Wendy,
I'm so sorry to hear about your sweet little Dixie. I hope you will soon be able to find comfort in your memories of her and the fact she is no longer suffering and is watching over you and your family now.
I lost my bullmastiff to lymphoma just over a year ago. I was lucky enough to give him two more GOOD years with chemo before we had to let him go.
It's so hard to understand how these innocent little creatures end up with such a horrifying disease. I can't imagine trying to explain it to your children. You are all in my thoughts and prayers.
Rest in peace little Dixie.