The Texas Mountain Laurel is a popular plant because of its purple flowers and artificial grape smell.  Unfortunately, the entire plant is toxic to animals.  The plant contains grayanotoxin, a toxin that binds to sodium channels in cell membranes and changes the permeability.  It affects the nervous system as well as skeletal and cardiac muscle.  Common symptoms of poison ingestion include vomiting, diarrhea, profuse salivation,  weakness, impaired vision and a slow heart rate.  Please seek veterinary care for livestock or pets that come into contact with this plant immediately.  This plant is very toxic.  Don't let the beautiful flowers and sweet smell fool you.   

Reference:
Puschner, B. "Intoxication With cardiotoxic Plants" ACVIM 2007,