If your dog seems to have a weird, droopy eye, along with a few other symptoms, then it could be the case that they have developed a condition known as Horner’s syndrome. Characterized by a series of symptoms, the condition isn’t usually painful and does not affect what your pet can or can’t see, but it could be a sign of something a little more serious going on.

Let’s dive deeper into Horner’s syndrome in dogs, so you know exactly what to be on the lookout for.

Stop Googling - Ask a Real Vet


  1. What is Horner’s Syndrome in Dogs
  2. Symptoms of Horner’s Syndrome in Dogs
  3. What Causes Horner’s Syndrome in Dogs
  4. Treatment for Horner’s Syndrome in Dogs
  5. FAQs
  6. Conclusion

What is Horner’s Syndrome in Dogs

Horner’s syndrome is a neurological medical condition that is relatively common and usually not immediately serious, but certainly can be. Affecting the face and eyes, and usually only one at a time, it can have several causes. Oftentimes, though, it is idiopathic, which means that there is no obvious or direct cause.

The syndrome is not thought to cause pain for your dog, but it does show some damage to your dog’s nervous system (sympathetic) specifically the innervating nerves that control the facial muscles and eye muscles.

Symptoms of Horner’s Syndrome in Dogs

Symptoms of Horner’s syndrome in dogs can appear at any time with zero notice, which is why you must monitor your pet at all times. I have Petcube’s Bites 2 Lite, which allows me to monitor Frank and The Cat when I’m not in the house (or room), as well as tell them “no” when they’re acting naughty and fling treats when they listen to me (rarely). It has two-way audio, too, so I can listen out for any whining or unusual vocal noises.

Anyway, let’s get back to the symptoms.

Look out for the following, which are usually the first signs of Horner’s syndrome in dogs:

  • Constricted pupil (miosis);
  • Eyelid drooping (ptosis);
  • Redness;
  • Swelling;
  • Issues with the third eyelid;
  • Obvious signs of irritation (scratching, pawing, etc.);
  • Appearance of sunken or retracted eye (enophthalmos);
  • Behavioral changes include whining, snappiness, and agitation.

More often than not, these symptoms will appear on one eye or eyelid only, called unilateral. It can happen on both eyelids at the same time, though, and is known as bilateral Horner’s syndrome.

In rare cases or cases with complications, other symptoms can arise. These include skin color changes on the ear and nose, moving around in a jagged or staggered way, problems with chewing food, issues with vision, and even limb paralysis, but this does depend on where the nerve damage has occurred.

What Causes Horner’s Syndrome in Dogs

As mentioned previously, the causes of Horner’s syndrome in dogs are plentiful, but it always points towards damage to the sympathetic nervous system, which controls your “fight or flight” reflexes, specifically the spinal cord between the brain, eyes, neck, and chest. The common cause of this damage is an infection in the middle or inner ear, but there are plenty of others. These include:

  • Trauma or injuries, such as vehicle collisions or animal attacks;
  • Bacterial or fungal infections;
  • Complications from infections, such as abscesses or disease;
  • Vestibular disease;
  • Blood clots;
  • Cancer;
  • Benign tumors;
  • Diabetes;
  • Ocular disease;
  • Neurological conditions;
  • IVDD (Intervertebral Disc Disease);
  • Spinal strokes;
  • Regular and strong lead pulling;
  • Inherited (very rare).

According to NCBI studies, a few dog breeds develop Horner’s syndrome at a slightly higher rate than others: Border Collies, Shetland Sheepdogs, Labrador Retrievers, Weimarnarers, Dobermans, and Golden Retrievers. The syndrome is also more common in dogs that are at least five years of age, up to eight years of age.

If you have a dog breed that is predisposed to conditions just like this, it’s well worth researching those conditions and putting extra precautions in place. There’s a whole world of pet tech out there these days, with GPS trackers, 360-degree pet monitoring cameras, automatic feeders, and more. They can all help you keep tabs on the health and well-being of all household pets with the simple tip-tap of a finger.

Treatment for Horner’s Syndrome in Dogs

Some dogs won’t need treatment, and the dropping eyes and other symptoms of Horner’s syndrome will go away on their own. This isn’t the case for all dogs, though. The condition could appear mild and non-problematic at first, which makes it seem less urgent in terms of vet appointments and treatment. With neurological problems, the situation can change quite literally in the blink of an eye, so I don’t recommend waiting and seeing.

The underlying causes, if there are any, need to be investigated and then diagnosed alongside treatment for Horner's syndrome itself. An infection may need antibiotics and/or antifungal treatments, and eye drops can alleviate any redness or discomfort.

If there are no underlying causes, you can expect full recovery in one to two weeks (fast) or a few weeks or months (slow).

Are you aware that Petcube has a range of vets, available 24/7 and unlocked with an Emergency Fund subscription? It doesn’t matter whether it’s 4 p.m. or 4 a.m.; they’re on hand, ready to answer your questions and, if necessary, direct you toward urgent medical intervention. That actually brings me nicely to my next point.

The Emergency Fund doesn’t just give you any time access to fully trained, qualified, and licensed vets; it also gives you access to up to $3,000 of emergency vet care for up to six of your pampered pets, all for less than $1 per day.

But wait, it gets better! I’d like to offer you an exclusive discount of 27% off the regular subscription price, just to say thanks for stopping by and reading the blog today. You can find out more by using this link.


Can dogs live with Horner’s syndrome?

Yes, dogs can live quite happily with Horner’s syndrome, provided there are no underlying causes. Once the symptoms go away, there are usually no long-term issues. If there are underlying causes, such as neurological conditions or issues, the prognosis and outlook will depend on those.

How do you fix Horner’s syndrome in dogs?

Unless your pup has underlying medical conditions, such as neurological disease, treatment will be for those. Horner’s syndrome and the symptoms it brings usually disappear by themselves if there are no underlying problems, but it can take a while for everything to completely clear up. I do not recommend treating this yourself without veterinary assistance, just in case.


It’s never nice to see your pups sick or injured, but these things will happen from time to time. Horner’s syndrome is quite common, isn’t painful, and doesn’t really do much in the way of damage. Some of the underlying conditions that can cause it won’t. For that reason, you should always seek assistance from a professional when you notice anything out of the ordinary with your pets. Your early response could mean the difference between life and death in many more cases than you’d think.

Was this article helpful?

Help us make our articles even better

Yes No

Thank you for your feedback