Texas Law last time I read it stated that a land owner can only shoot a dog if it is harrassing livestock, Cows, Horses ect and in the defense of the livestock. If someone just plain ol shoots your dogs for being on the wrong side of the fence I think you got yourself a good ol case of animal cruelty if you can articulate it well enough. As bad as I hate em you could really push the issue with a lawyer and make the guys life a living hell along with takin him to civil court as well and suing his butt off for liability and damages to your property. The guy up front making a outright threat to you would also be good ammo that he wasn't protecting nothing, just plain ol shootin up a man's dogs. If all else fails...good lord please forgive me for sayin this one but ....Tell the Humane Society and let them start banging drums and lighting candles. LOL their always up for a good fight. Just tell them your dogs was lost and was making the great journey home to you and little suzy..
FYI here is some good reading:
The precedence for this was set by Bueckner v. Hamel in 1994,
http://www.animallaw.info/cases/caustx886sw2d368.htm. "Texas law allows persons to kill without liability dogs that are attacking domestic animals. However, the attack must be in progress, imminent, or recent. This defense does not apply to the killing of dogs that were chasing deer or non-domestic animals." This case is essentially identical to what is being proposed, except the hog dogs weren't even chasing deer, just running past a feeder.
