I started using bullymax after it was recommend by vet (I brought in a rescue dog for a checkup and he was really underweight). After about 10 days his energy level & spirit really picked up. He was becoming more playful, and adding obvious weight. after 65 days, we took him back into the vet and he was shocked that it was even the same dog. His weight at the first visit was 46 lbs. His weight at the second visit was 61.5 lbs. I use this product year round and would recommend it to every dog owner, not for just dogs that sick or underweight.