Parrot and Cat
if your cat is getting on in age and his joints are starting to stiffen up then there are things that you can do to help him besides vetrinary treatment.
A good homoepathic treament to give him would be Rhus Tox .This is especially good for athritis which gets worst in cold and damp weather.You can get it from homoepathic companies or even from high st shops such as Boots. It should be given twice daily and it should be given in the 12c potency. You can get it in tablet or liquid form . Use which ever you find easiest to give your cat.
I don't know if cats purr when they are alone. It seems likely that they do, if one understands a little about why cats purr.
Most experienced "cat wranglers" now know that cats don't purr only when they are content and happy. They also purr during tense or traumatic moments. When suddenly and violently injured, even at moments near death, a cat will often purr. I've often likened this to saying, "Please don't hurt me any more. I'll be good," but recent studies have put a more scientific spin on this seeming anomaly.