We have a Norwegian Forest cat who has always been on the skinny side of OK. He will be 9 in April.
He's always had a, er, delicate digestion. He's been on a variety of diets (started on James Wellbeloved kitten, then moved to Royal Canin Kitten, from that, he's been on RC Maine Coon, RC Exigent and RC Hair & Beauty and when his tummy got looser recently, we moved him onto Arden Grange Sensitive). Wet food upsets his tummy even more.
Took him to the vets a couple of weeks ago, who prescribed a course of antibiotics which did nothing. We then wormed with 3 days of Panacur which have also done nothing (he is wormed yearly with Drontal anyway, doesn't go outside, only mixes with our one other cat and has never had fleas so 'low risk' for being wormy). An internet search showed that he ticked every single box for hyperthyroidism, took him to a different vet (same practice) who agreed it sounded like his thyroid but did a general blood test rather than a specific thyroid one - just in case the thyroid came back as normal.
Results were back today - vet rang with 'good news and bad news'. Good news is that bloods say there is nothing wrong with him - everything is slap bang in the middle of OK/normal. Bad news is that bloods say there's nothing wrong with him - so no idea what to do now. Vets suggestion when asked what he would do if it was his cat was to say he'd try a different food again. He's well in himself, he plays, he has a lovely coat etc.... He's just too thin.
What would you try next if he was yours?