Overview of Canine Anterior Uveitis
Anterior uveitis, commonly referred to as just “uveitis”, is inflammation that affects the front or anterior part of the eye called the uvea, which is the dark tissue of the eye that contains blood vessels that can occur in dogs. The iris – the tissue that makes up the pupil – is typically involved. The posterior part of the eye may or may not be affected.
The causes of anterior uveitis include:
Immune-mediated conditions, in which the body attacks its own tissues
Infections from viruses, parasites, fungi, bacteria, rickettsia
Tumors or cancers
Trauma or injury to the eye
Metabolic disease elsewhere in the body that is affecting the eye
Idiopathic, which means the cause is unknown
Lens-induced, which is caused by the escape of lens protein into the eye fluid and is most frequently associated with cataracts
Older animals are more likely to have tumors, and indoor/outdoor pets are more likely to be exposed to infectious causes than pets housed strictly indoors. Also, in certain regions of the world specific infectious diseases are more common. Certain breeds of dogs are more likely to have immune-mediated anterior uveitis.
Anterior uveitis can be painful for your pet and may threaten vision. Just as important, this problem can also be a sign of a disease that is affecting the rest of the your dog’s body.
What to Watch For
Redness
Tearing
Squinting, especially in bright light
A small or unevenly shaped pupil
A cloudy or dull appearance in the front of the eye
An unevenly colored iris – a normal brown iris may be very red, darker brown than normal or have fluffy yellow/white areas
Diagnosis of Anterior Uveitis in Dogs
Diagnostic tests are needed to recognize anterior uveitis and exclude other diseases. Immune-mediated diseases may be difficult to diagnosis if they are confined only to the eye. All other causes of uveitis must often be excluded first. Tests may include:
Complete medical history and physical examination
A complete examination of the eye with an ophthalmoscope, including the external portion, the front segment of the inside of the eye, and the back part of the eye
Tonometry to measure the pressure within the eye
General blood tests, such as a complete blood count (CBC) and serum biochemical profile
Specific blood tests for immune diseases, infectious agents or other systemic diseases
Ultrasound, X-rays or aspirates, which are samples of fluid taken from inside the eye via a small needle
Treatment of Dogs with Anterior Uveitis
Treatments for anterior uveitis may include symptomatic, specific therapy and/or surgical intervention:
Symptomatic therapy, regardless of the cause of the anterior uveitis, is usually indicated. Topical treatments, like drops or ointments placed on the eye and medications taken by mouth, are designed to reduce pain and inflammation – like treating a headache with aspirin regardless of what is causing the headache.
Specific therapy is directed if a cause for the anterior uveitis has been determined. Appropriate topical and/or oral drugs are prescribed and may include an antibiotic, an anti-fungal drug, or a drug that reduces immune-mediated inflammation.
Surgical intervention. In situations where a tumor or secondary complications (such as glaucoma) are present and cannot be controlled with medications, it may be necessary to remove the eye surgically.
Home Care and Prevention
It is important that you follow your veterinarian’s instructions and learn to medicate your dog properly. It is not always easy to put medications into an animal’s eye, but it is imperative that the medications be given.
Examine your dog’s eyes every day and look for subtle changes. See your veterinarian for follow-up appointments to re-examine eye.
You have some control over your dog’s environment. Ask your veterinarian about your residential area so if ticks or fungal diseases are common, you will know what to look for.
Prevent trauma to eye; use caution when throwing balls or other objects.
Information In-depth for Dogs with Anterior Uveitis
A diagnosis of anterior uveitis simply means there is inflammation inside the eye. Numerous diseases can manifest as uveitis, so it can be difficult to diagnose the underlying cause. Several diseases mentioned below may be confined to the eye. However, in other cases, the condition may affect multiple parts of the body and the eye is but one aspect of disease. A dog may have either predominately ocular signs (those pertaining to the eye) or other signs such as weakness, lethargy, decreased appetite, coughing, fever or other problems.
Causes of Anterior Uveitis in Dogs
Infectious causes of anterior uveitis are numerous. Some common causes include:
Viral diseases such as distemper and adenovirus in young unvaccinated dogs.
Fungal diseases, like blastomycosis, histoplasmosis, cryptococcosis, coccidiomycosis and candidiasis. Different fungi are more common in certain regions of the world. Fungal diseases more frequently involve the posterior (back) segment of the eye as well as the front.
Rickettsial diseases. These include ehrlichiosis and Rocky Mountain spotted fever, which are both transmitted by ticks.
Other causes of anterior uveitis include:
Many different strains of bacteria and different types of toxins. Bacterial infections that are important causes of uveitis in the dog include Lyme disease and leptospirosis. Bacterial infections in other locations in the body, such as a uterine or kidney infection can also lead to inflammation inside the eye.
Tumors can cause anterior uveitis. The appearance varies, but the clinical signs of inflammation (uveitis) are common.
Lymphoma – The iris is generally thickened and there may be yellowish, white or pink discoloration.
Melanoma – The iris is generally thickened and darker brown than usual.
Adenoma or adenocarcinoma – Thick fluffy white areas can be seen through the pupil and sometimes the iris.
Metastatic tumors – Various tumor types can start elsewhere in the body and then move to the anterior uvea, although spread to the posterior uvea is much more common.
Trauma. Any type of injury to the head or eye can cause a uveitis because the uvea is filled with blood vessels, so inflammation and “bruising” can occur.
Metabolic diseases. Because the uvea is an extension of the body’s circulating blood system, many diseases that affect the body can have an impact on the eye. Examples include diabetes mellitus, hyperlipidemia, hypertension, and pancreatitis.
Lens-induced anterior uveitis can be caused when cataracts are present and are slowly leaking protein into the eye. This form of uveitis may be mild and chronic or can be more severe. The most severe form of acute lens-induced uveitis occurs when penetrating trauma to the eye disrupts the lens.
