Safety for females during their season and while nursing.
It is necessary to completely confine your girl when she is in heat. The only thorough way of doing this when she is outside is to put her in a nice long exercise run that is ALL METAL and has a metal top and metal wire floor that are both attached securely all along the way to the metal sides !! We use pipe clamps (tightened with screws) to assure the top and floor is securely attached to the sides of the pen.
We made a 32 ft "run" using 16 ft cattle panels set on two widths of 5 ' each rolled fencing, clamped all along the middle seam so that this "floor" wouldn't curl up in the middle where they join. Along the top is one 5 ft fence panel attached to form a secured "roof". The job was finished by multiple pipe clamps around the top and bottom perimeter of the pen to avoid our ladies squeezing out. (They do have a knack for squeezing out of the tightest spaces !)
Since 2000 I've only had one "accidental" breeding that was between one of my females and our male Big John. In this case, the girl pulled the light weight chain link on the gate and popped the factory fasteners. She continued to pull until a hole was made in the bottom corner of the gate. From this time onwards we've always reinforced our chain link pens and gates with pipe clamps !

Beware of using wood chips for bedding with Pyr moms.
There is a bacteria called Klebsiella that causes mastitis and metritis in pregnant and nursing dogs. It can also cause blood infection in newborn pups. I brought the below article into our vet and he confirmed this is what caused complications in three of our 2006 girl's nursing experiences. This organism enters the trees or cut logs before they are processed. I purchased cedar and pine chips from Walmart in big bags, thinking that I was buying cleaner, better bedding for our girls than if I purchased bags of shavings and chips from our very nice local sawmill. What a discovery ! Spread the news to save your pregnant mom dogs and newborn pups from pain!
The full article where you can read about this is at the following:
© 2007 Foster & Smith, Inc.
To protect your girl's health, please pen her securely. To read more about a transmittable veneral disease that could endanger your girl in heat if she gets with an unknown dog, please click here.