>Thought he was a bit too young to be showing signs of ageing at this stage
Hi, it's quite easy to miss a gradual decline. I did just that with my terrier type mongrel and, like you, assumed some of it was down to age, but also the contrast effect with the arrival into our lives of a bouncy puppy. Thinking back I can pinpoint a particular incident which was vet checked at the time but which may have started it. My boy experienced a very slow deterioration (3 years) and then he had a rapid onset emergency.
Luckily he pulled through, with great vet support and surgery but I spent quite a while kicking myself for not pursuing it earlier. Hindsight is a wonderful thing...
I won't alarm you with the full drama of our story as it was a pretty unusual case but before you go to the vet have a good think about when you first noticed signs. Be as specific as you can about what you've noticed and how it contrasts with earlier behaviours. As owners we are in the best place to realise something is 'off'. Give the vet a written list if you're not sure you will remember it all and cover things like eating, drinking, toiletting, coughing, sickness etc, as well as general exercise and sleeping habits.
Be prepared for analysis to take a little while, vague symptoms can sometimes be a bit tricky for vets to get a handle on but do persevere if you are concerned. Fingers crossed for you xxx