TexasCHLforum.com

txinvestigator wrote: However, Texas use of force laws also has a clause called Necessity;

§ 9.22. NECESSITY. Conduct (shooting the dog) is justified if:
(1) the actor reasonably believes the conduct is
immediately necessary to avoid imminent harm;( that harm being mauled by the dog)
(2) the desirability and urgency of avoiding the harm
clearly outweigh, according to ordinary standards of
reasonableness, the harm sought to be prevented by the law
proscribing the conduct; (the harm avoided by the law proscribing killing or injuring an animal is reasonably less than the harm caused by YOUR being mailed by the dog) and
(3) a legislative purpose to exclude the justification
claimed for the conduct does not otherwise plainly appear. (it does not appear the legislature wanted to keep people from protecting themselves from dogs attacking them.)

It is clear to me that a large dog attacking you would justify your injuring or killing said dog.

I don't see this as a gray area at all though. Plenty of cops have shot dogs, and the danger of dog attacks is part of LEO training.