newly adopted cat hiding/not eating

Question
I adopted two cats from the Animal Welfare League 3 days ago. They were siblings and one was male, one female both "fixed". The male seems to have a cold or something, he keeps sneezing, sounds hoearse when meowing and refuses food, will only drink when i come to him and hold it under his face and sit with him while he drinks. The female really concerns me as I have seen her only once in the house. She ran from her crate to the closet and from the closet to the basement the very first day. My husband finally spotted her in under the basement stairs. They are enclosed and there is a very narrow space that she had to have really struggled to get through. I can't see her there today and I am worried she went deeper in between the walls or something and I am especially concerned that while I have left a litter box, food and water it remains untouched. I know I must get them to the vet, but how can I lure her out? Is this normal? My husband is going to tear a stair out to try to locate her and if not I guess we will tear the wall around there. I am scared. I had a cat previously and he was my companion for 10 years before he passed, I waited another 10 before falling in love with these two and don't want anything to happen to them. Please help!

Answer
Aw, sorry you're going through such a hard time, Nell.  I guess the male is easy enough to catch, and you're right - definitely time to see a vet.  Try to get this done before the weekend, as serious complications like dehydration and Fatty Liver Disease (potentially deadly liver failure) can set in from not eating for 48 hours or longer.

As for the female, really the best I could say to do if you can't get your hands on her is see about borrowing a live trap from your animal officer or shelter, and set that up where you saw her last, with tuna as the bait.

Once you've got both of them, I'd keep them confined to a small area such as a den or small bedroom, even a bathroom.  Cats feel much safer in small areas, so I always recommend that they be limited to one small room for the first week or so in their new home so they don't become overwhelmed and hide.  Some take longer than that.  Once they are comfortable enough that they're eating, using the litter box normally and seeking attention, then you can allow them out to explore the rest of the home.