SAS,

I'm sorry you couldn't get a more definite answer from the vet. But as with all outdoor kitties, they have a certain exposure to the "elements", whatever they may be. You should NOT blame yourself. There are alot of chemicals outside. People have their lawns sprayed with insecticides. Those become airborne and can infect the lungs of not only animals, but humans too. Look at all the people that become sick. I believe it has alot to do with the environment. It sucks.

You have my sincere condolences on the loss of Graemer and Gabe. I hope Miley is okay. Hang in there.