I usually do not have a problem with torn blankets except for the time my Standardbred mare accidently got her leg strap caught on her water bucket handle and she spooked when she couldn't get free. the door was open to the paddock when she bolted out and I heard a loud rip! I always keep an extra clean blanket on hand when they get too dirty, so I put another on and made sure after that her leg straps were always snug enough not to snag on anything again.
we often cover all our buckles with electrical tape or hockey tape , it keeps the straps from coming loose if you cant check on a daily basis