to go into heat at the age of 14.  As far as how old she is.  You are correct that it used to be for every 1 human year you would times it by 7 in dog years.  However with the care and better food products available now most vets use 5 dog years for every 1 human year.  Thanks for asking, Cindy Lou :)