Overview of Anterior Uveitis in Cats
Anterior 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. 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, and protozoa
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
The eyes of cats are affected by more viruses than other animals. Such viruses include feline leukemia virus, feline immunodeficiency virus, and feline infectious peritonitis virus. The protozoal parasite, toxoplasmosis, is one of the most common causes of anterior uveitis in the cat.
Older cats 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.
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 pet’s body.
What to Watch For
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 yellow-green iris may be very red, develop brown areas or have spots within it
Diagnosis of Anterior Uveitis in Cats
Diagnostic tests are needed to recognize anterior uveitis, and exclude other diseases. 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, which is a measurement of 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 Anterior Uveitis in Cats
Treatments for anterior uveitis may include symptomatic or specific therapy and 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 oral medications 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 anti-fungal drug or a drug that reduces immune mediated inflammation.
Surgical intervention. In situations where there is a tumor or secondary complications (such as glaucoma) that cannot be controlled with medications, surgery to remove the eye may be necessary.
Home Care and Prevention
It is important that you follow your veterinarian’s instructions and learn to medicate your pet properly. It is not always easy to put medications into an animal’s eye, but it is imperative the medications be given.
Examine your pet’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 pet’s environment. Cats can be protected from many of the infectious diseases that cause anterior uveitis by keeping them indoors.
Prevent trauma to eye; use caution when throwing balls or other objects.
In-Depth Information on Anterior Uveitis in Cats
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. Some of the 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 pet may have either predominately ocular signs (those pertaining to the eye) or multisystemic signs such as weakness, lethargy, decreased appetite, coughing, fever or other problems.
Infectious causes of anterior uveitis are numerous. Some common causes include:
Viral diseases. FIV (feline immunodeficiency virus), FeLV (feline leukemia virus), FIP (feline infectious peritonitis virus).
Protozoal disease. Toxoplasmosis is a protozoan parasite that is more common in the cat than the dog . It is potentially a zoonotic disease, meaning that people can acquire this disease from cats that are shedding the parasite in bowel movements. If your cat is diagnosed with toxoplasmosis, it is essential to ask your veterinarian and physician about the risk. This is especially important for pregnant women, young children, elderly or immune-compromised individuals.
Fungal diseases like blastomycosis, histoplasmosis, cryptococcosis, coccidiodomycosis, candidiasis. Different fungi are more common in dogs versus cats and in certain regions of the world. Cryptococcosis and histoplasmosis occur more often in the cat. Fungal diseases often involve the posterior (back) segment of the eye as well as the front.
Many different strains of bacteria and different types of toxins. Sometimes a remote infection such as a uterine or kidney infection may lead to inflammation inside the eye. Many tick borne diseases cause uveitis in the dog, but rarely do so in the cat.
Other causes of anterior uveitis include:
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 focal yellowish, white or pink discoloration.
Melanoma – The iris is generally thickened and darker brown than usual.
Adenoma or adenocarcinoma – Often appears as a pink white mass peaking through the pupil from behind the iris.
Trauma. Any type of injury to the head or eye can cause a uveitis because the uvea contains numerous blood vessels, so secondary 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 hypertension, elevated circulating proteins, and uremia.
Lens-induced anterior uveitis may develop when cataracts are present. A cataract is an opacity of the lens. Lens-induced uveitis is more common in the dog, but may occur in the cat if some sort of penetrating trauma to the eye disrupts the lens.
Immune-mediated diseases. In these diseases, the animal’s immune system “attacks” itself. These diseases tend to occur primarily in the dog, and include such conditions as thrombocytopenia, in which platelets are being attacked and destroyed, and hemolytic anemia, in which red blood cells are being attacked and destroyed by the immune system. Any uveitis associated with these conditions is a secondary effect.
Secondary diseases complicating anterior uveitis may include glaucoma, cataract formation, blindness, and lens luxation.
In-Depth Information on Diagnosis of Anterior Uveitis in Cats
Diagnostic tests are needed to diagnose 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.
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 for determining 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, specific organ function and can diagnose many of the infectious diseases.
Blood pressure measurement to determine if hypertension is present
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 involve other organs in the body.
In-Depth Information on Treatment of Anterior Uveitis in Cats
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-inflammatory medication. Steroids: prednisolone, dexamethasone, betamethasone. Non-steroidal drugs: flurbiprofen, diclofenac, suprofen.
Cycloplegic drugs such as atropine stabilize the blood vessels and dilate the pupil. These drugs provide comfort by paralyzing muscles in the eye that spasm when inflammation is present.
Oral and Injectable Medications
Anti-inflammatory medicine including corticosteroids (prednisone, dexamethasone) and nonsteroidal drugs like carprofen and aspirin. Oral steroids are not used in the presence of any of the infectious agents.
Specific therapy is 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.
Clindamycin is used for toxoplasmosis.
Immune suppressants (prednisone, azathioprine) are used for immune-mediated diseases.
Surgical intervention is usually reserved for the treatment of tumors in the eye or for complications such as glaucoma that cannot be controlled with medications. Frequently in these cases, the eye is surgically removed (enucleation).
Home Care for Anterior Uveitis in Cats
Proper medication administration is essential. Cats 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. Cats that aren’t feeling well may stop eating or drinking, may hide under furniture, may not let you pet them, may act depressed, or may sleep more than usual.
Become comfortable looking at your pet’s eyes. Inflammation inside of the eye can rapidly change 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 looking red and irritated, or if the cat is squinting and holding the eye closed, or if your cat is scratching at it.