Horner’s Syndrome in Cats

A syndrome is an identifiable collection of symptoms and physical features that indicate a specific ailment for which the reason is unknown. As a result, doctors refer to the famed “viral syndrome” as such in practice due to the lack of knowledge about which viral agents are causing the sickness. Physicians may refer to a causative agent or process as a disease, not a syndrome if medical research has identified it with a high degree of certainty. By virtue of its recognizable diagnostic symptoms, disease progression, and responsiveness to a specific treatment, Mucocutaneous lymph node syndrome became Kawasaki syndrome, which then metamorphosed into Kawasaki disease; the latter is appropriately a disease, not a syndrome.

Horner’s Syndrome in Cats: What is it?

It’s a neurological condition that affects many cats and manifests itself in the aberrant eye and facial muscle alignment. The Syndrome usually affects only one side of the face and is unilateral. There are three types of damage to the sympathetic nerve route. A central lesion is a first-order injury that occurs anywhere between the brainstem and the spinal cord. Damage somewhere between the spinal cord and the superior cervical ganglion synapse is referred to as a preganglionic lesion in the second location differentiation (near the mandible). Between the ocular nerves and the superior cervical ganglion synapse is a third-order or postganglionic lesion.

The parasympathetic and sympathetic nervous systems are the two elements of a cat’s autonomic nervous system. The sympathetic nervous system controls involuntary or automatic responses to fight or flight instincts. Pupil dilation, blinking, muscular tone, and heart rate are all part of this process. The compassionate nerve route, which runs from the brain to the chest, is somewhat lengthy. Damage to these nerves can cause the parasympathetic nervous system to take over the sympathetic nervous system’s duties at any point along the pathway.

->> Natural Health Supplements for Cats <<-

Horner’s Syndrome Symptoms in Cats

The cat eyes are involved in the majority of the visual indications of Horner’s Syndrome. The following are potential signs to look out for:

  • Ptosis (drooping eyelid)
  • Anisocoria is a type of anisocoria (unequal pupil size)
  • Hyperemia of the conjunctiva (protruding third eyelid)
  • A reduction in the width of the ocular opening
  • Sunken eye
  • On the affected side, warmth and redness around the eye and ear
  • Drooling a lot
  • Tilt of the head
  • Making a mistake

Horner’s Syndrome in Cats: What Causes It?

Trauma from a significant head, neck, or spinal cord injury is the most common cause of Horner’s Syndrome. Some cases of Horner’s Syndrome are idiopathic, meaning they have no evident cause for nerve problems. The following are some of the possible reasons.

  • Accident in a car
  • Injuries from a bite
  • Tumors in the chest, neck, brain, or spinal cord, whether benign or malignant
  • Disease of the retrobulbar (behind the eye)
  • Problems with the middle ear
  • Inflammation of the intervertebral discs
  • Clots in the blood

The parasympathetic nervous system ‘takes over’ when the sympathetic nervous system that supplies the eyes is damaged or dysfunctional, and signs of Horner’s Syndrome arise. The injury or malfunction might happen in the neck, ear, or eye. Blunt force trauma, such as caused by a car collision or a bite wound from another animal, can cause damage. Problems in the middle ear (otitis media), diseases within the eye or in the retrobulbar area (behind the eye), or tumors in the chest, neck, or brain are all possible causes of nerve damage or inflammation. “Many cats that develop Horner’s syndrome have a recent history of trauma, particularly being hit by a car.”

About half of all occurrences of Horner’s Syndrome in dogs are idiopathic, which means there is no recognized cause. In cats, on the other hand, a reason is almost always discovered, and idiopathic Horner’s Syndrome is quite unusual. Horner’s Syndrome affects many cats who have recently experienced trauma, such as being hit by an automobile.

Your veterinarian may propose a set of diagnostic tests to identify an underlying reason based on your cat’s recent history and other physical findings on inspection. A neurologic evaluation, an otoscopic examination (ear examination), and chest and neck X-rays are frequently included in the initial testing.

->> #1  Pet Insurance for Cats  (up to 90% Reimbursements) <<-

Horner’s Syndrome in Cats Diagnosis

The veterinarian will require your cat’s complete medical history to determine any underlying concerns. The cat will be given a thorough physical examination. Life-threatening problems will be handled first if the cat has suffered traumatic injuries. The veterinarian will perform a neurological evaluation and an otoscopic (ear) analysis to rule out any underlying health conditions. Horner’s Syndrome must be distinguished from other conditions with similar symptoms, such as ear infections, facial paralysis, and Key-Gaskell Syndrome.

