My little dog is 16 and two months. Her heart is straining to pump the oxygen she needs and her lungs are bubbling and crackling with fluid overload. Still her eyes are bright and full of expectation. And in her sleep all four legs kick out in synchronised jerks as she runs like the wind in her dreams. I trace her outline - her boney head, the cleft where her shoulder blades meet, the curve of her ribs - like someone who is losing sight of our shared future.