our jrt always seems to be hungry and has lost a lot of weight. we can't feed him enough but he never puts weight on. he is 14 years old now. he usually looks fed up but sometimes acts like an excited puppy fetching toys etc etc. he's always drinking water especially stale rainwater in drains and bird baths and its a constant battle to stop him drinking this dirty water. the vet wants us to spend £100's pounds on tests but from what they say, he has a liver problem and they want us to spend a fortune on a diet and tablets supplied by them. any advice for our human trapped in a jrt body?