Short answer: often normal, but have it checked
A lump at or under a cat’s spay incision is often part of normal healing, but sometimes it points to a complication. You cannot reliably tell the difference by touch alone, so if you are unsure, call your veterinarian. Take note of when it appeared, how big it is, and how it feels, which will help your vet.
Common causes
Seroma. A seroma is a pocket of fluid that collects under the skin. It tends to feel soft or squishy, and it is not usually hot or painful. It is more likely if a cat has been too active during recovery.
Suture reaction. The body can react to internal stitches, producing a small firm bump. Many are mild, but some need treatment, so your vet should look at it.
Scar tissue and normal swelling. A firm ridge along the incision is a common part of healing and often flattens gradually over the following weeks.
Do seromas go away?
Many small seromas are reabsorbed by the body over a period of days to weeks, particularly when activity is restricted. A seroma that is large, growing, painful, or not improving should be examined. Vets may monitor, drain, or treat it. Do not try to squeeze or drain it at home, because that can introduce infection.
What a hernia can look like
An incisional hernia occurs when tissue from inside the abdomen pushes through the muscle layer beneath the incision. It may look like a soft or firm bulge that can change size, may be more obvious when your cat is standing or straining, and may or may not be painful. Hernias can range from minor to serious. Any bulge that grows, feels hard and painful, or comes with vomiting or lethargy needs prompt veterinary attention.
Signs of infection or a bad incision
Contact your vet if you see:
- Pus, thick or colored discharge, or a bad smell
- Spreading redness, heat, or significant swelling
- An opening in the incision
- A lump that grows quickly
- Pain when the area is touched
- Lethargy, fever, or not eating
To compare against normal healing, see what a healthy spay incision looks like.
What to do at home
- Keep your cat from licking, with a cone or recovery suit
- Limit running and jumping
- Do not press on, squeeze or massage the lump
- Do not apply creams, heat or home remedies unless your vet advises it (see what not to put on a cat wound)
- Photograph the lump daily next to a coin or ruler to track changes
What your vet may do
Your vet will examine the area and may simply recommend watching and resting her. Other options can include sampling fluid, medication, a recheck, or, in some cases, surgery to repair a hernia or clear an abscess. Which option is suitable depends on the exam.
When to call the vet
Do not wait if the lump is growing, hard, hot, painful, draining, or accompanied by changes in appetite or energy. If the lump is small and soft and your cat seems well, a call to your clinic is still reasonable, and they can advise whether to bring her in. A lump that appears long after healing, or does not go away within a few weeks, should also be examined.
Related guides
This article is general information and not a substitute for advice from your own veterinarian.