How do I know when its time to put my 13.5 year old dog down? He has bone cancer.?

You will know when it is time for your friend to cross the Bridge. They get a look in their eyes. They are asking you to help. You will just be able to tell. Don’t second guess yourself after the fact. Your vet will be able to console you. As for meds, I would do whatever I could to make your dog comfortable. I agree and would not amputate or do chemo. 13-1/2 is a ripe old age, even tho we never have enough time with our dogs.
I am sorry for you and speak from experience. Treasure the time you have left.
My vet said it best when she said, "When they just go to sleep, it is easier on us but harder for them. When we put them to sleep, it is harder for us but easier for them. We are responsible for making it as easy for them as possible. That is what it is to love a pet."

Covert the dogs age into human years, then think about how long you would like to live. Then once you have made that determination think about how long you would want to life with such a horrible cancer. I mean if you love something, the hardest thing is letting it go. But sometimes the hard things are the necessary things.

Each animal is different. Usually an animal will signal that they are past the point of enjoying life by withdrawing or becoming less social. You don’t need to let it go that far though, and can decide based on quality of life. Sometimes the ill animal does not withdraw and instead seeks comfort and becomes more clingy. This is also a sign they need help, but are not quite to the point of not tolerating living anymore.

My recommendation is to tell your vet you would like a few more GOOD days/weeks before you let him go. It sounds you would like a little more time, but he is in pain. Your vet can provide pain medication, probably a pain patch with opiates that will stick on a small shaved patch of skin. Usually you need to put a new patch on a new spot every three days or so. Anti-inflammatories are dangerous and may not help anyway, but your vet would know best how to manage the pain based on what is causing it. Some oral steroids may help with the swelling and increase appetite. During this time, you can make plans and let people come say good bye. Give him his favorite foods and treats, let him lay in the sun, etc, and do his favorite things.

I agree it is not good to put an old animal through a lot of painful technology, and is better to let them go and respect their better, stronger self. If a simple amputation would relieve the cancer pain, then that would not be so bad, and I probably would do it, but skip the chemo. Dogs do fine with amputations, but at his age he probably has more complications and you need to focus on his comfort.

I recommend sedating before euthanizing. It is easier for both of you.