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My cat has a growing lump on his side and can't jump well. What is it?

Updated On September 23rd, 2025

Pet's info: Cat | Mixed Breed | Male | unneutered | 1 year and 8 months old

My male cat that is over a year old and also inbred if that matters. He has stayed fairly small in size. I noticed a lump on his side a day or 2 ago and now it seems to be growing larger. It doesn't seem to bother him and there is no drainage of any kind. It seems as though he can't jump very well. He had a hard time just getting on my bed and sometimes he'll give up and walk away. He's had a UTI in the past and I gave him his antibiotics for that. That was a few months ago. I'm really worried.

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1 Answer

Most Helpful Answer

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Answered By Dr. Melanie, BVSc MS

Veterinarian

Published on October 9th, 2017

I can understand being worried about TJ! I can see the lump from the picture you provided, and I have a few ideas as to what it may be. I see that he's not neutered, and intact males will frequently fight with other males for territory and females. If he's allowed outside, he could have gotten into a fight with another male, and developed an abscess from a cat bite. A cat's mouth has a lot of nasty bacteria in it, and abscesses are a common sequela to a cat bite. Abscesses are painful, so that may be why he's having trouble jumping on the bed. He could also have a cyst. Given that this lump is getting larger and he's having trouble getting onto your bed, I feel a vet visit in the morning is in order. The vet can diagnose what is causing the lump and how best to treat it. If he does have an abscess, it will need to be drained and flushed, and he will need antibiotics to treat the infection. I hope this helps!

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