forget loop unless you want to buy a wool.
There are really only 3 major manufacturers, but we are only dealing with names here. the manufacturers still exist but are owned by another company. think banks, it's just like that.

yes Karastan is one of the top companies out there, and so is lee's.
shaw, tuftex, galaxy, mohawk, krause, bealeau, all make good carpets and so so carpets.

if you want a loop carpet(berber) look at good quality nylon,don't worry too much about brands,as floorcraft says we are down to three major mills who own about 80/85% of the carpet industry,be very careful not to buy an olifin carpet,they dont clean well.
a nylon berber carpet of good quality will cost $30.00 to $40.00 a sq yd.(installed). most nylon berbers are short,tight loops.almost commercial quality,so a dog wont be a problem.....good luck