Unless the Texas legislature has changed the laws in recent years, feral dogs in Texas are fair game. In any rural area, any stray dog on one's land has no protection beyond the opinion and judgement of the landowner.
One dog with a collar, just traipsing through, is likely no problem. Any group of dogs, with or without collars, is a problem looking for an opportunity.
People will drive right past an animal shelter/dog pound to throw away the unwanted bow-wow. That generally leads to a dead dog, whether by starvation or a bullet. A house cat can generally survive in the wild--until I shoot him--but a house dog generally won't.
We had a wild pack of feral dogs; about a dozen of them. They'd been seen pulling down a deer, and had been driven away from a colt. I popped a couple of big long-legged hound-types. Looking them over, they were pretty much gaunted. But, in a desert, a pack has to cover a lot of ground for not much available prey...
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