The SPCA of Texas (http://www.spca.org) handles rescue and investigations teams for eight local counties and you may contact them at 214-461-1850 and by filling out the form at this link: https://www.spca.org/sslpage.aspx?pid=297
If you are outside Dallas, Ellis, Fannin, Grayson, Hunt, Kaufman, Rains & Van Zandt counties, call your local law enforcement. Texas law protects animals from cruelty and abuse. If the situation is an emergency, please contact your local law enforcement authorities immediately.
The Humane Society of North Texas (http://hsnt.org) conducts abuse, neglect and abuse investigations for Tarrant, Parker, Johnson, Wise, Denton and surrounding counties and can be contacted at 817-332-4768, ext. 113 or by reporting online at http://hsnt.org/documents/CrueltyReport.xls. They ask that you report urgent situations such as illegal dog fighting by first calling 911 and then following up to their emergency number (817-891-5911).