The ups and downs of dog fostering

Ruby has been chipped, the vet thought she was actually about a year old and also thought that she is a cross between border collie, not a briard but something smaller and she is probably fully grown. The very bad news is that she has a heart condition. We noticed in the very hot weather that she quickly finds the coolest spot and that she tires easily after boisterous playing. The vet has given some medication as a trial and thinks she could have a reasonably long life with the right people. She would need a fenced garden, shade and small walks not in the heat of the day.
We are all very upset, as her chances of finding a home have just lengthened. We would keep her as she is adorable and manageable but she does chase the cats and I cannot bear that they have left home.
Is it a big ask to take on Ruby, it would need someone with a big heart but  I am sure there must be someone who fits that description.
Contact me if you would like to know more of dear Ruby
A vet friend who is coming up to seventy said to me, " Val I have had a heart murmur since I was tiny"
Kind hearts to Val at  taglines82@gmail.com