Texas' outdoor annual does mention hogs. The are basically unregulated. no closed season and bag or possesion limits.
below is copied and pasted directly from the Texas outdoor annual put out by the Texasarks and Wildlife;

EXOTIC ANIMALS AND FOWL
Exotic animal refers to grass-eating or plant-eating, single-hoofed or cloven-hoofed mammals that are not indigenous or native to Texas and are known as ungulates, including animals from the deer and antelope families that landowners have introduced into this state. Includes, but is not limited to feral hog, Aoudad sheep, Axis deer, Elk, Sika deer, Fallow deer, Blackbuck antelope, Nilgai antelope, and Russian boar. Exotic fowl refers to any avian species that is not indigenous to this state, including ratites (emu, ostrich, rhea, cassowary, etc.).
There are no state bag or possession limits or closed seasons on exotic animals or fowl on private property. It is against the law to:
Hunt an exotic without a valid hunting license.
Hunt an exotic on a public road or right-of-way.
Hunt an exotic without the landowner's permission.
Possess an exotic or the carcass of an exotic without the owner's consent.
Penalty: A person who violates these laws commits an offense that is a Class A Parks and Wildlife Code misdemeanor ($500-$4000 and/or up to one year in jail).
The Texas Animal Health Commission (TAHC) regulates the movement of feral swine for disease-control purposes. For more information please call TAHC at (800) 550-8242 or visit the TAHC Web site.