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What is Horner's Syndrome?

This occurrence is referred to as “Horner’s Syndrome”. It is a neurological disorder that is common in cats and often shows as abnormal eye and facial muscle positioning. The syndrome is usually unilateral, affecting only one side of the face. Damage to the sympathetic nerve path is classified into three areas. A first order injury is called a central lesion, where damage has occurred somewhere from the brainstem to the spinal cord. The second location differentiation is called a preganglionic lesion, referring to damage anywhere between the spinal cord and the superior cervical ganglion synapse (located near the mandible). A third order, or postganglionic lesion is found between the superior cervical ganglion synapse and the ocular nerves.

The autonomic nervous system of a cat is composed of two parts; the sympathetic and parasympathetic nervous systems. The sympathetic nervous system controls automatic or involuntary responses to fight or flight instincts. This involves pupil dilation, blinking, muscle tone and heart rate. The sympathetic nerve pathway is long, ranging from the brain to the chest. Damage to these nerves anywhere along the pathway can lead to the parasympathetic nervous system taking over the normal functions of the sympathetic nervous system. 

Horner's Syndrome Average Cost

From 372 quotes ranging from $300 - $2,500

Average Cost

$600

Symptoms of Horner's Syndrome in Cats

Most of the visible signs of Horner’s Syndrome involve the cat’s eyes. Other symptoms may be present depending on the underlying cause of the syndrome. Signs to watch for are as follows:

  • Ptosis (drooping eyelid)
  • Anisocoria (unequal pupil size)
  • Conjunctival hyperemia (protruding third eyelid)
  • Narrowing of the eye opening
  • Sunken eye appearance
  • Warmth and redness around eye and ear on affected side
  • Drooling
  • Head tilt
  • Stumbling
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Causes of Horner's Syndrome in Cats

The most common cause of Horner’s Syndrome is trauma from serious injury of the head, neck or spinal cord. Some instances of Horner’s Syndrome are idiopathic, carrying no obvious reason for nerve issues. Possible causes include.

  • Car accident
  • Bite wound
  • Benign or malignant tumors in the chest, neck, brain or spinal cord
  • Retrobulbar (behind the eye) disease
  • Middle ear issues
  • Intervertebral disc disease
  • Blood clots
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Diagnosis of Horner's Syndrome in Cats

To diagnose your cat, the veterinarian will need its full medical history for signs of any underlying problems. A complete physical examination will be made of the cat. If the cat is suffering from traumatic injuries, life-threatening issues will be addressed first. In an attempt to identify any causative health issues, the vet will also complete a neurological evaluation and an otoscopic (ear) examination. Horner’s Syndrome will have to be differentiated from other problems that share symptoms such as ear infections, facial paralysis, and Key-Gaskell Syndrome. 

A phenylephrine test may be performed to locate any sympathetic nerve path damage. The longer the pupil takes to return to normal size after drop administration, the further from the eye that the damage is. Full blood work will be taken including a complete blood count and a biochemical profile to help identify any health issues in the body. Urinalysis may also be used for this purpose. If spinal cord or brain damage is suspected, cerebrospinal fluid samples may be collected for testing.

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Treatment of Horner's Syndrome in Cats

Horner’s Syndrome is a group of symptoms and not a disease itself. If no underlying cause can be identified, the issue may resolve on its own. Treatment of symptoms can provide relief as the cat experiences them. If a primary health issue has been found, proper treatment can reverse the syndrome. 

Eye Drops

 

If the cat’s eyes are irritated from the many effects of Horner’s Syndrome, eye drops may be prescribed to help ease blinking and to soothe and minimize any ocular ulcers. If the cat is suffering from an inappropriately dilated pupil, phenylephrine drops may be used to correct the issue.

Surgical Removal

If a tumor has been identified as causing the nerve damage, removing it may relieve symptoms. This may or may not be possible depending on the location of the tumor. Surgery should only be performed if the risk is less severe than the symptoms that exist, or if the tumors are cancerous. General anesthesia is used for the procedure.

