Cat missing inside house

I have 12 indoor only rescue cats and one dog. I have been dog sitting for my son's dog for the past 10 days. The cats all like my dog, but are afraid of my son's dog because she chases them. My son's dog is very friendly, but a little over curious about the cats. When the dog first got here, most of the cats (including Aslan, the missing one) went straight to the basement and are still there. After 5 days, Aslan went missing and is nowhere to be found. He is not coming out for wet food in the evening as is our routine. I am almost certain he did not get out of the house, but cannot locate him ANYWHERE in the house. I have looked between walls, in the drop ceiling, under appliances and furniture and have not been able to find him. Also, I have never heard this cat make a sound. I am afraid he is trapped somewhere in my house and either can't or won't make any noises to let me know where he is. I have not seen him for 5 days and am worried sick. Please, I would welcome any advice. Thanks!

I would suggest putting the dogs in a single room with the door closed or getting a dog crate and crating your son's dog at night.  Then you can leave out food and water in several places that Aslan might find it.  He is probably sneaking out when the house is quiet, but if there is no food or water to be had, he could very well get sick.  Since the dog has already chased the poor cat, he is unlikely to come out.  Even though your dogs were OK with him, now he has experienced the OTHER side of "dog" he is not going to take any chances.  I hope your son's dog will be going home soon and that Aslan will rejoin the family.

@ Red Top Rescue, thank you so much for your reply!  So you know, most of the cats are keeping to the basement (except like you said, when it's quiet) so I have dry food and water available down there at all times. If I understand you correctly, he is probably hiding because the dog chased him and most likely will stay hidden until the dog is gone. I guess this is not unusual behavior? My big concern was that he was stuck somewhere. If that was the case, and he doesn't cry out, he would at least make some noise trying to free himself, wouldn't he? I am somewhat relieved by your reply and very much appreciate you taking the time to respond.