Very sick dog

This is Tron and he is very weak, suffering from acute anemia probably caused by something deeper and terminal. (maybe know tomorrow) Strangely he was running around the forest for several hours just a week ago and even three days ago he seemed fit. Oldish (12) but still very robust. Then bang it all seemed to end. He still moves about but seems very vulnerable and lost. All his life he was the most robust but calm dog I've ever known. It's a bit of a shock but as with Daisy his mother who died last year he had a very good life and always seemed to know it. Maybe he'll rally.