Oh Ali I am so so sorry to hear about poor Maddie. We know what your going through, we lost our first Munster Baron at the same age to the same horrible disease. It was a very traumatic time as the vet tried everything but didn't find out what it was for a few weeks until he finally had to operate and found the tumor.
Merlin our spaniel also didn't want to go for a walk for weeks after. Animals do know or sense something don't they, Mums cat (who lives next door) spent the week after he died sleeping on his bed which she had never done before.
She will leave a big hole in your lives as did Baron but as a result of loosing him we were in contact with you and now have Jed and Elva which we are thankful for. Thinking of you all at this sad time.
Sarah x