Old cat digestive problems

I have a 14 year old, almost 15 year old Gray American Shorthair cat. Although he seems to be a little sore in his back end, he is quite active, despite being obese. He plays with our 1 year old cat Oliver for hours, and even wins the battles even though Oliver is bigger and younger.

Anyway, my question;
I have noticed that he has stool around his bottom end... and it's been that way for at least 3 or 4 days. It's very runny and has apparently dried there. I whiped it down today with a warm paper towel and at least cleaned the opening.

However, I came home 20 minutes ago to find he's all dirtied up again.

What's going on? Is he sick? Should I take him to a vet? Does he need to switch food (He is on Iams... regular formula in the orange bag, as all of our cats are different ages and feeding them all different foods is hard to do)

Something else wrong here?

Thanks,
Jason

I would take him to the vet to rule out any major problems. than perhaps look into the food at the culprite. I know One of my girls got a bit of runny stuff once ina while (not as bad as your saying) than i started mixing bil jac in with their usual food. and we havent had a problem.

First take kity to the vet ... he needs at least a senior panel ... second give all kitties senior food ( I dont like Iams but if you do get the burgandy senior one) as long as the youngest is over a year ,,,

You mention he is obese. It is possible that he can't reach around to clean himself and that is why he is dirty. But because of his age, if you haven't had a senior panel drawn, it would be a good idea to do so. Just so you know if anything is going haywire inside.

Does he have long fur around his bum? He may need a trim

He does not have long hair around his bum.

His anus looked somewhat irritated (as would be expected from it being soiled all the time )

I will take him into the vet..

What exactly is a senior panel? A checkup for an old cat?
As for being obese, has has actually lost weight during the last year due to the introduction of our "kitten" who is now a year old. He keeps rascal busy and excercising.

A senior panel is a blood test that checks a variety of things, including thyroid, blood sugar levels, and kidney function. It is a very good idea to have this done on older cats because it can help you catch problems early while they are easily treated. While you are at the vet's office, mention his weight loss (thyroid levels could be contributing) and the messiness around his butt. Have you noticed loose stools in the litterbox as well? You may want to ask the vet about adding a little bit of canned pumpkin to his food. It can help make the stool the right consistency. Sometimes older cats need a little help regulating their bowels, just like older humans, and the fiber and moisture in the pumpkin will help.