Tex. Parks and Wildlife Code § 62.106

(a) This subchapter does not apply to a peace officer or other employee of a municipality, a county, or this state, or a person acting at the direction of such an officer or employee, who, while acting in an official capacity or at the direction of such an officer or employee acting in an official capacity, injures or kills a dangerous wild animal that the officer or employee reasonably believes to present, under the circumstances, the possibility of danger to the public. A person described by this subsection is immune from criminal or civil liability and from prosecution or civil suit for causing injury or death to the animal.

(b) This subchapter does not apply to a licensed veterinarian or an employee of a sanctuary exempt from federal taxation under Section 501(c)(3) of the Internal Revenue Code of 1986 (26 U.S.C. Section 501) or of a facility accredited by the Association of Zoos and Aquariums, who, while in the course of such employment, humanely euthanizes a dangerous wild animal to eliminate the suffering of that animal due to illness or injury. A person described by this subsection is immune from criminal or civil liability and from prosecution or civil suit for causing injury or death to the animal.