ULTRA PAWS DOG PET WOUND BOOT (Large) he width of the foot should be smaller than the boot size. For example, if the foot width is 1 1/2 inches, order an Small at 1 3/4 inches. Small 1 1/4" to 1 3/4" Medium 2 1/4" to 2 3/4" Large 3 1/4" to 4" If your dog is wearing a cast or bandage here are the circumferences that will fit into the different sizes. Small 4 1/2" to 6 1/2" max Medium 6 1/2" to 9 1/2" max Large 7 1/2" to 11" Breathable to allow air to flow freely in and around the wound area - reducing moisture and keeping the wound area dryer and cooler The base features a traction pad with an anti-slip feature to assist indoors, and protection when outside and Elastic sides expand to cover bandage or cast The interior foam pad helps keep the boot securely in place and provide comfort Easy to use with a wide top expands to slip dog's paw into the boot and two generous velcro strips with closures at the front and back