What causes uveitis in cats

Overview

Uveitis in cats refers to inflammation of the uvea, which is the vascular layer of the eye that includes the iris, ciliary body, and choroid. This inflammation can affect one or both eyes and can manifest acutely or chronically. Recognizing the signs and understanding the causes of uveitis is crucial for prompt diagnosis and treatment, as untreated uveitis can lead to serious complications such as glaucoma, cataracts, and blindness.

Causes of Uveitis in Cats

The causes of uveitis in cats are diverse and often require thorough investigation by a veterinarian. They can be broadly categorized as follows:

Infectious Causes

Infections are among the most common triggers for uveitis in cats. These can be caused by a variety of pathogens:

• Viral Infections: Feline Immunodeficiency Virus (FIV) and Feline Leukemia Virus (FeLV) are well-known causes. These viruses weaken the immune system, making cats more susceptible to secondary infections and directly affecting ocular tissues. Other viruses like Feline Infectious Peritonitis (FIP) can also cause uveitis.
• Bacterial Infections: While less common than viral causes, bacterial infections can arise from systemic infections or direct inoculation into the eye (e.g., from trauma).
• Fungal Infections: Systemic fungal infections, such as cryptococcosis or blastomycosis, can spread to the eyes and cause inflammation.
• Parasitic Infections: Certain parasites, like Toxoplasma gondii (toxoplasmosis), can infect ocular tissues and lead to uveitis.

Immune-Mediated Diseases

In these conditions, the cat's own immune system mistakenly attacks its healthy eye tissues. This can occur as a primary condition or secondary to other diseases. Autoimmune disorders can affect various parts of the uvea.

Neoplasia (Cancer)

Cancer is a significant consideration in feline uveitis, especially in older cats. This can include:

• Primary Ocular Tumors: Tumors originating within the eye itself, such as lymphoma or melanoma.
• Metastatic Cancer: Cancer that has spread to the eye from another part of the body. Lymphoma is a common metastatic cancer that affects the eyes of cats.

Trauma

Direct injury to the eye, whether from a fight with another animal, an accident, or even self-trauma due to itching, can cause inflammation of the uvea. Blunt force trauma or penetrating injuries can both lead to uveitis.

Systemic Diseases

Uveitis can be a manifestation of broader health issues affecting the cat's entire body. Examples include:

• Systemic Hypertension: High blood pressure can cause damage to the blood vessels in the eye, leading to inflammation and bleeding.
• Kidney Disease: Chronic kidney disease is often associated with hypertension in cats, which can, in turn, affect the eyes.
• Other Inflammatory Conditions: Certain systemic inflammatory diseases can also manifest with ocular signs.

Idiopathic Uveitis

In some cases, despite extensive diagnostic testing, the specific cause of uveitis cannot be identified. This is termed idiopathic uveitis.

Diagnosis and Treatment

Diagnosing the cause of uveitis is critical. A veterinarian will perform a thorough ophthalmic examination, which may include measuring intraocular pressure, examining the anterior and posterior segments of the eye, and checking for signs of systemic illness. Diagnostic tests can include blood work (to check for infections like FIV, FeLV, or systemic diseases), urinalysis, and sometimes fine-needle aspirates or biopsies if cancer is suspected. Treatment is directed at the underlying cause and may involve anti-inflammatory medications (topical or systemic), antibiotics, antivirals, or chemotherapy, depending on the diagnosis. Prompt veterinary care is essential to preserve vision.