
So very very sorry
Cancers can go so quickly & dogs are stoical, they rarely show pain when they are hit by internal cancers. Our GSD Echo was apparently fit & well, went to the vets for a booster(back in the days when I still did them)he cried when the vet was giving him a quick once over & a huge mass was found on his liver & the cancer was throughout his body They let him go under the GA
There would have been nothing you could have done
Cyber {{{{{HUGS}}}}} to you