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Recovery of Horner's Syndrome in Cats

If your cat has undergone surgery, be sure to follow all at-home instructions for care. Monitor the incision site daily to check for swelling or bleeding. If tumors have been found as the cause of Horner’s Syndrome in your cat, prognosis may be guarded. If the syndrome was a result of trauma and the cat survives all other injuries, the chance of recovery is quite good. 

In cases which the syndrome develops suddenly and no cause is identified, the nerve issues may resolve on their own. Sometimes this can take up to 16 weeks to occur. In some instances, Horner’s Syndrome may be permanent due to irreversible damage, however, this is rare. 

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Horner's Syndrome Average Cost

From 372 quotes ranging from $300 - $2,500

Average Cost

$600

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Horner's Syndrome Questions and Advice from Veterinary Professionals

Need pet health advice? Ask a vet

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Lilly

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Domestic shorthair

dog-age-icon

3 Years

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Moderate severity

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2 found helpful

pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Moderate severity

Has Symptoms

Loss Of Appetite
Stumbling
Third Eyelid Showing
Unequal Pupil Size

Our cat Lilly went to the vet for her annual checkup. Our vet administered Claro to both ears for an ear infection. Within an hour Lilly began to stumble and have issues with balance. I assumed the medicine was just messing with her equilibrium, but then I noticed her third eyelid began covering half her eye. We took her to the vet and they observed her, dried her ears out and gave her medicine for motion sickness and her condition improved greatly. Her third eye was still protruding but not near as much. However within a day she was back to the same condition as before and has not improved since. Is there nothing more we can do but wait and for ear infections or for medications that cause Horner’s is there a time frame of recovery?

Sept. 22, 2018

Lilly's Owner

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Alvin

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Ragamuffin

dog-age-icon

14 Months

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Moderate severity

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pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Moderate severity

Has Symptoms

Third Eye Lid Over Half His Eye

My cat has just had surgery for ventral bulla osteotomy in his left ear, he had polyps in his middle ear, he has been left with horners syndrome. Will this be permanent? How long will it last, his third eye lid is over the middle of his eye

July 14, 2018

Alvin's Owner

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Dr. Michele K. DVM

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0 Recommendations

Nerve damage is common with that procedure, and it can be temporary or long lasting. Sometimes one just has to wait and see how he is going to recover, and that may be the case for Alvin. In the meantime, he may need drops for his affected eye if he is not blinking as much - it would be a good idea to call the surgeon who performed the procedure, get their opinion on the situation since they were there, and see if they would recommend medications in the meantime.

July 14, 2018

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Smokey

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Shorthaired

dog-age-icon

14 Years

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Moderate severity

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1 found helpful

pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Moderate severity

Has Symptoms

Dilated Pupil Inner Eyelid Showing

My cat has Horners Syndrome in his right eye. Vet says it may be idiopathic. However, I just found out my husband has sometimes been giving my cat his insulin injections on that side of his neck rather than in the scruff of his neck. Could this have possibly caused the Horners Syndrome?

July 12, 2018

Smokey's Owner

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Dr. Michele K. DVM

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1 Recommendations

I think it would be unlikely that the insulin injections under his skin on that side of his neck would cause the Horner's syndrome. Most cases are idiopathic and resolve with time, as long as ear problems and other neurologic disease has been ruled out.

July 12, 2018

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Sam

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mixed

dog-age-icon

9 Years

pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Fair severity

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2 found helpful

pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Fair severity

Has Symptoms

Head Shake
Uneven Pupils
Third Eyelid Cover Eye
Chronic Ear Infection

My Cat has Horner's Syndrome. We tried 2 weeks of antibiotics. About 1.5 weeks into the antibiotics the third pupil started to retract and she looked like she was on the mend. About a week after the antibiotics, the third eyelid started to get stuck open again, and the uneven pupils worsened. She has no other symptoms other than the Horner's Syndrome and the ear on the same side of the eye issues is the chronic ear infection ear. The original diagnoses was a middle ear infection. I took her back to the vet today. The vet (who is new to me because of moving across country) also wants to run a really expensive CT scan. I cannot afford a CT scan on myself (with insurance) let alone on a cat without insurance. They keep telling me she's old and there could be other problems. But there are no other symptoms. She would have other symptoms I would think if it was something serious. Given that the eye issues got better with the first round of antibiotics, I would think that is sign enough that it can be treated with antibiotics, she just needed them a bit longer. I know there are suppose to be other symptoms with middle ear infections, and she does not have them. Is there anything else it could be (besides a middle ear infection)? Would anything else that causes Horner's Syndrome also get better on antibiotics?

