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.
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
- Head tilt
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
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.
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.
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.
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.
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.
Horner’s Syndrome Questions and Advice from Veterinary Professionals
Hello, I had my five-year-old cat treated for minor ear buildup. He was administered claro. My veterinarian has been in business for 30 years and I do trust him. However, after leaving his office my cat immediately showed signs of Horner's syndrome. It has now been over 36 hours and he is not showing any signs of recovery. His symptoms include falling down to the side, not using his litter box properly, lifting of the third eyelid, pupil not dilating properly and overall just not himself. I have taken him back to the same vet two times since the medication was given, he was then administered an anti-inflammatory, and antibiotic, a dietary supplement and fluid for hydration. My veterinarian did not tell me it was Horner's syndrome until after we told him that we knew it was. He then admitted that his eardrum was most likely ruptured while administering the claro which caused the trauma to lead to Horner's syndrome. I would like to know if you agree with this advice, if you have any advice on what I should do next other than "wait it out" and do you think with this type of injury he will recover from Horner's syndrome? Thank you so much and any information is extremely helpful as I am greatly concerned.
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Hornets srndrom and inner ear infection
My cat recently developed this unfortunate issue for which he has been to the vet. He's been examined and had his ears flushed as it looked like the ear on the same side had experienced quite a bit of trauma and irritation. No mites etc. We're the cause, he is a Cornish rex and they can be prone to ear problems. Although his ears do not seem to be bothering him now, his eye has not returned to normal. I'm wondering if I should follow up by giving him drops? Also if I should be concerned there is another underlying issue?
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Hi. My cat has undergone castration surgery and since returning home has symptoms of horner syndrome. Does this usually occur? I am worried. The vet said it could be from stress and that it will pass. It's been five days since the surgery and the cat's eye continues with the symptoms. Should I look for another vet? Many thanks for any help.
Post surgical ptosis is rare but may occur; it may resolve itself after a few weeks (around four to six). Other causes include trauma, inflammation, neurological conditions, poisoning or idiopathic; an examination of the ears and a neurological examination will rule out other causes. Eye drops will be required if Trufa cannot blink so that the conjunctiva will remain moist. Regards Dr Callum Turner DVM
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Hi. My cat has never had any operation, its active around the house and outdoor as well. 3 days ago, the eyes were looking strange and looks like the eyelid is dropping, its not feeding well but looks healthy apart from the eyes. What can be the problem? I hope that it will be ok, i have had the cat for 4 years.
Horner’s Syndrome (and similar conditions) can be caused by local inflammation, trauma, poisoning, tumours etc… which would explain the drooping eyelid and eating difficulties. Many times, these occurrences resolve themselves; however I would still recommend visiting your Veterinarian to be on the safe side. Regards Dr Callum Turner DVM
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