I had almost forgotten exchanging messages with you back in 2010, but have been sorting emails, and found the notification of your response.
I thought you might be interested to know that the problem with the cats turned out to be Tritrichomonas foetus, brought into our cattery by a kitten that we had been given as a neutered pet in the October. We didn't realise immediately what the problem was, but continued to have bouts of some of the cats being off their food and/or having diarrhoea until we identified the problem and treated them all with Ronidazole. Since getting the all-clear a year past in December, we have had no further problems of this nature.