One of the issues with senior food is that it has less calories. So if Tigger isn't overweight you don't have to switch him.

But regarding the teeth you may have to see the vet for toothcleaning. You can check whether the gingiva are red or even bleeding. Tooth cleaning means anesthesia and it's a bit expensive but if you don't do it Tigger might be in pain and lose teeth. It works very well and they recover from the anesthesia in no time.

Filou has had it three times up to now. Catdad's Bob and Joey are just through their first time. It depends not only on food but also on the chemistry of the saliva (as it is with humans) so if you have not one of the extremely rare cats who allow you to brush their teeth there is not much you can do


five minutes later: oh I just checked Tigger out. He's gorgeous and with 6 he's too young for senior food but the night of starving before the tooth cleaning can not really harm him