16 yr old welsh keeping weight/losing weight

[throughtheforest]

I am very pleased to say even with his heart condition and copd diagnosed when he was 3, our much loved pony has made to being 16! Just a few things that i would like some advice on.
He is keeping weight on unusually well with fatty deposits, not being fed anything other than good meadow grazing which is in no means lush and he has been on this all year so why the weight increase now? Personally I think it could be metabolic which im happy to supplement, however during the winter he usually loses condition and has some sort of virus around March time coupled with mud fever which i am of the opinion that this points to low immunity. He will be well rugged as usual with adlib hay, but if anyone could suggest any advice or feed recommendations i would be grateful

 

[_HP_]

Fat pads would indicate a metabolic issue like EMS which is treated by keeping weight down .
This is the prime time of year to see sudden weight gain so I'd maybe restrict grazing for a while.
Skin problems, weight loss, virus etc can all be symptoms of PPID (Cushings) and considering his age also, I would perhaps ask your vet to take advantage of the free test
http://www.talkaboutlaminitis.co.uk/certificate-form/

Have a read of this site and maybe join their forum or Facebook group for some great advice
http://www.thelaminitissite.org/ppid.html