im sorry for you but he a happy dog now with no pain,we to lost our great dane but early last year with Heart Failure.He was 10 years old and will always be in our hearts. Then we had another blow and lost out Dogue De Bordeaux to cancer,she only had 2 weeks to live without chemo or she had 3 months with.We let her go peacefully without the chemo and no pain.
Time is a great healer i feel for you:(