Why Do My Dog's Eyes Look Sunken In?

dog sunken eyes, dog eyes sink in, dog horner's syndrome
dog sunken eyes, dog eyes sink in, dog horner's syndrome

Table of Contents

1) Pay Attention to Sunken Eyes in Dogs

2) Causes of Unilateral Sunken Eyes in Dogs

3) Causes of Bilateral Sunken Eyes in Dogs

4) The Bottom Line

5) Further Reading

6) Comments

Pay Attention To Sunken Eyes in Dogs

If you wake up one morning and find your dog's eyes sunken in, you may be wondering what is happening and you'll obviously be concerned. The reasons why a dog's eyes would sink in are several, ranging from not-that-severe issues to more severe ones requiring immediate veterinary attention. First and foremost, what's a sinking eye and how does it look like? The medical term for sunken eyes is enophthalmia, meaning "recession of the eyeball within the orbit."

A dog's eyes sit in the eye socket, a bony cavity in the skull with a concave shape meant to purposely accommodate the eyes. Normally, eyes in dogs are neither sunken (enophthalumus) nor bulging (exophthalmos); rather, they're sitting well into the eye socket, but in certain breeds though, prominent, loosely-set eyes are the norm as seen in the pug, Pekingese, Boston terrier, French bulldog or shih tzu, while, on the other hand, the eyes in some breeds are set deep as seen in long-nosed breeds such as the collie. When eyes appear abnormally sunken, they will be likely noticeable to owners, but how does this exactly happen? What mechanism is behind sunken, hollow eyes in dogs? There are different dynamics that could take place when we see a sunken eye in dogs. Following are a few:

  • Fat pads, which sit under the dog's eyes, are responsible for providing padding in a cushion-like manner and allowing free movement of the eyes. When these fat pads atrophy though, usually due to loss of fat, the eyes appear sunken in.
  • According to the Merck Veterinary Manual,the dog's eyes have a retractor muscle that when it spasms, it causes the eye to sink in. This can happen in certain local or systemic medical conditions we will see below.
  • Sunken eyes may also be seen when a group of nerves of the sympathetic trunk are damaged. These nerves branch off from the spinal cord in the dog's chest, and then climb upwards to the neck and face. The sunken eye is found on the same side of the damaged nerves.
  • Another reason could be the presence of a mass. While masses arising from the posterior part of the eye cause the eye to protrude, masses found in the front, anterior part of the eye, cause the affected eye to sink in, explain William C. Aaroe, a veterinarian and Juliet R. Gionfriddo, a veterinary ophthalmologist in an article for DVM360.

The causes of sunken eyes in dogs are various, and when it comes to diagnostics, a lot can be deduced based on whether the sinking affects one eye or both. In the next paragraph, we'll see some causes of sinking eyes in dogs.

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Veterinarian Karen Becker Talks About Horner's Syndrome

Causes of Unilateral Sunken Eyes in Dogs

If your dog's eyes appear sunken, of course you should see the vet to determine what's exactly going on. The following conditions listed below are NOT a diagnosis and not meant to substitute professional veterinary advice. They may help you though understand common causes and help you realize why that vet appointment shouldn't be delayed. Following are some causes of sunken eyes in dogs. They have been divided in sections so to differentiate problems commonly affecting only one eye or both.

Causes of Unilateral Sunken in Dogs

When a dog presents with only one sunken eye, it's often a sign of a problem within the eye itself, but not always. Several causes of sunken eyes in dogs fall under the Horner's Syndrome category. According to Eye Care for Animals: " A syndrome is a collection of symptoms that often has a limited number of causes and can thus help doctors diagnose the underlying problem." Horner's syndrome takes place when the group of nerves leading to the eyes are damaged. In this syndrome, the dog develops sunken eyes along with an elevated third eyelid, a droopy eyelid and often one pupil smaller than the other one. The causes are various. Following are some conditions commonly affecting one eye.

Traumatic Eye Injury

Veterinarian Dr. Christian K. explains that sometimes an eye injury can cause a loss of fluid from the inside that causes the eye to sink in. The eye is usually painful. Also, painful eye conditions such as uveitis, conjunctivitis and presence of eye ulcers may trigger the dog's retractor bulbi muscles to retract the eye globe back into its socket as a protective measure. When dealing with eye injuries, it's important to see the vet the same day as they may considerably worsen quickly and vision loss is possible.


