how many litters can a dam have

Question
how many litters can a female safely have. I have a female that is going to be 5 in march and she has had 3 litter already.  Should i have her fixed or is it safe for her to have another litter.  Her last litter she had 3 healthy babies!

Answer
Lucia,

She should be able to have puppies safely until she reaches the age of seven.  Some people will breed longer and some shorter depending on the female and how often they have bred them.  You seem to be a responsible breeder so I think you should trust your instincts.