Optic Neuritis in Dogs

The optic nerve is the essence of what makes up vision. Without it, we wouldn’t be able to see! Unfortunately, it is possible for this nerve to become damaged. For pets and humans alike, this will cause vision to become impaired or cease because the main structure for transmitting your eye’s signals to the brain is damaged.

There are many reasons your pet can develop this condition. Some are more serious than others, especially if they are from an underlying disease. Fortunately, this condition can usually be treated, but sometimes it leaves your pet with permanently affected vision.

Optic nerve swelling, or optic neuritis, is inflammation of the optic nerve. This is the structure responsible for transmitting electrical signals from the retina to the brain.

Because this condition is on the eyes, it will be very apparent that something is wrong. Your pet may have symptoms suddenly, or if the optic neuritis is formed from an underlying condition, it can show up gradually.

The symptoms of optic neuritis are few. They usually will be:

• Dilated pupils
• Optic nerve head is swollen
• Sudden blindness
• Pain with eye movement
• Tender eyes and areas around the eyes
• Decreased depth perception

If you notice any of these symptoms, definitely schedule your pet in to see their veterinarian as soon as possible. Your veterinarian will most likely refer you to an ophthalmology specialist for further testing on your pet’s eyes.

Unlike the symptoms, there are several reasons why your dog may have a damaged optic nerve. Most of them are due to an underlying disease such as toxoplasmosis, Neosporosis, multiple sclerosis (MS), or a vitamin A deficiency. Optic neuritis is actually the number one symptom when diagnosing MS; it will usually be diagnosed after finding optic nerve swelling. Other causes could be:

• Infection
• Trauma
• Cancer
• Toxin ingestion (not common with canines)

With inflammatory brain diseases, such as Neosporosis, this is usually a last resort symptom. Any sudden change in eyesight is never a good sign, so it is important to know your dog’s eye health.

A Vitamin A deficiency can be prevented and treated by giving your pet more fish, liver, and vegetables in their diet. If your pet has optic neuritis due to a deficiency, however, it is extreme and should be discussed with your veterinarian.

Diagnosing this condition is not always easy. Optic neuritis is not always an obvious case; the specialist will have to perform many examinations to correctly diagnose the issue.

This will usually begin with simple eye tests, such as checking pupil dilation and if your pet can see certain objects. If this fails, then the specialists will schedule an electroretinogram (ERG). This procedure is a closer look at the outer retina. Because this test must be absolutely spot-on, your pet will have to be put under an anesthetic, so they don’t move about.

Other tests that will help determine if it is optic neuritis are an MRI and brain fluid samples (CSF). The CSF test helps determine if there are any fluids or substances in the eye that shouldn’t be there, such as glucose, blood, or proteins.

The treatment for optic neuritis is fairly simple. A specialist should give your pet intravenous steroids as this will reduce the risk of them developing MS later on by 50%. There are oral steroids, but the risks are obviously higher. Pets who receive these steroids start to have improved health from anywhere between a few days to a few weeks. The only exception is for dogs who may have a more serious condition.

Your veterinarian may also prescribe antibiotics and a topical treatment. These will just help clear and fight off any infections that may develop.

While this condition can permanently affect your pet’s vision, the prognosis is good. Swelling of the nerves can damage vision, causing blindness, however, early treatment and uncomplicated cases have better results.

You should keep your pet on bed rest and most likely invest in an Elizabethan collar, so they can’t touch their eyes. Playing, walks, and trips outside should be kept to a minimum and heavily supervised. Your veterinarian may also require a few check-ins to see how your pet is feeling.