Rat terriers are small dogs with a muscular build. They have a variety of acceptable coat colors, including solid red, chocolate, sable and pearl. They come in three sizes: standard, midsized, and toy. The ‘toy’ rat terriers are about 8 inches tall & weigh between 4 to 6 lbs. Standard rat terriers stand 14 to 23 inches tall & weigh 12 to 35 lbs.