Prolapse of the Third Eyelid in cats

Author: Dr. med. vet. Gisa Löwe | Last modified: 17.02.2026
Table of contents

When to visit the vet?

Non-urgent see a veterinarian within 2–3 days

?

ORANGE for eye Pain, redness, corneal changes, neurological signs (Horner's), trauma, or if bilateral + sick (systemic). RED for severe Pain, proptosis, or vision loss.

Unsure about what’s wrong with your pet? Feel free to use our Symptom Checker for more clarity

Definition

Prolapse of the third eyelid in cats, also known as “nictitating membrane prolapse,” is a condition where the third eyelid, a thin membrane in the inner corner of the eye, becomes visible and extends over part of the eye.

Can Occur with the Following Diseases:

Basics and possible causes

The third eyelid, also called the nictitating membrane, is a protective membrane that is normally not visible in cats. It serves to moisten the eye and protect it from foreign bodies and injuries. In a prolapse, this membrane becomes visible and can have various causes.

A common cause for the prolapse of the third eyelid is a disease or injury to the eye itself, such as conjunctivitis or a corneal injury. These conditions lead to irritation and inflammation, which causes the third eyelid to become visible.

Systemic diseases that affect the cat’s overall condition can also trigger a prolapse of the third eyelid. These include dehydration, Fever, or infection. In some cases, a parasitic infection, such as that caused by Toxoplasma gondii, can also play a role.

Another possible cause is the so-called “Horner’s syndrome,” which involves a disturbance of the nerve supply to the eye. This syndrome can be caused by injuries, Tumors, or neurological diseases and often leads to a prolapse of the third eyelid.

Typical accompanying symptoms

  • Watery eye: The affected eye may frequently water excessively, indicating irritation or infection.

  • Redness and Swelling: The area around the eye may appear red and swollen, indicating inflammation.

  • Increased blinking: The cat may blink more often than normal or squint, indicating discomfort.

  • Change in the eyelid: The third eyelid is clearly visible and may partially cover the eye.

  • Behavioral changes: The cat may appear lethargic or withdrawn, indicating general discomfort.

  • Loss of appetite: In some cases, the cat may show less appetite, especially if a systemic infection is present.

When to see a vet?

A veterinary visit is urgently required if the prolapse of the third eyelid persists for more than 24 hours or if it is accompanied by other symptoms such as severe tearing, redness, or Swelling. Since the third eyelid can be a sign of a serious disease, an accurate diagnosis should be made.

An immediate visit to the veterinarian is particularly necessary if the cat shows Pain or cannot open its eye. Even if the cat’s behavior changes significantly, such as increased hiding or Aggressiveness, a veterinarian should be consulted immediately.

Symptom recognition for the pet owner and veterinary diagnostic procedure

It is important for the pet owner to observe exactly when and under what circumstances the third eyelid becomes visible. Also note whether other symptoms such as tearing or Behavioral changes occur, to provide the veterinarian with a complete medical history.

The veterinarian will first perform a thorough examination of the eye to rule out possible injuries or infections. This may involve examining the eye for foreign bodies or performing a fluorescein test to make corneal injuries visible.

Additionally, the veterinarian may order blood tests or imaging procedures to identify systemic diseases or neurological problems. These diagnostic steps help determine the exact cause of the prolapse of the third eyelid and plan appropriate treatment.

What the pet owner can do and professional therapy options

Until the veterinary visit, the pet owner should ensure not to unnecessarily stress the cat and keep it in a calm environment. Avoid touching or rubbing the affected eye, as this could worsen the situation.

If the cat allows it, you can try to gently rinse the eye with a sterile saline solution to remove possible irritants. However, this should only be a temporary measure until the veterinary examination.

Ensure the cat has free access to water to prevent dehydration, especially if systemic diseases are suspected. Keep the environment clean and dust-free to prevent further eye irritation.

