My experiences of swellings in cats relate almost exclusively to head and neck abscesses (opens new window). On a few occasions I have tended to abscesses in a stray cat that I used to look after. Head abscesses appear quickly and the cat can also be feverish. They are very tender and painful. For some cats opening the mouth can cause extreme pain. These cats won’t eat or drink.
Feline abscesses are often on the ear or back of the head causing quite pronounced swelling due to pus below the skin which is caused by a bacterial infection which in turn is often caused by a bite from another cat. Sometimes sharp foreign bodies can be embedded in soft tissue causing infections.
An abscess in the frontal sinus can cause swelling beneath the eye. Submandibular abscesses cause swelling beneath the chin. An abscess behind the eye causes protrusion of the eye.
I have mentioned an abscess in the ear flap but swelling can also be caused by a haematoma which is a blood clot under the skin of the ear. Haematomas of the ear can be caused by trauma or even by violent head shaking and scratching at the ear which in turn may be due to a parasite.
A swollen head might be due to an allergic reaction. Sudden swelling of the face, lips and eyelids can be caused by a “hive-like” allergic reaction. It is called urticaria. The head of the cat may be strangely out of proportion to her body with swollen, shut eyes. The allergic reaction is commonly caused by insect stings, allergies inhaled, contact allergies and food allergies.
Feet and legs can be injured leading to swelling. The swelling is probably due to a bacterial infection. A vet will no doubt irrigate the wound to remove dirt and bacteria. Swollen paws are often caused by a foreign body such as a sharp object stuck in the paw. Sometimes an overlong claw may have pierced the paw pad causing infection and swelling.
Other causes of facial swelling might be: dental abscess, tumour, fungal infection or paracetamol toxicity. A fungal infection called cryptococcosis results in hard, nodular swellings over the nose. Paracetamol toxicity causes accumulation of fluid in the face resulting in swelling.
Conjunctivitis (pink eye) causes swelling around the eyes. Foreign bodies such as grass seed getting into the eye can also cause swelling around the eyes.
A sarcoma (a cancer), perhaps due to a vaccination can cause swelling in that area. In addition, vaccination injections can cause an inflammatory response at the location causing a small lump. It will normally go away but it can lead to “injection site sarcoma”.
As for the cat’s belly an obvious cause of swelling there would be pregnancy, other causes might be worms, fluid buildup (ascites), intestine blockage, constipation, ruptured bladder and pyometra. Pyometra is a secondary bacterial infection caused by a uterine infection which in turn begins with a disease called cystic endometrial hyperplasia. Pus builds up in the cavity of the uterus. It is a life-threatening infection that occurs most often in breeding cats over 5 years of age. The cat will have a fever, be lethargic and refuse to eat.
Fluid buildup in the belly of a cat may be caused by a range of illnesses such as: feline infectious peritonitis (FIP), heart disease or cancer.
An anal sac abscess is an infection which causes swelling at the site of the gland. Initially, the swelling is red in colour. Then it turns to purple. The cat may have a fever. The cat may lick at the area more than usual.