Do Dogs Have a Third Eyelid?


Just like cats, dogs have a third eyelid – but what is it for and are there any conditions which can affect it? Read our Holidays4Dogs article to find out more about the third eyelid in dogs.

The technical name for the third eyelid is, ‘niticans’ or, the ‘nictitating membrane’. It is located in the corner of each of the dog’s eyes. Its purpose is to protect and lubricate the eye via a major tear gland attached to the base.

The third eyelid can vary in colour depending on the individual dog. It is generally a grey colour, but it can also be almost clear. When the dog is sleeping, the third eyelid closes underneath the top and bottom lids to partially cover the eyeball.

If your dog wakes quickly from sleep, you may notice the third eyelid as it slips back behind the eye.

Under normal circumstances, the dog’s third eyelid cannot be seen. However, it is useful to know what it means when the membrane is visible because in this case, it could indicate something is wrong.

If the third membrane is visible it could simply be the dog is feeling under the weather or off colour. However, it could also be an indication of other more serious conditions. The dog must be examined by a vet, particularly if the membrane or any part of the eye is swollen, red, or weepy.

Other eye conditions

One of the most common conditions relating to the eyelids is, ‘cherry eye’. This is a condition where the third eyelid gland has prolapsed. It is seen as a smooth pink, or red lump, on the edge of the eyelid. It resembles a small fruit – hence the term, cherry eye. The condition can cause the dog some significant discomfort and there can be other complications such as conjunctivitis, as a result.

Cherry eye is generally regarded as a congenital disorder. It is particularly known to affect certain breeds more than others. Bassets, Bulldogs, Spaniels, Newfoundland dogs and Pugs are some of the breeds more commonly affected by cherry eye.

If the condition is treated very early on, it is possible to gently massage the tear gland back into place using warm compresses and eye drops (dog-specific).

However, this doesn’t always mean the condition will clear up for good. The safest way to treat cherry eye is to seek veterinary advice.

For chronic conditions, surgery is usually the only option. The vet will attempt to re-attach the duct back into place.  As a last resort, the duct can be removed. However, this will almost certainly result in the dog needing lifelong treatment to manually lubricate the eye.

A less common, but similar condition to the cherry eye is, ‘scrolled cartilage’. This condition involves one section of the cartilage on the third eyelid growing more rapidly than the rest. This results in a scrolling effect – hence the name.  The condition can be confused with cherry eye as the resulting redness and swelling looks very similar.  Scrolled cartilage will almost certainly need operating on to remove the affected cartilage.  Both conditions can affect one or both eyes.


If you notice that your dog’s third eyelid is visible while he is awake, it is always a sensible precaution to have him checked out by your vet to find out exactly what the problem is. and 4Dogs are participants in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn commission fees by advertising and linking to the following websites. Read our full disclosure agreement here.