cat eliminates inappropriately while owners are away on vacation...

My cat Marvin is usually very good about using his litter box properly and rarely ever goes anywhere he isn't supposed to. Except for recently...we left him alone for about five days (which is the longest amount of time he has been alone) but had our neighbours check in on him every evening so he wasn't lonely. When we returned, we found he had used the bed as his litter box.
I am guessing that this was his way of expressing his disapproval of us being gone so long but I can't be sure. Has this ever happened to anyone else? Is there anything that can be done to prevent it the next time we have to go away?
Thanks!
Carolyn

Take your cat to the vet. When their routine is disrupted they can and do get stressed, stress causes illness and cats that pee on the bed do indeed most of the time turn out to be ill.

I think that your cat did not want to be alone for such long time. It may be some kind of revange, he was hurt that you weren't there. I did no leave my cat so long alone, may be she would do the same.