I have seen 2 seemingly healthy trees fall victim to borers. One a Sycamore about 6 inches in caliper, it was planted as a whip. It had a v shape I got rid of one side of the V, hoping for a 1 leader tree. The borers attacked the pruning site where I got rid of the other side of the V. The other was my mom's large Tulip tree (liriodendron tulipfera) Missplelled I know. It was 3 ft diameter at least. Borers attacked the lower trunk, where I would bet if I had money, my dad ran into it with the tractor. This happened before I was the primary grass cutter of the family, so i am off the hook. So both of these things in my yard, I can guess there was injury or at least stress involved. But with the Dutch Elm thing, that happened to many likely not injured or stressed trees. I just think or darn well hope that there must be the situation where most trees aren't dying when there is no previous problem. But not to get into a whole "messy thing" but healthy people can get Ebola if exposed. This is a tool to get my point across ONLY. I know nothing specific about that whole mess. But, I had figured that the bugs were natures cleanup crew, and good wood would not fall prey to disease and/or insects unless there was/is an underlying problem that is just how nature is. There are some surviving Dutch Elms (or Elms) in the UK according to a book I have. The disease never reached those few trees.

So far we love our Marvin slider. As spring progresses we've found we can't open it as much - too many bugs! It needed some adjustment at the beginning. A rep came out and adjusted it no problem. Marvin has been fabulous! We have a set of two very tall French doors in another room. After they were installed last fall they were fine. Then we got a lot of rain. Slowly the bottom of one swelled and started hitting the bottom of the other and eventually we couldn't open the door. The Marvin person came, saw the problem, and ordered us a whole new set of doors about 1/8" narrower (these are very expensive doors). When he came back to install them (a few months later due mostly to us) the original doors were fine. He said he thought that might happen (companies use very green wood to make doors so they may take some time to get to their proper size). He left the new doors with us - so we have a spare in case something happens to the others. So far the same person has come back to do all the servicing. He's from Marvin itself. (The contractor also has the store that sold us the windows as a back-up but so far we haven't needed them). He's great - fixed a couple of other small problems. I really feel like they stand behind their products. We're having a lot of problems with our Miele appliances - their service is supposedly great but there's no comparison. Miele is a total pain, Marvin is a total pleasure.

You may want to just keep the sliders and add screens if you want the cats to stay inside. I have Pella sliders with a screen that's on the interior side of the sliding door and I consider it perfect for use with pets. It can be latched/locked so there's no chance my cat can get outside. Since your cats are indoor/outdoor now, consider doing what holly mentioned. My cat has a cat door in the BR that opens to a wire tunnel. The tunnel then leads to a 10', six ft. high kennel that sits in the corner of the deck. Makes for a happy cat..........

I am Doug the Screen guy the owner of Screen Solutions Inc the maker of the Plisse screen. While we can never guarantee a pet will not find a way to get under our screens we have had good results lots of customers. Some customers have contacted us after the purchase having problems with their cats and we have been able to help them figure a way to make the Plisse secure. If judander contacts us we may be able to help. Here is a link that might be useful: Plissescreen