I had a old female lab that lasted till she was 16 and she retired from hunting at 12 and I thought well she doesn't need the collar anymore so I stopped using it. Well she'd be out in the yard snooping around and I noticed that she was getting deaf and her eyesight was failing and I thought you know I'm going to try that collar on her again, ya know her hearing and eyesight suddenly got a lot better. LOL,