OrthoVet Rear Leg Splints are designed to extend up and over the Hock or Heel of the animal to support a variety of lower limb injuries. The splints do extend completely under the foot. The OrthoVet splint will not support injuries to the Knee or Stifle on the limb. Please refer to our Links page for other web site information on Knee splinting. “A” Measurement: Total Length of splint “B” Measurement: Point of Hock to end of Toes Sizing Information: To review our Sizing Page, click here. Feline Size: For cats & small dogs less than 10 lbs. X-Small dog: For dogs 10-25 lbs. Small dog: For dogs 25-40 lbs. Medium dog: For dogs 40-65 lbs. Large dog: For dogs 65-85 lbs. X-Large dog: For dogs 85+ lbs. *XX-Large dog: For dogs 120+ lbs. *The XX-Large size splint is a custom made item. These are fabricated individually. Please allow 2-3 extra business days for shipping on this size.