What this means
The inside of a healthy cat's ear is pale pink, dry and almost odourless. Stronger redness, warmer skin, a thickened ear flap or swelling on one side is a change worth noting. Look at whether only the inner surface is red or the opening of the canal too, whether one ear looks thicker than the other, and whether there is discharge, scabbing or a smell.
Cats can scratch and shake their heads hard, so redness is sometimes partly the result of the scratching itself: scratches, scabs and a swollen ear flap from the knocks. In that case the original cause is an itch or pain rather than the redness, and the vet has to find out what is driving it.
Cats hide pain, so the only hint of an ear problem may be small things: shaking the head more, flinching when the ear is touched, becoming irritable or holding the head slightly crooked. If you also see unsteadiness or a head tilt, it is no longer only a question of the ear flap.
Possible causes
These are things that can cause this sign. It is not a diagnosis, and they are not equally likely for your cat.
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Inflammation of the outer ear canal
The skin of the canal reddens and swells, and there may be discharge and a smell. The cat shakes its head and scratches the ear.
About the condition: Ear infections -
Ear mites or other parasites
They cause a strong itch, and scratching reddens the skin. Both ears are often affected, especially in a cat that lives with other animals.
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Allergy
An allergic reaction can redden both ears, and other parts of the body may itch as well.
About the condition: Food and seasonal allergies -
A blood blister in the ear flap
Hard shaking or scratching can let blood collect in the flap, so the whole flap swells and thickens.
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An injury or bite
After a fight or a scratch the ear can redden, swell and hurt. The wound may be hidden under the fur.
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A foreign object in the ear
A grass seed or other small object irritates the skin, and the ear reddens while the cat suddenly shakes its head.
What else to watch for
These observations help your vet build the picture faster. Note down what you saw and when.
- Whether one ear is red or both
- Whether the ear feels warmer and thicker than the other
- Whether there is dark discharge, scabbing or an unpleasant smell
- Whether your cat shakes its head, scratches or avoids being touched
- Whether there are scratches or small wounds around the ear
- Whether your cat holds its head crooked or is unsteady
When to book a routine visit
Book a visit if an ear is red or swollen, or your cat scratches or shakes its head. Do not wait for it to pass by itself: ear pain can sit deeper than you can see. If your cat tilts its head or is unsteady, go the same day.
Related conditions
Conditions whose entries mention this sign. The list is somewhere to read on, not a way to reach a diagnosis.
- Ear infections Ears and hearing Inflammation of the ear canal, in which bacteria, yeast or ear mites take hold and make the ear sore and itchy. It matters because a long-lasting infection can reach deeper parts of the ear and affect hearing and balance.
- Ear mites Parasites Microscopic mites that live in the ear canal and feed on the skin's surface and earwax. They cause intense itching and spread easily between cats, dogs and other animals.
Body systems: Ears and hearing Parasites