June 9, 2018

Sam's Owner

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Dr. Michele K. DVM

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2 Recommendations

It seems very related to me that the Horner's is on the same side as her chronic ear infection ear, as ear infections are one cause for Horner's syndrome. It would make sense to me to treat that infection until it has resolved, and monitor her for any signs of deterioration. If she is doing well otherwise, I'm not sure that you need to aggressively pursue a diagnosis, but since I cannot examine her, that would be a decision to make with your veterinarian.

June 9, 2018

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Izze

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tabby

dog-age-icon

10 Years

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Moderate severity

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2 found helpful

pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Moderate severity

Has Symptoms

Ear Itching
Head Tilt
Conjunctival Hyperemia
Normal Temperature
Different Dilation Of Pupil

My cat just got back form the vet earlier today. She has her second eyelid over 1/3 of her eye, and her pupil in that eye is differently dilated than the other. The vet was very short and new since we just moved. He told me to give her Clindaymycin over the weekend and if she is not better by Monday/Tuesday bring her back for blood test. He said the underlying causes was likely neurological, but he did not expand upon what that meant. I am thinking the worse (she's going to die level of worse). She is perfectly fine other than that eye issue. Her ear is fine (he checked it), she eats well still, drinks, uses the litter box, and plays. She did not have a fever and her temp was normal. She was so ok, they went ahead and gave her a rabies vaccine today (she was due in a couple of weeks anyways). What else could be causing her eye issue? No trauma. what are the possible neurlogical disorders and what is the probability that the clindamycin will work. I am worried sick about her and I am not sure if I should seek another opinion becuase she seems fine besides her eye.

May 19, 2018

Izze's Owner


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2 Recommendations

It certainly does sound like Horner’s Syndrome with the unequal pupil size, third eyelid showing on affected side, head tilt etc… Many times these cases may be idiopathic; but other causes like middle ear infection, trauma, poisoning among other causes may also lead to these symptoms. If Izze doesn’t improve over the weekend (since she seems otherwise in good spirits) you may return to the Veterinarian or visit another one to get another opinion. Regards Dr Callum Turner DVM

May 19, 2018

Thank you. The night of your reply went to the emergency vety because Izze started to act like she had trouble walking with her left front paw (she kept it up when walking and would lay down every couple of steps). Izze walked fine as soon as we got the emergency vet. But the emergency vet went ahead and examined her and diagnosed a middle ear infection and put her on an additional antibiotics. She told me it could take up to 3-6 weeks for the Horner's syndrome to clear up. I am not sure if I should just wait to see if it happens? It seems like a long time to just let it ride out, and hope for the best. I know the middle ear infection can get worse, especially since the ear drum thing was intact (which it is for Izze). If she were in any pain or showing any other symptoms this would be easier. But she is fine as long as you do not touch her left ear. If you touch the left ear she shakes her head or sometimes tilts it. It has the black discharge in it, she has had since I adopted her over 10 years ago.

May 24, 2018

Izze's Owner

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Mercury (Beanie)

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Tuxedo

dog-age-icon

3 Years

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Moderate severity

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pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Moderate severity

