Uveitis – pronounced ‘yoo-vee-i-tis’ – refers to inflammation inside the eye. The disease can occur in dogs and cats of any age and breed. Patients with uveitis will show signs of pain, redness and cloudiness of the eye. There are many potential causes and sometimes the cause is never found. Prompt treatment is necessary to avoid severe long-term consequences; even blindness. In this article we will discuss the possible causes, symptoms, diagnosis and treatment of uveitis in pets.
What causes uveitis in animals?
The causes of uveitis are classified as being ocular (as a direct result of a disease or injury to the eye) or systemic (as a result of a disease elsewhere in the body).
Ocular causes of uveitis
- Corneal ulceration: Wound or an open sore on the outer surface of the eye
- Necrotising scleritis: Severe inflammation of the tissues surrounding the eye
- Deep keratitis: Inflammation of the surface of the cornea (the clear outermost layer of the eyeball)
- Cataracts
- Trauma to the eye, either penetrating injuries or blunt trauma
- Lens luxation: Dislocation of the lens (clear structure within the eye that focuses incoming light on the retina)
- Tumours inside the eye
Systemic causes of uveitis
- Infectious diseases:
- Septicaemia or toxaemia: Blood poisoning caused by bacterial infections
- Canine ehrlichiosis (tick disease)
- Toxocariasis (worms)
- Toxoplasmosis (parasites)
- Feline immunodeficiency virus (FIV)
- Feline leukaemia virus (FeLV)
- Feline infectious peritonitis (FIP)
- Canine distemper virus (CDV)
- Immune-mediated inflammatory disease
- Immune-mediated thrombocytopaenia (IMTP): The body’s immune system attacks blood platelets
- Metabolic disorders
- Diabetes mellitus
- Hyperlipidaemia (high blood fat levels)
- Systemic hypertension (high blood pressure)
- Cancer
One of these underlying causes will trigger an inflammatory cascade that can permanently damage the structures within the eye. Unfortunately, in the majority of cases a cause cannot be identified, so the disease is considered idiopathic (with no known cause) and treated symptomatically. See below for the various forms of treatment.
Symptoms of uveitis
The symptoms of uveitis are either acute symptoms (those that are seen when it initially starts) or chronic symptoms (those that occur as the inflammation continues over a period of days to weeks). The symptoms of uveitis can be seen in one or both eyes.
|
Acute Symptoms |
Chronic Symptoms |
|
Redness |
Deformity of the pupil |
|
Cloudiness |
Discolouration of the iris |
|
Pain (face rubbing, squinting or keeping the eye shut) |
Attachments of the pupil to other structures in the eye |
|
Discharge |
Cataracts |
|
Photophobia (avoiding bright light) |
Lens luxation |
|
Small or constricted pupils |
Swollen or shrunken eye |
|
Blood or pus within the eye |
Blindness |
If your pet is showing any discomfort, redness or discharge from the eye, make an appointment with the vet immediately.
How is uveitis diagnosed?
The veterinarian will start by taking a careful history of how your pet’s condition developed, followed by a thorough physical exam. Be sure to provide as much information to the vet as possible, as this will help to determine possible causes and assist with the diagnosis. A systematic ocular exam will be performed, which may include the following:
- Schirmer tear test: Determines if your pet’s tear glands are functioning adequately
- Ophthalmoscopic exam: Careful examination of all structures of the eye using magnification
- Fluorescein stain: Test to detect corneal ulceration
- Tonometry: Test for intraocular pressure
- Ocular ultrasound: To visualise internal structures of the eye
Depending on the findings, further specific tests on the eyes may need to be performed. Since uveitis can have systemic causes elsewhere in the body, it is important to do various blood and urine tests in order to identify a potential underlying cause.
If there is any indication of a specific condition that may be causing the uveitis, other tests may be necessary, such as chest X-rays, abdominal ultrasound or sample collection from other organs such as lymph nodes.
The veterinarian will be able to perform most of these tests; however, referral to an eye specialist is often recommended as some of the tests are more specialised in nature.
How do you treat uveitis in dogs?
If the underlying cause of the disease can be identified, it needs to be treated. However, often the cause is not found, so the vet offers treatment for the various symptoms.
The mainstay of treatment is the use of anti-inflammatory drugs such as corticosteroids or non-steroidal anti-inflammatory drugs. These can be given topically in the form of eye drops or systemically in the form of injections or tablets. As the disease is driven by the immune system, other immune-suppressive drugs may be needed.
If a bacterial infection is present in the eye or in other parts of the body, topical or systemic antibiotics will be given to treat the infection.
Mydriatics are drugs that are used topically to relieve the pain response (known as blepharospasm). The most commonly used mydriatic drug is atropine. Topical morphine may also be used for this purpose. Lubricant eye drops may be necessary to keep the cornea moist.
If concurrent conditions such as glaucoma (increased pressure inside the eyeball) are present, it will need to be addressed with additional treatments. Patients should be kept indoors in dark areas as they will be light sensitive. If the patient has a lens-associated uveitis due to a lens luxation or a cataract, they will need surgery to remove the lens.
Conclusion
Uveitis is a severe condition of the eye that can result in chronic glaucoma, blindness or the loss of one or both eyes. Many cases recur or relapse and will require ongoing treatment. If you see any abnormalities with your pet’s eyes, make an appointment to see the vet as soon as possible.
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