GENTLE WARNING: THE PICTURES ON THIS PAGE ARE A BIT OFF-PUTTING. There are 8 possible or potential causes of lumps underneath your cat’s skin. What comes to mind immediately are those nasty botfly larvae a.k.a. warbles, which live their lives under the skin of a host animal such as a cat with a little breathing hole. It conjures up a disgusting image in one’s mind. They are also called grubs or cuterebra. They are about an inch long and therefore cause a lump beneath the skin.
The reason why this parasite is possibly the most likely is the location of the lumps. This is a lump which may be felt typically beneath the chin, on the neck or along the abdomen. This would seem to make it the prime culprit.
Other potential culprit might be an abscess but these normally occur on heads because it’s where cats bite each other when fighting. If an abscess does form it is because bacteria has infected the cat under the skin causing a painful collection of pus at the site of the puncture wound. The swelling feels quite firm which becomes soft over time with a purulent discharge.
What about cancer? This is an ever present problem but I think it’s less likely than the first possibility or even the second.
Another possibility is an epidermal inclusion cyst which is a firm and smooth lump beneath the skin which may grow slowly and discharge a substance described as “cheesy material”. It may become infected but it is not painful.
Blood clots beneath the skin normally occur on the ear flaps caused by an injury and they may be painful. They are referred to as haematomas.
A fungus can cause mycetoma which is a nodule beneath the skin with an open tract to the surface draining a granular material.
Skin papilloma is a possibility as they grow out from the skin and look like warts or a piece of chewing gum stuck to the skin but they aren’t painful and neither are they dangerous.
Fungus also causes a condition called sporotrichosis which is also a nodule with overlying hair loss and a wet surface of pus at the site of a puncture wound or a breakage in the skin.
Sources: myself and books mainly Cat Owner’s Home Veterinary Handbook.
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