Texas is complicated. In most of Texas it is legal to use up to two dogs off lead to find wounded deer. There are a number of counties in East Texas (the Piney Woods Country) where this is not allowed. In these counties there is no legal provision for tracking dogs, but it seems to be tolerated if the dog is on a leash. The use of firearms at night is a grey area.
State Regulations: http://www.tpwd.state.tx.us/
Green — Tracking allowed
Red — No Tracking allowed
Gray — Tracking allowed under certain circumstances or in certain areas of the state but not all