Has Symptoms

Loss Of Balance
Pupil Smaller Than The Other
Third Eyelid Showing
One Dilated Pupil
Defecating Outside The Litter Box

about a year ago a cat my cat showed up outside my house as a stray, skinny, with ear mites and goopy eyes. I took him in and got him help, he’s been neutered, shots etc. He has had an ear infection practically since being with me, he was treated for it on the same day as being treated for mites. The mites went away but the ear infection has not, he's been treated probably once a month. Only one ear has issues, the right side, the left is fine. I noticed again he was scratching at his right ear so decided to take him in to see the vet. I trust my vet, my family takes all of our animals there.. my vet said his ear looked fine, or at least as if it was getting better and that with another round of Claro and a Depo Medrol shot he should be good to go. Mercury likes to hide under the blankets in his kennel when we go to the vet, and so when I met the vet at the door (due to COVID precautions) to pick him up, he was hiding and I couldn’t see him. 10 minutes into the car ride he comes out from under the blanket and I turn around and look at him and one of his pupils was huge, and the other very small. He was not showing any signs before visiting the vet this time, I have never seen his eyes do this so I am very scared. I decided to take him home anyways and assumed he was just super stressed out and needed to relax, I brought him home and noticed he acted confused and had a hard time keeping his balance. He defecated outside of his litter box, his inner lid was showing, and had one pupil bigger than the other still. I called his vet immediately and they said to bring him back in and they would keep him overnight, after leaving him I got a call saying he was being put on fluids and given an antibiotic bc they’re worried about infection and that it was worrisome his eyes looked like that still. I am just reaching out for help bc I’m very worried and willing to take any advice or experience into consideration. I will know more tomorrow morning from my personal vet but while I wait I can’t help but look. Thank you!

dog-name-icon

Andy

dog-breed-icon

Korat

dog-age-icon

11 Years

pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Moderate severity

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0 found helpful

pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Moderate severity

Has Symptoms

Eye Redness
Eye Discharge
Sunken Eye
Exposed Sheath
Closed Eye Lid

My 11 t/o male cat, who goes outside and eats the animals he hunts, has developed Horner's Syndrome. He's been to the vet where they checked his ears and didn't see any infections, and he hasn't had any physical trauma that we can tell. I'm hoping this goes away on its own, but wondering if it's ok to still let him go outside in the meantime.

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Mimi

dog-breed-icon

Manx Cat

dog-age-icon

11 Years

pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Fair severity

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0 found helpful

pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Fair severity

Has Symptoms

Eyelid Squinting
Inner Eyelid Showing

My cat had a bacterial ear infection, the vet gave her two shots one for inflammation and the other an antibiotic when he have the second shot she had a spasm like he hit a nerve. He then gave me off lable Mometavet ear drops for 10 days which I did but her ear still has a discharge and now her third eyelid is stuck.(on the right same as the bad ear infection). Could this be Horner's should I wait it out or take her back?

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Clark

dog-breed-icon

Flamepoint

dog-age-icon

6 Months

pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Moderate severity

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0 found helpful

pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Moderate severity

Has Symptoms

Vomit

I rescued an 8 week old kitten that I saw get thrown from a vehicle on the highway dec 17th. I was able to catch him and we went straight to the Vet. Other than a few scrapes on his chin, paw pads and butt he checked out ok. Bloodwork was all good but I noticed that one eye looked smaller than the other and the 3rd eyelids were protruding. He was also vomiting after waking up sometimes. We have seen our vet Three times along with an ER vet since and she said everything checks out good on exam and blood and urine but that she did notice his third eyelids. We finally found a wet food that he can tolerate and the vomiting has decreased drastically but dry makes him vomit. The third eyelids are still an issue and I feel like when he wakes up and can’t see great because of the eyelids, he gets nauseous and vomits? Should I seek an optimologist for animals?

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Missy

dog-breed-icon

mixed

dog-age-icon

10 Years

pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Serious severity

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0 found helpful

pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Serious severity

Has Symptoms

Can’T Hear 3Rd Eyelid Won’T Close

Took my cat in for checkup , vet said she had dirty ears and a temperature. I picked her up and driving home I notice she made no noise got home got her out of carrier and notice her 3rd eyelid was half way up her eye and she was acting funny. Called the vet and he had left for the day. An hour later I took her to the emergency vet . The vet there said it looks like harnors syndrome she looked into her ears and there was so much medicine in there she could even see the eardrum and couldn’t tell if her eardrums were ruptured. She now can’t hear and barely can see and won’t eat . I’m so stressed and don’t know what to do

Horner's Syndrome Average Cost

From 372 quotes ranging from $300 - $2,500

Average Cost

$600

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