Petco Text Logo
Petco Pet Logo

Why is my cat losing weight and has a painful lump on its side?

Updated On September 23rd, 2025

Pet's info: Cat | Mixed Breed | Male | neutered | 6 years and 7 months old

My 6 year old cat Olliver has a hard lump on his left side that hurts him, he eats but doesn't gain weight, and seems to be getting skinnier. He has a sensitivity to hard or dry foods, he only can eat wet or soft. He doesn't like to be active, just sleeps a lot.

1 Answer

Most Helpful Answer

Image profile

Answered By Dr. Elizabeth

Veterinarian

Published on December 1st, 2017

I would be worried that Oliver has something going on that has the potential to be serious. Oliver needs to see the veterinarian ASAP for bloodwork and the check the mass and his teeth. Bad teeth, cancer, kidney or thyroid disease could all account for the weight issues. A painful mass does not always mean its cancer but you still need to be concerned. The doctor may recommend to aspirate the mass to determine what it is and what steps are most appropriate moving forward. I hope this helps!

Vote icon

2Pet Parents found this answer helpful

image
Have A Vet Question?

Book an appointment with the pros – our expert vets are here to help.

Sponsored