Personally, I dont really prefer the option of euthanasia since it feels like ending life prematurely... If your dog time is up, i don't think euthanasia is gonna shorten the time by alot. Instead, I think you could spend more time beside your dog and give it much love and comfort until it pass naturally... As for cremation, you can google it as there's quite a few pet cremation company out there.They will usually provide door-to-door service to collect your pet's body, some even accept the requst to allow owner to witness the cremation(if u want to) Usually after cremation, the company will offer you the option of having the ash put into the ocean or sending it back to you in an urn. It must be a hard time for you, stay strong though!!