As mentioned, masses in the anterior portion of the eye cause the eye to sink in. These masses can be accompanied by an elevated third eyelid. The masses are typically minimally painful and slow to progress. Ocular masses may sometimes be benign, but they also can be malignant and spread to other body parts (metastasizing).

Horner's Syndrome

This is a neurological cause of sunken eyes in dogs, even though sometimes, an exact cause cannot be found, which in this scenario, Horner's syndrome is referred to as being "idiopathic". When the cause is neurological, how are the dog's eyes affected? An injury to the neck or intervertebral disc disease may damage the nerves of the spinal column leading to the eyes and trigger Horner's syndrome. Other potential causes of Horner's may be a middle ear or inner ear infection, head injury, a growth pressing on nerves,a bite wound, use of choke collars or even a recent blood sample taken from the dog's jugular vein.. Symptoms include:

  • Enophthalmos (sunken eye)
  • Ptosis (droopy eyelid)
  • Miosis: (constricted pupil)
  • Presence of nictitating membrane (protruding third eyelid)

In this syndrome, the affected eye is not painful, but dogs may have trouble seeing. The effects on the eyes as mentioned are caused by some sort of damage to the nerves responsible for important functions such as the size of the pupils.The damage can occur anywhere along the nerve's pathway including within the brain and spinal cord, between the chest cavity and the base of the skull, and between the base of the skull and eye. The vet will therefore need to determine the exact problem area. When a cause cannot be found, it's known as "idiopathic."

Example of Horner's Syndrome in Cat

Cat with Horner's syndrome
Cat with Horner's syndrome | Source

"Dogs do not have the range of eye movements that humans do, but they can move their eyes in one direction people can not: backwards! They have a muscle that humans do not, the retractor bulbi, which enables them to retract their eyes back into their sockets---an ability you may be reminded of when you try to put drops in your dog’s eyes."

— D. Caroline Coile Ph.D

Causes of Bilateral Sunken in Dogs

In some cases, both eyes appear sunken. When this happens, the cause is often more systemic than localized. This means it affects multiple body parts and very likely there are other accompanying symptoms affecting other body parts or organs. Following are some causes of eyes sinking in affecting both eyes.


Since the body is for the great part made of water, dehydration causes shrinkage of all the major tissues, including those fat pad found around the eye. Also, the water content within the eyeball is affected.Therefore, when a dog is severely dehydrated, the fat pads behind the eye lose substance and eyeball dehydrates causing the eyeball to sink in. Usually dogs with this level of dehydration will also have dry gums, dry nose, dry eyes and loose skin that stays lifted over the shoulder blades and back when lifted up.

Weight Loss

Dogs that are emaciated and suffer great weight loss also have sunken eyes since again those fat pads will be depleted and atrophied. Malnutrition, starvation and weight loss may therefore be another cause for sunken eyes in dogs.

Systemic Diseases

Systemic diseases affect several body parts and therefore there are several symptoms and these may include the eyes which may appear sunken. Tick paralysis, may cause many neurological complications including abnormal reflexes, weakness and sunken eyes. According to the Dog Owner's Veterinary Handbook, tetanus may cause the retractor muscles of the eyes to spasm in both eyeballs, causing the sunken eye appearance accompanied by exposure of the dog's third eyelid. Other systemic conditions such as parvo, may cause sunken eyes secondary to dehydration.

The Bottom Line

As seen, there are several reasons dogs may develop sunken eyes, and as seen, they're all quite serious. If your dog presents sunken eyes or any other abnormalities, please see your vet.

Disclaimer: this article is not to be used as a substitute for professional veterinary advice. If your dog has sunken eyes of any other eye abnormality please see your vet for proper diagnosis and treatment.

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Share thoughts on sunken eyes in dogs with the world 4 comments

peachpurple profile image

peachpurple 17 months ago from Home Sweet Home

Oh that a symptom. I though he had sleepless night

Kathleen Kerswig 17 months ago

Anyone who is a dog-lover could benefit from this article. This information could help someone who would not normally have paid attention to their dog's sunken eyes. This is a good thing you are doing - helping pet owners take better care of their beloved pets. Blessings!

alexadry profile image

alexadry 17 months ago from USA Author

Thank you Kathleen, indeed, some physical changes are not that evident, but if we pay close attention and learn what to look for, we can better understand what the dog's body is trying to say so we can take care of them and have them see the vet.

torrilynn profile image

torrilynn 17 months ago

thanks for the useful article. its always best to notice the symptoms and signs ahead of time. best of wishes.

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