What is blepharitis and what are the signs?
Blepharitis means inflammation of the eyelid.
Blepharitis can affect one or both eyes. The affected eyelid will usually be red, swollen, and itchy. The cat may squint or blink spasmodically (called blepharospasm). Often the cat will scratch or rub at its face or eyelids leading to secondary trauma to the surrounding tissues. There may also be a discharge from the eye that may be clear, mucoid, or purulent (containing pus). If the inflammation has been present for a significant amount of time, there may also be loss of pigment or hair.
The skin covering the eyelids may have dry crusts or flakes on its surface and small papules or pustules (pimples) may develop on the surface. The papules, pustules, and crusts may be single or multiple. One or more meibomian glands (glands that help lubricate the eyes) along the margin of the eyelid may become swollen. In more severe cases, the inflammation may spread and include conjunctivitis (inflammation of the conjunctiva) or keratitis (inflammation of the cornea).
"The skin covering the eyelids may have dry crusts or flakes on its surface..."
What causes blepharitis?
Any condition that can cause irritation of the eyelids can lead to blepharitis. Common causes of blepharitis include congenital abnormalities, allergies, infections (bacteria, fungal, viral, parasites, or protozoal), tumors, trauma, and occasionally other inflammatory disorders.
The most common congenital eyelid abnormality that can predispose a cat to developing blepharitis is entropion, a condition in which the edges of the eyelid turn inwards and rub against the cornea. Cats with a short flat face or prominent facial folds are more prone to develop this condition, especially if the cat also has lagophthalmos (bulging eyes).
Allergies to insect bites, inhalant allergens or food may also cause blepharitis.
Cats that have been infected with feline herpes virus-1 (FHV-1) may develop chronic blepharitis as a secondary problem. Bacterial infections may cause localized abscesses of glands in the eyelids or generalized infections of the eyelids. In some cases, infection with Staphylococcus bacteria (staph) may lead to an allergic reaction, called Staphylococcus hypersensitivity.
Other causes of blepharitis include tumors, trauma to the eyelids, diseases such as diabetes mellitus, environmental irritants such as tobacco smoke, and eosinophilic granuloma complex (for more information on this condition, see the handout "Eosinophilic Granuloma Complex in Cats").
In some cases, an underlying cause cannot be determined; this is called idiopathic blepharitis.
Are any cats predisposed to develop blepharitis?
Persian, Himalayan, and Burmese cats are more likely to develop blepharitis due to their facial conformation, (flattened faces, and prominent folds of skin between the nose and eyes). These breeds of cats may have lagophthalmos (bulging eyes) and they are predisposed to lower eyelid entropion.
White cats of any breed are predisposed to development of squamous cell carcinoma, a malignant tumor which can develop anywhere on the skin or mucous membranes, including the eyelids. For more information eye tumors in cats, see the handouts "Eyelid, Conjunctival, and Peri-ocular Tumors" and "Squamous Cell Carcinoma in Cats".
How is blepharitis diagnosed?
Your veterinarian will conduct an eye examination to determine the extent of the eyelid involvement. The eye examination will often include testing such as a Schirmer tear test to assess the tear production in the eye. Your veterinarian may collect samples of cells or secretions to look for evidence of an infectious agent such as feline herpes virus or bacterial organisms. Samples may be sent to a diagnostic laboratory for viral identification or bacterial culture and sensitivity testing to determine the type of treatment that is needed.
If your veterinarian suspects an allergy, further testing may be necessary to determine the specific allergic cause.
For suspect tumors, a biopsy will be necessary to determine the nature of the tumor. If there is no obvious reason for the blepharitis, your veterinarian may recommend blood tests to look for evidence of an underlying disease.
What is the treatment for blepharitis?
Your veterinarian may recommend short-term symptomatic treatment for the inflammation, such as application of warm compresses for 5-15 minutes several times per day and removal of any discharge from the eye.
However, any specific treatment for blepharitis will depend on the underlying cause of the disorder. Surgery is the treatment of choice for correcting eyelid abnormalities or removing tumors. In some cases, this may require referral to a specialist. Bacterial infections will be treated with topical antibacterial ointments or drops. Chronic herpes virus infections may be managed with antiviral drops during flare ups. Allergic disorders may be controlled with antihistamines, corticosteroids, or other immunosuppressant medications along with avoidance of the allergen. If a food allergy is diagnosed, the condition may be manageable with diet alone. Blepharitis that is secondary to an endocrine (hormone) disorder will be treated symptomatically until the endocrine problem is controlled.
What is the prognosis for recovery?
The prognosis depends entirely on the cause of the blepharitis. If a congenital abnormality is responsible for the problem and it is surgically corrected, the prognosis is excellent. If the blepharitis is caused by a squamous cell carcinoma, it may not be possible to completely remove the tumor. However, cancer treatment is a rapidly evolving field and combination treatments using other forms of cancer therapy may prove to be useful for managing this problem. Cats infected with the feline herpes virus will remain carriers for the rest of their life and may have relapses on occasion, especially if they are stressed. For many cats with blepharitis, the underlying condition can be controlled with medical management but it often cannot be cured.