It really hurts when we lose our best friends, I am very sorry to hear of your loss. I have no words to comfort you,but do know you will forever be in her heart too.
You did nothing wrong,it's not your fault,that's a common thing we feel when we have no answers to what and why something bad happens to them, after all we are "dog moms" and they are our children with fur.
I have a plaque that says "dogs leave footprints on our hearts".
Yes, certain cancerous tumors can grown quickly, stillborns can happen too, but there was no way you knew what it was, a vet may have been of help, but again quick growing tumors are quick killers, in my life we lost a few dogs to a certain cancer, I think it is called hemangioma carcinoma (can't remember exact term) which attacks the organs quickly. It is extrememly sad. Breast (mammary) cancer can occur too, spaying a ***** at a young age decreases her chances of developing that, a ***** should be spayed if she is not going to be used for breeding, for so many reasons
Males should be neutered for the same.
No sense of putting them at any additional risks,or unwanted pregnancies, everyday more and more dogs and cats are euthanized, I've witnessed that in domestics and the raptor and wildlife center, it is heart wrenching.
Never feel spaying/neutering is mean, and it doesn't change the dog's behaviour, that's all hogwash.
Sorry, off topic, I apologize.
Rhap, my heart goes out to you, us animal lovers can understand how much we feel about our pets.
Animals do miss their loss, we had several pets that seemed to mourn. It is important and I know you'll do this, give them comfort,extra attention for a little while, you can all console one another,not even realizing it.
I'm sending you well wishes for strength,healing and hope.
Please take care now,
DE

(((((((( Rhapsody and family ))))))))))))