if my dog is a year and she hasnt gone into her second heat what do i do

ive had my rhodesian pit for almost a year now and when i got her she was 2 months about 3 or 4 months after i had her she went into her first heat ive had her for almost a year now and she is a year and 2 months but she still hasnt went into her second heat while her sister (we got 4 pups all from the same littler at the same time cause we didnt want to seperat them) has gone into heat about 2 or 3 months ago but she hasnt and im starting to really worry about her she is healthy so why didnt she go into heat with or shortly after her sister should i be worried or am i just to protective of her

Asked by Member 1127832 on Sep 7th 2012 in Pet Insurance