Defending your pet, while on your property, against a person who is actively trying to kill/steal the pet?

I live in TX and there are reports of a person going around killing animals. Would I be justified in using deadly force against a person, while on my property(backyard), who is actively trying to kill/steal my dog? I'm almost certain that pets are considered property in TX. I'm also certain that I'd be justified during nighttime, but would during the day change things? Just want to see if someone can clear this up for me. Tried reading the Penal Code but it wasn't completely clear. via /r/CCW http://ift.tt/2t0GGG8