My cat is eating more, losing weight and his fur looks like hell

[TrogL]

Also, his anus is reddened. Other than that he's behaving normally.

Other than the obvious "take him to a vet", any ideas what's going on?

[Granny M]

1. How old is the cat?

I'm no expert, but I lost my 13 year old cat a few years ago to renal failure. His coat looked horrible for weeks. I don't recall any abnormalities with his anus. His appetite stayed normal. I think it's worth taking yours to the vet. It could be something serious and early treatment could help.

[TrogL]

2. Probably around 12

[KC]

15. Is he

having diarrhea?
Maybe he has worms ?

[DeltaLitProf]

3. So many likely possibilities

. . . but especially diabetes. Does he drink a lot of water?

[Freddie]

4. Thyroid problem

Very common in older cats. Eats a lot but still loses weight, often frequent vomiting. Take him to your vet. If its thyroid it's easily diagnosed by a blood test and you'll have to give him pills but the treatment will bring him back to good health. Best of luck!

[rox63]

5. Classic symptoms of thyroid disorder

It can be treated and stabilized with medication.

[siligut]

6. Because his anus is inflamed, I would suspect that the rest of his lower GI tract is too

What do his stools look like?

[TrogL]

9. Can't tell about a lot of stuff

He's an outdoor cat so can't get a stool sample. There are multiple cats in the house so impossible to sort out which is his. Haven't noticed him hogging the water fountain, but it's been raining a lot and there's plenty of puddles outside.

[siligut]

10. Since he is an outdoor cat, maybe worms

Do you see anything like specks of white near his anus?

[TrogL]

11. Haven't been looking specifically for that, but so far no

[siligut]

12. Well, he isn't getting the nutrients from what he eats

So maybe the worms are eating his food. Or, due to inflammation, food is passing through without being absorbed. Or as others have said, diabetes could cause weight-loss, but you would see increased thirst. I hope you figure it out and kitty gets better

[sinkingfeeling]

7. Thyroid, cancer, or diabetes.

[ginnyinWI]

8. Renal failure?

If not that, then diabetes. I think in both cases they drink a lot of water.

I've had cats with both renal failure and overactive thyroid. The latter can be treated with a daily pill. But renal failure is much harder--they don't like the diet, usually, so it's just a matter of keeping them comfortable.

[Curmudgeoness]

13. I hope that it is not renal failure, but if it is,

since you mention food, the only brand that my cat would touch was Royal Canin, and that was after trying the Science Diet and Purina prescriptions.

[KC]

16. Royal Canin

is the only dry cat food that's me can
eat and not throw up! He loves it too.

[Curmudgeoness]

14. My first thought was thyroid problems,

which are treatable and easy to diagnose with a blood test. But after reading the other comments, I am more inclined to think worms. I had a cat with hyperthyroidism, which is common in cats, and all the symptoms you mentioned were present except any problem with his anus.

If you really want to get a stool sample for a simple test for worms, just isolate this cat in a room with a litter box until you get one. It may not be convenient, but it will make a diagnosis so easy if it is worms.