To find any damage to the sympathetic nerve route, a phenylephrine test might be used. The damage is further away from the eye the longer it takes for the pupil to return to standard size following drop administration. To help uncover any health abnormalities in the body, entire blood work will be conducted, including a complete blood count (CBC) and a biochemical profile. Urinalysis can be used for this as well. Cerebrospinal fluid samples may be taken for testing if the spinal cord or brain injury is suspected.

Horner’s Syndrome in Cats: Treatment

Horner’s Syndrome is a collection of symptoms rather than a disease. If there is no underlying reason, the problem may resolve on its own. Symptoms can be treated to provide relief while the cat is experiencing them. If a primary health problem is identified, the Syndrome can be reversed with correct therapy.

Drops for the eyes

If the cat’s eyes are inflamed by Horner’s Syndrome’s many side effects, eye drops may be recommended to help relieve blinking and soothe and reduce any ocular ulcers. If the cat has an abnormally dilated pupil, phenylephrine drops can be administered to address the problem.

Surgical Extraction

If a tumor is found to be the source of the nerve damage, it may be removed to alleviate symptoms. Depending on the location of the fatal tumor, this may or may not be possible. Should surgery be conducted if the risk is less than the severity of the symptoms or if the tumors are malignant? The surgery is performed under general anesthesia.

Recovery of Horner’s Syndrome in Cats

If your cat already had surgery, make sure to follow all of the care instructions given to you at home. Check for swelling or bleeding at the incision site daily. If tumors are discovered to be the source of Horner’s Syndrome in your cat, the outlook may be bleak. However, if the Syndrome is caused by trauma and the cat survives all other injuries, there is a good possibility of recovery.

The nerve abnormalities may resolve on their own if the illness emerges quickly and no reason is recognized. However, it may take up to 16 weeks for this to happen. Horner’s Syndrome can be persistent in some instances due to irreversible damage; however, this is uncommon.

Are there any other conditions that resemble Horner’s Syndrome?

The only visible symptom in some instances is the elevation of the third eyelid. If your cat has facial paralysis (common with acute ear infections), severe dehydration, or Haw’s immobility, your veterinarian will rule out these possibilities. Cats with Haw’s paralysis will raise their third eyelids in response to illness, especially intestinal discomfort; the third eyelids may stay elevated for up to 4-6 weeks before returning to normal. Feline dysautonomia (Key-Gaskell syndrome) is an uncommon condition in cats that causes constricted pupils, elevated third eyelids, urine retention, constipation, and other issues due to severe sympathetic nervous system disruption.


Horner’s Syndrome is a nervous system condition that causes symptoms in the eyes due to a nerve failure. Horner’s Syndrome causes the pupil to shrink, the upper eyelid to droop, and the eyeball to recede further into the globe than average. The third eyelid can be seen from time to time, and it may be partially up over the eye. These symptoms usually affect one side only; however, they can affect both sides.

Nerve dysfunction/Syndrome Horner’s in cats can be caused by a variety of underlying disorders. Horner’s symptoms can appear if a problem develops anywhere along the nerve tracts that connect the brain and the eye. Sympathetic is the name given to the affected route. The term does not have the same meaning in this context as it does in everyday usage, but it does relate to a component of the body’s autonomic nervous system.

Horner’s Syndrome isn’t fatal, and it usually goes away on its own. Almost half of all cases of Horner’s Syndrome in cats have no evident cause (idiopathic). Recovery can take 16 weeks or longer in these cases because there is no identifiable cause to treat. Some cats never return to their former state. If the underlying cause of Horner’s is discovered, a treatment plan suited to the triggering disease will be implemented.

Horner’s Syndrome is linked to the following conditions:

  • Inflammation of the nerve tissues, infection of the middle ear
  • A traumatic event
  • Spinal tumors, brain stem tumors, and nerve tumors
Share on facebook
Share on twitter
Share on pinterest


Bringing your cat in for a vet visit can be a stressful experience for both you and your cat and that’s why we are committed to provide you with the answers …..



Leave a Comment

Your email address will not be published. Required fields are marked *