Good for you for taking in the stray. People can be horrible.
I commend you, fellow Houstonian.
PS: there is now a product that will tell you the ancestry of your dog; you take a mouth swab and mail it in and they look for genetic markers.
I plan on using it soon: I have two pups and their "woodpile" is confusing: They are siblings from the same litter. One is supposedly 50% Pyrenees/25% Lab/25% Spaniel, and the other, (from a different father we surmise) is 25% Spaniel/25%Lab/50% Satan.
We saved them from a farm where they had eaten poisonous Poke Berries; their other littermates died and their mother was killed by a vehicle. The farm owner used the dogs there to fight off the coyotes and did not consider their parents as pets.
They were free, but re: their vet bills, they were the best $1200 I ever spent.