Breeding Problems with my Lab

Question
QUESTION: Hi,
I have a 3yrs old female black lab, she has had a litter of puppy's and is in heat again. She has been in heat for about three weeks and has been bleeding off and on. It seems that some-days shes out of heat and others shes still really at her peak. my male has mounted her five times now. each time has lasted about an hour. im getting so worried why hasn't she came out of her heat yet?

ANSWER: Hi Kellie

How long between heat cycles has it been?
When did she have her pups?
Has she had a heat cycle since the pups or are you breeding back to back?
What is her exact day in her cycle?

Could she in fact, have an infection? What is the discharge level? Has the blood thinned out or changed color?

---------- FOLLOW-UP ----------

QUESTION: she started on the 31 of august, she is only bleeding a little just a drop her and there. she is a really healthy dog is eating very well i couldn't imagine her having a infection. her last heat was 6 months ago exactly the puppy's were born march 4 and have been gone since June 5 yeah this breed is back to back but after this batch im getter her fixed. it is day 29, some days the discharge is a white,dark dark red, then normal looking blood. don't get me wrong i love my dog so much i just want her to have her chance to experience puppy's one more time. thank you for helping me with my problem

Answer
Breeding back to back can be hard on a female.  And if she was feeding until the pups left, her body will be depleted of important vitamins and nutrient.  This could also explain the reason for the long season.

But as she's only running an extra week, it could be that you miscalculated dates.   

A low grade infection is not indicative of the overall health of a dog and can only be verified by a culture.  When a female is in heat, she has a greater risk of bacteria, germs and dirt getting into her vulva thus causing a infection.