Uveitis can be associated with any of the following:
Immune-mediated diseases. In these diseases, the animal’s immune system “attacks” itself. These diseases tend to be more common in the dog, and the reaction may be confined to just eye tissues. Immune-mediated uveitis most often affects large breed dogs.
Uveodermatologic syndrome, also known as VKH or Vogt-Koyanagi-Harada-like syndrome, is a rare disease of dogs in which melanin (pigment) is attacked and destroyed by the immune system. In addition to anterior uveitis, dogs can have whitening of hair and skin, especially around the eyes, mouth and feet. It is most commonly seen in the oriental and sled-dog breeds, such as the Akita, Siberian husky, Samoyed, chow chow and Shetland sheepdog.
Other immune-mediated diseases may involve tissues elsewhere in the body. These include thrombocytopenia, in which platelets are being attacked and destroyed by the immune system, and hemolytic anemia, in which red blood cells are being attacked and destroyed by the immune system.
Several odd forms of uveitis occur in specific breeds of dogs. A uveitis called “pigmentary uveitis” occurs in golden retrievers. The cause of this condition is unknown. It is often associated with iris cysts and secondary glaucoma.
Secondary diseases complicating anterior uveitis include glaucoma, blindness, and lens luxation.
Diagnosis In-depth for Dogs with Anterior Uveitis
Diagnostic tests are needed to recognize anterior uveitis and exclude other diseases. These tests include:
Complete medical history and physical examination. Because anterior uveitis is commonly linked to a systemic disease, attention should be directed to the whole body, not just the eyes. The history that you give to your veterinarian can be helpful in determining exposure to infectious disease.
A complete examination of the eye. Your veterinarian or veterinary ophthalmologist will use various tools such as a direct and indirect ophthalmoscope, a tonometer, and a slit lamp. Among other things, an exam can determine if the inflammation affects one or both eyes; if the anterior and/or posterior segment of each eye is affected; if the lens is normal; and if there are any signs specific to the various causes, like pigment spattering in the eye of a golden retriever with pigmentary uveitis.
General blood tests to evaluate the red and white blood cells, platelets and general organ function like kidneys, pancreas and liver. These are basic tests to determine if the problem is confined to the eye or if it is affecting the rest of the body as well.
Specific blood tests directed toward finding an underlying cause. Blood tests can evaluate the immune system and specific organ function and can diagnose many infectious diseases.
Blood pressure measurement to determine if there is hypertension
Blood culture for bacteria if a widespread infection is suspected
Ultrasound of the eye. If an eye is so inflamed that an examination is difficult, an ultrasound of the eye can help locate a tumor or perhaps a lens that has either become a cataract or has fallen out of place in the eye.
An X-ray of the chest when the cause of uveitis can be traced to a tumors or fungal diseases
Ultrasound and X-rays of the rest of the body to identify and localize tumors that may be present in other organs of the body.
Treatment In-depth for Dogs with Anterior Uveitis
Treatments for anterior uveitis may include one or more of the following:
Symptomatic therapy, regardless of the cause. Symptomatic therapy includes general supportive care of a sick animal such as fluids, nutritional support, antibiotics and pain relief. Examples of symptomatic therapy for the eye may include:
Topical Medications (Drops and Ointments for the Eye)
Anti-inflammation medication. Steroids: prednisolone, dexamethasone, betamethasone. Non-steroidal drugs: flurbiprofen, diclofenac, suprofen.
Cycloplegic drugs such as atropine stabilize the blood vessels and dilate the pupil. This can provide comfort by paralyzing muscles of the iris, since they spasm when there is inflammation.
Oral and Injectable Medications for Uveitis
Anti-inflammatory medicine including corticosteroids (prednisone, dexamethasone) and nonsteroidal drugs like carprofen and aspirin. Oral corticosteroids are not used when infectious diseases are present. They are used primarily to treat immune-mediated disease.
Specific therapy is only used when there is a definitive diagnosis or high suspicion of a specific cause. Some examples:
Itraconazole is used for fungal diseases.
Doxycycline is used for tick-transmitted diseases, including Lyme disease.
Other antibiotics for certain other infections such as leptospirosis and toxoplasmosis.
Immune suppressants (prednisone, azathioprine) are used for immune-mediated diseases.
Insulin is administered to diabetic animals.
Surgical intervention is most common for tumors in the eye or when complications such as glaucoma cannot be controlled with medications. Frequently in these cases, the eye is surgically removed (enucleation). If a cataract or wound to the lens is responsible for the uveitis, then the entire lens may need to be removed.
Home Care for Dogs with Anterior Uveitis
Proper medication administration is essential. Dogs with anterior uveitis may need frequent medicating (such as drops to the eyes four times daily) and this can be difficult with our busy schedules. Speak to your veterinarian or veterinary ophthalmologist to work out a good plan.
Since pets can’t vocalize their problems, noticing even mild behavioral changes can be a sign that there is systemic disease and not just eye disease. Dogs that aren’t feeling well may stop eating or drinking, may hide under furniture, may not want to go outside or let you pet them around the head, may be depressed, and may sleep more than usual.
Become comfortable looking at your dog’s eyes. Inflammation inside of the eye can change rapidly and lead to secondary disease like glaucoma, so it is important to be able to recognize and to describe to your veterinarian or veterinary ophthalmologist what has changed. Frequent rechecks are generally necessary to determine a cause, adjust medications and monitor progression of the disease.
See your veterinarian as soon as possible if you notice a change in the eye, such as the eye becoming red, or your dog squinting or holding the eye closed, rubbing or pawing at the eye. Scratching at the eye may induce more self-trauma in dogs. An Elizabethan collar may be recommended.
