Any suggestions before I spend £40 + at the vet?
Boss is panting a lot and has very smelly breath. He is drinking more than usual.
Damian

Blow the £40 - just get him there!!  At 12 years old, that's less than a packet of cigarettes a week!

It could be his teeth - would you like to go around with toothache?   Or it might be the sign of an underlying heart problem - but with the excess drinking it does sound like diabetes :(

Margot

The symptoms fit heart problems, kidney problems, diabetes, dental problems ... only a vet can examine him and tell you for certain. The sooner the better, eh? Good luck.

Diabetes could be in there too - or a spleenic tumour which is pressing on the lungs or has metasised :(

£40 is nothing for peace of mind, honestly...