Protrusion of Third Eyelid in Cats

We humans also have a nictitating membrane, but this is much less pronounced than in our four-legged companions. The transparent nictitating membrane of cats is the conjunctiva in the corner of the eye on the nose. It protects the cat’s eye and contributes to its moistening. If the nictitating membrane falls forward and pushes itself into the eye, this impairs the view of the cat. Read here how to identify a prolapsed nictitating membrane in your cat and what you can do about it.

Symptoms: What is a Cat’s Nictitating Membrane Prolapse?

In healthy cats, the nictitating membrane, also known as the third eyelid, is barely visible. It is only recognizable as a small wrinkle on the edge of the eye near the nose. If the nictitating membrane has prolapsed, it becomes visible and covers parts of the cat’s eye. That is why even laypeople can easily recognize a nictitating membrane prolapse.

The nictitating membrane is often seen in sleeping cats – this is nothing to worry about. Sometimes the nictitating membrane is also clearly visible when the cat is tired or dozing. If this is bilateral and the cat does not show any symptoms of illness, it is also not an alarm signal. If you are unsure, speak to your vet at the next check-up.

Diagnosis: What is Behind a Cat’s Nictitating Membrane Prolapse?

A nictitating membrane prolapse is not a disease, but a symptom. This can be caused by various diseases.

This is why you should always see a veterinarian if you see the third eyelid popping into the eye.

If one eye is affected individually, the incident indicates a specific disease in that eye. In the case of a bilateral nictitating membrane prolapse, the general condition of the velvet paw is out of balance. This tends to be a sign of a whole-body disease.

Mostly one-sided: diseases of the eye

Conjunctivitis is often responsible for changes in the eye. Even minor injuries, for example from scuffling with other cats, can be behind the symptom. In rare cases, tumors are the cause of a nictitating membrane prolapse. Another possible cause of a prolapsed nictitating membrane is otitis media, which affects the nerves in the area around the eye. Neurological deficits occur, more precisely: Horner’s syndrome.

The Horner Syndrome

A one-sided nictitating membrane prolapse in combination with a sinking in of the eyeball and drooping of the upper eyelid speaks for the “Horner syndrome”. This is a neurological clinical picture that can be traced back to damage to the nerves – for example, due to inflammation of the ears. It can also be triggered by an abscess, tumor, or injury. However, often no clear cause can be determined. Sometimes healing occurs spontaneously after a few months. Whether you wait or have a more detailed examination should be discussed with your veterinarian. Because a more precise diagnosis of Horner’s syndrome can be quite costly. In addition to X-rays, computed tomography (CT) and magnetic resonance tomography (MRT) of the skull and neck area as well as CSF examinations are possible. The vet can best estimate what makes sense from the general condition of the cat.

General Disorders & Haw Syndrome

If a bilateral nictitating membrane prolapses without any further symptoms, experts speak of “Haw syndrome”. This is often caused by gastrointestinal problems, for example from parasites. If the entire eyeball of the velvet paw looks sunken, the nictitating membrane prolapse can be the result of severe emaciation, muscle wasting, or lack of water. Cat flu can also lead to a nictitating membrane prolapse.

Feline dysautonomia

Feline dysautonomia is a rare feline disease that affects the nervous system. If this disease is present, the cat often looks generally ill and weak. In addition to the typical prolapse of the nictitating membrane, symptoms include poor general well-being, dry eyes, digestive problems, and dilated pupils. Feline dysautonomia, also known as “Key Gaskell Syndrome”, leads to death in two-thirds of all cats.

Mental problems

In addition to organic causes, psychological problems can be the cause of a cat’s nictitating membrane prolapse. It is an expression of the fact that the cat is stressed and does not feel well. This could be because of moving, bullying by other cats, or changes in everyday routine. Of course, a combination of different factors is also possible in this case: The stressed cat, for example, eats less and loses weight because it feels uncomfortable.

Therapy of Nictitating Membrane Prolapse

The therapy of the change in the eye depends on the respective cause. If it is a bacterial infection, the vet can prescribe antibiotics. If the eye is inflamed, the veterinarian will prescribe anti-inflammatory eye drops if necessary. It is important to administer these regularly as instructed so that the cat becomes symptom-free quickly. If there is a parasite infestation, the cat should be given a de-wormer.

Basically, the therapy depends on the underlying disease. If this is defeated, the nictitating membrane will also withdraw again.

Prophylaxis: Prevent a Cat’s Nictitating Membrane From Prolapsing

Since the causes of a nictitating membrane prolapse are manifold, there are only a few things you can do about it. Protecting yourself from drafts will help prevent conjunctivitis. Regular fecal samples and, if necessary, a worming treatment can protect against Haw syndrome. To put it simply: Anyone who ensures that their fur nose feels physically comfortable and saves them unnecessary stress is well on the way. This is how you prevent possible diseases that can lead to a nictitating membrane prolapse in the cat.

Judy Taylor

Written by Judy Taylor

Judy Taylor combines her love of science and writing to educate pet owners. Her articles on pet wellness, published on a variety of platforms, reveal a deep passion for animals. With a teaching background and shelter volunteer experience, Judy brings expertise to the fields of writing and compassionate pet care.

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