We have a problem with our cat which, apart from everything else, is a little embarassing. He is about 2 1/2 years old and we have started noticing small pellets of pooh here and there around the house every now and then. They are about the size of a rabbit dropping and initially we thought it was a blob of mud but now we're sure it's coming from him. He and his sister have a litter tray permanently available which they do use particularly at this time of year as the catflap is locked from dusk till dawn to keep them in. Cats are normally so clean and we've owned cats for many years but never had anything like this before. Any ideas anybody?