Tex. Agriculture Code § 161.048

(a) An agent of the commission is entitled to stop and inspect a shipment of animals or animal products being transported in this state in order to:

(1) determine if the shipment is in compliance with the laws and rules administered by the commission affecting the shipment;

(2) determine if the shipment originated from a quarantined area or herd; or

(3) determine if the shipment presents a danger to the public health or livestock industry through insect infestation or through a communicable or noncommunicable disease.

(b) The commission may detain a shipment of animals or animal products that is being transported in violation of law or a rule of the commission. The commission may require that the shipment be unloaded at the nearest available loading facility.

(c) The commission may not inspect a railroad train at any point other than a terminal.

(d) The commission may post signs on public highways and use signaling devices, including red lights, in conjunction with signs, if necessary to effectively signal and stop vehicles for inspection.

(d-1) The commission may enter into an agreement with a corporation or other private entity to provide goods or services for the establishment and operation of checkpoints or the performance of inspections under this section.

(e) In this section, "animal product" includes hides; bones; hoofs; horns; viscera; parts of animal bodies; litter, straw, or hay used for bedding; and any other substance capable of carrying insects or a disease that may endanger the livestock industry.