At Farplace Animal Rescue in Co Durham we have several older cats (10 years plus) who are desperate for new homes. Mostly, these golden oldies are ones who's owners have died. They are in good health, generally fully vaccinated and neutered, and sometimes microchipped.
Occasionally we have old cats dumped on us for some feable excuse, simply because the owners cant or wont cope with the needs of an older can and want to get a younger model instead.
5 of our older cats are causing me some concern just now. Sally (age unknown, but "old") was left in her dead owner's home for a month after the death. Since she has been with us she escaped (volunteeer let her out!) and was missing for a month. When we got her back, she had been living under the floorboards and was emaciated. She is slowly gaining weight, but cries constantly.
Chloe and Tess are 10+ years old and came to us when their owner died. They were house cats and had never been parted from her. They are very stressed and growl at everyone. Lillian and Ethel came to us because they "don't like the family dogs". Lillian is underweight, but has started eating. Ethel attacks everyone who comes near to her.
We use feliway plug-ins to help the cats settle, along with flower remedies for stress and seperation anxiety. We have also found that music helps too (they seem to like Mozart). Other ideas are always welcome.