Outlook on current research

Current research on prolapse of the third eyelid in cats is intensively investigating how various genetic factors can influence susceptibility to this symptom. Scientists are analyzing the genetic predisposition in different cat breeds to find out if certain breeds are more frequently affected. Earlier studies have shown that breeds like the Burmese may suffer more frequently from this problem, which further fuels research into genetic predisposition. By examining genome data, researchers hope to identify specific genetic markers that correlate with the prolapse of the third eyelid.

Another focus of research is on identifying environmental factors that can lead to a prolapse of the third eyelid. This involves examining aspects such as nutrition, habitat, and general health conditions of cats. Researchers are striving to collect epidemiological data to find out if certain environmental conditions or dietary habits increase the likelihood of a prolapse. These studies could help develop preventive measures that cat owners can take to reduce the risk of a prolapse of the third eyelid.

In clinical research, work is also being done to improve diagnostic techniques. Currently, many efforts are focused on refining imaging procedures and other diagnostic tools to detect prolapse of the third eyelid early and accurately. Advances in imaging technology, such as advanced ultrasound and MRI techniques, offer new possibilities for obtaining more detailed insights into the anatomical changes associated with a prolapse of the third eyelid. These advances could enable veterinarians to diagnose more quickly and accurately, thereby improving treatment outcomes.

In addition, there are advances in the development of treatment protocols aimed at alleviating the symptoms of prolapse of the third eyelid. Researchers are investigating innovative therapies, including pharmacological approaches such as anti-inflammatory drugs or even novel surgical techniques aimed at returning the third eyelid to its normal position. This research could lead to more effective treatment for cats with prolapse of the third eyelid in the long term, improving the quality of life for affected animals.

Frequently asked questions

1. What is prolapse of the third eyelid in cats?
Prolapse of the third eyelid, also known as nictitating membrane prolapse, is a condition in which the cat's third eyelid becomes visible and protrudes over part of the eye. It is a common symptom in cats that can indicate various underlying health problems.
2. How do I recognize prolapse of the third eyelid in my cat?
A visible third eyelid that protrudes over or partially covers the eye is the main characteristic. It can occur in one or both eyes and vary in severity. Pet owners often also notice that the affected cat rubs or blinks its eye more frequently.
3. Is prolapse of the third eyelid painful in cats?
The prolapse itself usually does not cause Pain, but it can be uncomfortable for the cat. However, if it is accompanied by other eye problems or infections, it can cause Pain. It is important to have the cat examined by a veterinarian to determine the cause.
4. Can prolapse of the third eyelid disappear on its own?
In some cases, the prolapse of the third eyelid may resolve on its own, especially if it was caused by temporary irritation or mild infections. However, if the symptom persists or worsens, a veterinarian should be consulted.
5. What should I do if I notice prolapse of the third eyelid in my cat?
Observe the cat closely and look for other symptoms such as redness, discharge, or Behavioral changes. Schedule an appointment with the veterinarian to clarify the cause and receive appropriate treatment.
6. Can prolapse of the third eyelid indicate a serious illness?
Yes, prolapse of the third eyelid can indicate serious health problems such as infections, eye injuries, or systemic diseases. Therefore, it is important not to ignore the symptom and to have a veterinary examination performed.
7. Are there preventive measures against prolapse of the third eyelid?
General health care, including regular veterinary check-ups and a balanced diet, can help reduce the risk of a prolapse. Minimizing stress and avoiding eye injuries are also important.
8. What treatment options are there for prolapse of the third eyelid?
The treatment depends on the underlying cause. It can range from administering eye drops or ointments to surgical interventions if anatomical problems are present. The veterinarian will recommend the appropriate treatment based on the diagnosis.
9. Can prolapse of the third eyelid become chronic?
In some cases, prolapse of the third eyelid can become chronic, especially if the underlying cause is not addressed. Early diagnosis and treatment are crucial to prevent long-term problems.
10. Will my cat fully recover after treatment for prolapse of the third eyelid?
In most cases, cats recover well if the underlying cause is successfully treated. The healing process can vary depending on the severity of the disease and the type of treatment. Regular follow-up examinations are important to monitor the healing process.