My almost 1 year old male orange tabby has a swollen lower lip. It has gotten worse over the last 2 days. I will take him to the vet, however I haven't yet and was wondering if anyone has opinions. It looks serious to me but I don't know if I am over obsessing. He eats Friskies wet food 2x daily and 9Lives dry food. We have 2 medium sized dogs that he plays with but they are all very gentle together so I do not think it is a wound from them. He is an indoor cat but occasionally gets to go outside and walk around with the dogs when I am watching him, but he gets scared and is never out for more than a few minutes. Other than that he is indoor only, so I also do not think it is a bug bite or sting. Opinions?
PICTURES: http://web.mac.com/cnparadiso/iWeb/Site/Photos.html

Abscess, allergy, rodent ulcer (unrelated to rodents)?

Definitely take him into see the vet. Only the vet will be able to see you and your cat in person to assess what is really wrong with him.

My kitten has the SAME issue. It's happened twice. The vet is puzzled by it. We are giving her antibiotics for it now to ward off any bacteria infection. Next steps would be to try changing food (maybe it's a food allergy) or do a biopsy on her lip to check the cells. If you get any information, please share as we are trying to find answers right now as well.

Thanks!

My little ginger tom has exactly same problem, appeared only a few days ago :( did you get to the bottom of the problem? Xx

@hazy22 yes it turned out to be a yellow jacket bite/sting. He got outside and tried to play with the bee and got bitten. His lip healed completely on it's own in about 5 days. Good luck with your cat though! Hope it's the same thing.

Hi. My case was a bit different, but I know how stressful it was, so I thought I'd give you my answer as well. Our kitten's lip looked similar to the photos above, but it ended up looking more like a scab after a few days on her swollen bottom lip. We took her to the vet who suggested we switch to Prescription Diet d/d Venison and Green Pea which we did a couple of months ago. The blister healed up with the aid of a steroid, and she has not had any other infections since we changed to special diet food. It seems that food allergies to chicken and fish is actually fairly common and often show up as mouth irritations (like a Rodent Ulcer). Good luck!