i thing my dogs in heat

Question
my dog is 13yrs old she has never been fix she is acting like shes in heat she keeps crying alot.When i let her out she starts digging and then she lies there like she has puppys  is that normal and how long does that last.

Answer
A heat cycle is when the bitch has a vaginal discharge at the beggining of the cycle its red then orangey then yellow to invisable at the end te cycle lasts 2 weeks...be sure Not to let her get pregnant she will Not be able to carry a litter of puppies easily at her age.