They are gonna kill it....

as sad as it is for the pups, your within your rights to shoot them if they are on your property

(but i seem to remember you having dogs that are more then capable to handle things themselves)
If the smaller dog does stick it's head thru the fence and Shelby is there it is not going to be pretty. I talked to the new folks down the road few days ago...he told me that these dogs have been on his property. He doesn't have any fencing yet...but he has a couple kennels for his pups. He is working on teaching his pups the property boundries...but is more than concerned about these 2 dogs creating problems.
What's funny about our pups...when they are out of our yard they are not the least bit aggressive towards other dogs...that approach them in a non-aggressive matter. Last we had Shelby to the Vet....there was an older Beagle mix...Shelby went up and sniffed it, let the other dog sniff her...and then Shelby put her chest on the ground in a very playful manner...they are just EXTREMELY protective of their property. I really don't understand how folks can think it is OK to just open the door and let there dogs wander thru the entire 'hood.