Episcleritis in Dogs

The location of the nodule can vary and can include the iris, eyelid, oral mucocutaneous junction (the area between the skin and the moist lining of the oral cavity), or the nictitans, the translucent inner eyelid, sometimes called the third eyelid. In rare cases, episcleritis can cause the deadening of eye tissues, and can progress into more serious intraocular disease, such as retinal detachment. In many affected dogs, a long term treatment plan is needed.

Episcleritis is an inflammatory disease affecting the eye. Solitary nodules are seen on the eye and accompanying areas, often with inflammation around the nodule itself. Symptoms can be similar to other conditions of the eye, and can be positively confirmed through diagnostic testing.

Symptoms of episcleritis include:

• Red eye
• Irritated eye
• Inflammation in eye
• Alteration in clarity of eye
• Nodules or lesions on eye, often pink to tan in color
• Nodules or lesions on the nictitans, or the translucent inner eyelid, or other areas of the eye, often pink to tan in color 

Types 

Episcleritis can be differentiated into two forms:

• Diffuse - Also called simple episcleritis, it can affect one or both eyes and is most common in Golden Retrievers and Cocker Spaniels. It manifests as an elevated lesion in the limbic area, between the cornea and the white of the eye, with accompanying inflammation in both tissues.
• Nodular – Also called nodular granulomatous episclerokeratitis, nodular fasciitis, proliferative conjunctivitis, pseudotumor, fibrous histiocytoma, or collie granuloma, this condition usually affects one eye and is most common in Collie breeds. It manifests as a raised pink mass in the cornea or nictitating membrane, the translucent inner eyelid.

The direct cause of episcleritis isn’t always clear, but it is believed to be immune-mediated. Some accepted causes of this condition include:

• Ocular disease
• Auto-immune disease
• Toxoplasmosis, an infection of the Toxoplasma gondii organism
• Breed predisposition (Golden Retrievers, Cocker Spaniels, Collies, Airedales)

Your veterinarian will conduct a complete eye exam, taking into considerations visual appearance of the eye, medical history, and any other symptoms present. Symptoms of episcleritis are similar to other conditions and infections, so testing is conducted to make a positive diagnosis. 

A biopsy is conducted to differentiate episcleritis from any other kind of abnormal growth, usually with anesthesia. An exam of the biopsied tissue can discover any infectious agents or foreign materials, such as the Toxoplasma gondii organism. Other tests for toxoplasmosis include blood counts, serum panels, and immunohistochemical staining for antigens. Surgical debulking to remove as much of the nodule as possible may be performed in conjunction with the biopsy.

Biopsy and Surgery

Once a biopsy has been performed, antibiotics and steroid medications are often prescribed to prevent bacterial infection and address the inflammation. A re-evaluation is conducted to assess the condition, usually in about 4 weeks. If needed, treatment will continue or change.

Severe cases may need surgery to remove the lesions with cryotherapy, or a freezing procedure, and can often induce remission. If it wasn’t done previously, surgical debulking of the lesion may be performed.

Drug Treatment

Corticosteroids are the main treatment for episcleritis. Topical and oral corticosteroids, such as prednisone, are often used in combination with immunosuppressive drugs, such as oral azathioprine, mycophenolate mofetil, or cyclosporine. Several weeks of treatments can cause a remission of symptoms. Doses are usually reduced over time. 

An alternative course of treatment that has had success with some dogs includes oral tetracycline and niacinamide (Vitamin B3) taken over many weeks to months. Doses are decreased once improvement is seen.

Remission

Once episcleritis goes into remission, treatments can be tapered gradually over several months. While some cases will see the episcleritis completely resolved once treatment has ended, other dogs may need a long-term treatment plan to maintain remission. This is often done with immunosuppressive medications, such as azathioprine, mycophenolate mofetil, or cyclosporine in low doses.

Side effects

Side effects from mycophenolate mofetil or cyclosporine can include vomiting, diarrhea, and anorexia. Effects seen from azathioprine can be more severe and include liver disease, bone marrow suppression, and pancreatitis. With any drug that suppresses the immune system, there is always an increased risk of developing infections and some cancers.

Toxoplasmosis

Treatment for toxoplasmosis includes oral antibiotics and antiprotozoal medications over several weeks.

In many cases, recovery is quick after topical steroid treatments or surgical removal of the nodule. You may have special instructions after surgery that can include cleaning and changing bandages. You will most likely have medications to administer at home, and your dog may need future veterinary visits to test for the success of the therapy. Be sure to monitor your dog for any unwanted side effects and report those immediately to your veterinarian.