As I dog owner myself, I can empathize with how unsettling it can be to see your fluffy friends’ eyes rolled back.
While this could denote many things, it is possible that it is a harmless occurrence, and so it is important that you relax and take the necessary support from your vet in addressing this condition.
Although I am not a licensed veterinarian, I have thoroughly researched this subject, and have put together a small brief to have you well informed on this subject.
Understanding the Nictating membrane AKA The third eyelid
It’s a common mistake for many to see the dog’s ‘third eyelid’ and confuse it with their dog’s eyes rolling back. This eyelid, medically known as the nictating membrane, or ‘haw’, is usually invisible and functions when the dog closes their eyes. It’s possible that the third eyelid can have varying colors, depending on the dog breed.
There are many functions to the third eyelid:
- The third eyelid is a protective shield that guards the cornea against injuries
- Acting like a windshield wiper, it wipes of any mucus, debris, or dirt that accumulates the cornea over time
- It plays an important role in their tear gland, as it produces 1/3rd of the dog’s tears
- Its lymphoid system generates immunoglobulin that helps fight infection in the eye
You can clearly see the third eyelid– usually present in the corner of the eye – when your dog jolts up from a nap or if you manually expose it yourself. You can do this by lifting the dog’s eyelid when they are sleeping. The nictating membrane covering the cornea is what many believe that the dog’s eyes roll back when sleeping.
If the third eyelid is visible even after the dog is fully awake and active, it can be a cause signal that your dog is in potential danger and requires immediate medical attention. There is a long list of possible conditions that could cause the third eyelid to be visible. I have listed the more prominent ones below…
The Nystagmus conditions stem from a complication in the sensory system, responsible for the balance of the dog’s head and body. It shows itself mostly through involuntary eye movements, and is classified into two types:
- Pendular Nystagmus – eyes oscillating back and forth in small movements at the same speed
- Jerk Nystagmus – eyes move slowly in one direction before suddenly jerking the other way
Nystagmus can also show symptoms of head tilting and circling. The prognosis and recovery time would depend on the main causes behind the condition. It is possible that the dog may have nystagmus from birth and can blow out into a condition once it’s grown up.
Some of the main causes of Nystagmus are:
- Physical trauma or accident
- Tumors or Cist (around the eye or nervous system region)
- Exposure to toxins such as lead
It is possible that a neurological disorder can cause the nerves, responsible for holding the third eyelid in the socket, to be less functional. So, the third eyelid, instead of staying in the corner, may protrude onto the eye creating an obstacle for the dog to see.
The most common disorder of such is Horner’s syndrome. Although Horner’s syndrome is never categorically determined, it is usually linked with head trauma and growth pressing on the dog’s nerves. There are a few symptoms you can watch out for –
- Droopy facial features
- Sunken eyes
- Droopy eyelids
- Small pupil size
This disorder is largely found in golden retrievers and cocker spaniels, although it can develop in other breeds as well.
As the name suggests, the Cherry eye condition occurs due to the third eye turning into a fleshy red mass, on one or both sides of the eye. The fall of the third eyelid leaves its gland vulnerable and exposed.
It’s essential that we treat this condition quickly, by having a close inspection of the nictitating membrane as it can produce an abnormal volume of tears and therefore leading to dry eye syndrome. It can be treated through manual massage manipulation at its earliest, or a gland surgery replacement at its advanced stages.
There are many medications, especially painkillers or tranquilizers, that have strong side effects to cause a dog’s third eyelid to show up. Usually, these side effects wear off in quick time – however please ensure to have a conversation with your vet to pinpoint the most appropriate medication for your dog.
The medication is usually prescribed considering the following factors of your dog – their medical history, age, weight, health condition, and diagnostic purpose. It is crucial that you follow the medicine instruction, either by the vet or from the medicine box, to avoid any fatal reaction from a wrong medical dose.
Any severe pain, from anywhere in the body can cause a dog to roll their eyes back. The third eyelid may also be a source of this pain as it is often levy to small scratches or wounds. It could also be pain from an injury sustained or pain from their internal organs.
Some symptoms to keep an eye out for:
- Loss of appetite
- Feeling lethargic
- Excessive drooling
- Weight loss in a short period of time
- Restlessness at rest hours (night)
They may not necessarily express their pain reaction in the range listed above. As different dogs may react to pain differently, it is up to you to recognize if your dog is behaving in an unusual manner.
Seizures are a result of abnormal activity in the brain. They happen when the brain misinterprets an electric impulse and triggers muscle movements controlled by that area of the brain that is abnormally functioning.
Dogs can experience seizures in many ways, they can become:
- Unnaturally stiff
- Shake uncontrollably
- Collapse suddenly
- Lose consciousness
They can also have what is known as ‘silent seizures’ which affect a limited part of their body, like their eyes. Although it may be quite jarring to witness for the pet owner, a seizer usually isn’t painful for the dog. It can, however, create panic and confusion for them after an episode.
A seizure can be caused by pre-existing medical conditions like epilepsy, traumas, infections, exposure to toxic elements, or other infected animals. There is only one way to eliminate these episodes, and that is to solve the core issue behind the seizure. It can be fully treated or may require the dog to go through medical treatments for its entire life.
The foremost thing we can do is to be vigilant for any signs of the third eyelid appearing. If it does, you can make a quick evaluation to see the possible causes and take him to the vet immediately. If the third eyelid seems to appear for a very short period of time, then you need to bother, but still, be observant to see if anything unfolds.
Hope you found this article informative in understanding why third eyelids may appear. Please feel free to share your thoughts and comments below!