Neutering

Question
I had my 2 dogs neutered about one week ago. One day afterwards they humped a female dog. They sleep inside and when the female dog came in the yard my dogs woke us up crying to go outside. I thought that this behavior would stop!!! Will it stop?
One is a Jack Russel (Milo) and the other a cross between JAck Russsel and Sausage dog> They are 20 months old!!!
Please help

Answer
It takes weeks for testosterone levels to drop in the male after neutering; a recently neutered male should not be able to impregnate a female, but it can happen.  The dog that entered your yard was obviously in heat.  If one or both of your dogs locked on her, a mere 24 hours after having been neutered, a pregnancy could still be possible.  Your dogs, if over 18 months of age, will retain "intact male" behaviors (especially going after females in heat) for quite a while.