Pet odor

Have you been to a house that smells very bad. The Pet Odor emanates all over the house that it seems like the odor sticks everywhere you go to. It's kind of hard to make the odor eliminate specially when it's Winter time that we all close the window and doors tightly because we don't want the cold air to come inside the house. My step-son is selling puppies. He had good breeding for good puppies and it's often time his problem because the odor sticks almost forever in his house. He doesn't like other people to visit his house because of the odor. Well good thing that his wife found a good odor eliminator and right now it's working in their house. They could not hardly smell it but sometimes it does and since it's Summer they open all the windows and let the breeze of air cool off the whole house and take care of some odor that is left behind.  I hope that sooner than later it will solve his problem.