# Horners Syndrome in dogs



## FEWill (Sep 2, 2009)

Horners Syndrome in dogs is a very unusual condition that can affect any dog, at any age, and has no one single cause. However, when and if it does occur in your dog, it can be a very frightening experience. But as bad as it can appear, it is not actually painful to your dog. The most frightening aspect of this syndrome is the changing of your dogs eyes.

What is it?

Horners Syndrome in dogs is not a single symptom, but rather a grouping of signs that occur when very specific muscle in your dogs face lose control or the ability to be stimulated by nerves. In most all cases, it will involve the sympathetic nerves, which are part of your dogs sympathetic nervous system and are critical for contracting blood vessels in your pet.

A syndrome is almost always a collection of symptoms that have very little meaning or impact until they all start to fit together. A syndrome is often confused with a diagnosis, or an answer to an actual cause, but it is not an actual diagnosis. It is, however, a situation where the actual potential number of causes become limited to the extent that your veterinarian has a much better chance at actually developing a diagnosis, and as such, can find a treatment.

Your dogs body has several functions that are controlled by their nervous system that act without your dogs knowledge or control. Examples of this would be the heart as well as the respiratory system, sweat and other secretions, and the amounts that are released. It also includes pupil dilation and constriction. This is referred to as the automatic system and it is part of your dogs nervous system.

It is divided into two parts; the sympathetic nervous system and the parasympathetic system. The parasympathetic system maintains normalcy, while the sympathetic system will prepare your dogs body for a fight of some kind or an escape from something that is threatening them.

There are some changes that may occur or become stimulated by the sympathetic system that will include an increase in sweating, dilated pupils, as well as an increase in the flow of blood to your dogs muscles. In some cases it can also cause an increased heart rate. These systems work in complete harmony in your dog until the sympathetic system becomes damaged, either by an injury or an underlying condition. Once this happens, only the parasympathetic system remains active, and the result is referred to as Horners

Syndrome.

Causes:

Finding and diagnosing the actual cause of Horners syndrome in dogs can be very difficult, simply because there may be several potential causes. The first cause is very common with syndromes, and is called Idiopathic, meaning that the cause will never be known. It may also be the result of a car accident that has caused trauma in your dogs head, neck, or their chest. It may not be a severe trauma and you may never know that it actually occurred, but it is just enough to throw off this very delicate harmony that exists between the two systems.

It may also be caused by some type of a bite wound from a wild animal or another dog, or it may be the result of an infection in your dogs middle ear. However, even though it is not actually painful for your dog, it may have very sinister underlying causes. These would include an Inter-vertebral disk disease that is starting to form, a disease in your dogs orbit, which is the area behind their eye, or it may be the result of cancer. Brain cancer or chest cancer can very easily throw off this balance.

Symptoms:

As troubling as Horners syndrome in dogs is to actually diagnose or find the actual cause, it has very distinct symptoms that will occur in almost every case. When more than a couple of these symptoms surface at the same time, the rest should follow very quickly as they are all classic symptoms of this syndrome.

The first is referred to as Miosis, which is where your dogs pupil constricts to a much smaller size. This constriction is a normal reaction to increased light and will return to full size when they adjust. However, in this case they do not adjust as the automatic nerve messages have become disturbed. Once this occurs, there will be a protrusion of your dogs third eyelid. This is also common in pink eye or red eye, but is also one of the five classic symptoms with this syndrome.

The next symptom is called ptosis, which is drooping of the upper eyelid of your dog. But perhaps the most familiar symptom, called enophthalmos, is the best known of all the symptoms of Horners syndrome. With this symptom, your dogs eye will sink into their socket and can be very frightening the first time you witness it. The final of the classic five symptoms is a dilation of the blood vessels in your dogs face. This syndrome will almost exclusively be on only one side of your dogs face, and all of the symptoms, including this one, will stay on the affected side.

To confirm that your dogs has Horners syndrome, touch the effected side of their face; if it is feels much warmer than the other side, it is confirmed.

Can it be diagnosed?

The answer is yes. If your dog exhibits all five of these symptoms, you have just diagnosed it yourself. The difficult part is now up to your veterinarian in trying to find the actual cause of this syndrome. They will have to do a complete neurological exam, perform x-rays, chemistry panels, as well as a complete blood count. In some cases they may also have to do a CAT scan or a MRI before they can get a complete answer, if they can.

It most every case, your veterinarian will also have to administer Epinephrine into your dogs eyes to assist them in finding the actual location of the injury. This is done by measuring the time between the first dosage and the actual dilation of the pupil. If it is an injury to your dogs nerves that is outside of their brain, it will cause dilation within 20 minutes. If it is lesion or the injury that is in the brain or the spinal column, it will take much longer for dilation to occur. This is a very fascinating testing process and should be one of the first tests you ask your veterinarian to perform if your dog does indeed show all five symptoms.

Treatments:

What is even more amazing about this syndrome is that unless your veterinarian can actually find the actual cause, such as a bite wound or middle ear infection, there is no treatment needed. Eye drops will generally be given to relieve the clinical signs, but it will not help the pain because there is no pain. In most cases, it will simply go away on its own.

Summary:

Horners syndrome in dogs in most every case looks much more severe than it actually is. It will usually resolve itself between six to eight weeks and your dog will appear as normal as ever. But it is still recommend having the Epinephrine tests just for your peace of mind.

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## LouJ69 (Feb 28, 2009)

My baby girl, alpha was just diagnosed with this today. Noticed a difference in size between her 2 pupils...although I actually thought that the bigger pupil was the one with the problems. Brought her to the vet who diagnosed Horners but referred us to an opthalmologic specialist just in case. He said that she had Horner's, the signs being the smaller pupil and a slight droop in her upper eyelid. He also said that she was about 30% of the way along the spectrum (ie. 100% being problems with third eyelid etc.) and that it may appear to get worse before it gets better. The cause of it is idiopathic as alpha has never had any head or spinal trauma. It could take anywhere from 1-4 months to get back to normal, but that it was nothing to worry about. As he said, once the whites of her eyes stay white then it's fine. Massaging her face around the affected area may help to stimulate the nerves, so she'll be getting plenty of face rubs in the future! He compared it to Bells Palsy in humans which makes it a lot easier to explain to people.
Have to say, he was a really great vet...he explained every little thing and showed us her optic nerve, the blood vessels etc. Really took the time to examine her properly and talk to us in detail. He even gave us a discount of 30 as we had already paid our own vet 45 earlier in the day.


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## Rusty123 (Sep 18, 2012)

Hi we would like some help about horner syndrome. Our 10 year old Male labrador started with what we thought was an allergic reaction to something in his eye area about 6months ago, so we bathed the eye a few times a day everyday. After a couple of weeks the eye became worse, much more enflamed and bulging and went from a red colour to green. So we bacame very concerned but we thought one of our over excited spaniels had swiped him round his face whilst playing.. So we took him to our vets who diagnosed horners syndrome and prescribed Maxitrol eyedrops, one drop in the eye three times a day.. After a couple of weeks the redness went down and it wasnt as bulging, but still looked very sore and covering almost half of his eye. We have repeatedly taken him back to the vets who have said nothing can be done about it and it 'should clear up within a few weeks'.. Well that never happened and now it is covering 3/4 of his eye, bright red blood coloured and bulging out of his eye. It looks frankly disgusting and uncomfortable for our poor boy but he doesnt seem bothered about it its just we are!! . Please if anyone can help shed some light then we would much appreciate it. Thankyou


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