The KONG Extreme Your Dog Will Love You For It! Originally developed for the toughest K9 and military dogs, the KONG Extreme is the strongest dog toy on the market. We took the most durable rubber and made a dog toy that will stand up to the most voracious of chewers, from Jack Russells to Great Danes. KONG rubber toys are proudly made in the USA, and have been recommended by vets and trainers more than any other dog toy. KONG‚ performance and durability is legendary. Dogs Love KONG Extreme. Dogs Need KONG toys. KONG toys are widely used as therapy for prevention of boredom, separation anxiety, and other behavioral issues. Providing food or treat-stuffed KONG toys for your dogs can keep them contently busy working, and out of trouble for long periods of time.