We had our dogs on NWC Naturals Tri Krill pills for over 5 years and just stopped using them this year thinking it might be the cause of one dog's gut issues. There's no way to prove if it was or was not the cause, but by not giving it to our other dog, she came down with oral problem within the year of going off the Tri-Krill. She was 13.5 yrs old and I strongly feel that due to her age, since she was part Chow and Chows have a predisposition to oral issues, if we had kept her on the Tri-Krill, she would not have gotten the issue. I am in huge favor of using these pills with all dogs and am putting our other dog back on them. She is 14.5 yrs old and doing great.