Blepharitis in dogs

Overview

Eyelids protect the surface

Closing lids protect the cornea from drying and injury. The inner surface is lined by conjunctiva, a thin membrane. A thin lipid layer covers the more watery tear layer beneath. Meibomian glands along the margins secrete oily material into the film. This slows evaporation. Bacterial inflammation can affect one gland or extend across the lid.

Surrounding skin can also become inflamed. A German 102-dog population had concurrent periocular inflammation in 69%. Dogs were selected for blepharitis with confirmed skin disease. Only 2.9% had blepharitis without other skin changes. Twenty-two had lid inflammation without periocular involvement but lesions elsewhere. Six could not be distinguished as lid-only versus periocular cases.

Causes

Skin disease, infection and parasites

Periocular itching and redness can accompany atopic dermatitis. Food allergy or insect sting reactions can also affect lids. Allergic skin disease underlay 52% of German cases. Infection or parasites accounted for 21.5%. Autoimmune disease accounted for 17.7%. Tumours accounted for 4.9%.

Demodex mites can multiply in follicles, producing red, hairless patches. Parasite-related blepharitis can involve surrounding skin. Bacteria can infect a gland and cause a local stye. Ruptured Meibomian glands can release oily secretions into tissue. Inflammation around leaked material can form a firm lump called a chalazion.

Lid changes and puppy facial disease

Inward-rolling lids can rub the surface and predispose to blepharitis. Gland tumours can irritate the surface. Juvenile sterile granulomatous dermatitis can swell the face and ear flaps. Some cases remain unexplained despite investigations.

Glaucoma drops were suspected in periocular dermatitis in two atopic Shih Tzus. Signs began 94 and 104 days after starting eye medication.

Risk factors

Brachycephalic dogs were proportionately overrepresented in the German group. Large eyelid openings can prevent complete closure and predispose to surface injury. Prominent nasal fold hairs can contact the cornea in very short-muzzled dogs. Medial lower lid inversion can also alter tear duct opening position. Tears may then overflow onto the cheek instead of draining normally. Extra lashes can rub if directed towards the eye.

Atopic periocular signs can occur alongside ear or paw inflammation. Most atopic dogs first show signs between six months and three years. Juvenile sterile granulomatous dermatitis typically occurs between three weeks and four months.

Typical symptoms

One or both eyes can be affected. Inflamed lids can itch. Surface irritation can cause rapid blinking or squinting.

• Red eyelid skin.
• Thickening through swelling.
• Hair loss on or around lids.
• Crusted margins.
• Rubbing with a paw or against surfaces.
• Watery or purulent discharge.

Hair loss or thinning affected 97% of the 102 German patients. Redness occurred in 93%. Swelling occurred in 50%. Crusts occurred in 39.2%.

Persistent inflammation can reduce skin pigment. Small bumps or pustules can form. Local swelling can affect one or several margin glands. Puppies with sudden sterile granulomatous facial inflammation can also have enlarged mandibular nodes. Ear flap skin may weep concurrently.

Complications and consequences

Tear film and cornea

Gland dysfunction can weaken the lipid layer. Tears can evaporate faster. The German study found reduced production in 10 of 53 measured dogs. Another study included 81 dogs with ocular surface disease. Gland dysfunction affected 105 of 150 eyes, or 70%. Tear test results were not statistically associated with dysfunction.

Rubbing can injure the cornea. Scratching an inflamed lid can damage surrounding skin too. Severe inflammation can extend to conjunctiva. It can also reach the cornea. Chronic dryness can cloud the cornea and impair vision. Inward lid rubbing can cause painful ulceration.

Diagnosis at the vet

Eye and skin examination

The vet assesses lids and surfaces of both eyes. Margins are checked for rubbing lashes. Wider skin signs prompt examination elsewhere for underlying disease. Suspected bacteria can be sampled from beneath a crust, for example.

Schirmer testing measures tear production. It has been recommended for every dog with blepharitis. Fluorescein identifies superficial corneal injury. Infrared imaging can investigate suspected gland dysfunction.

One report described a two-year-old crossbreed with blepharitis and sebaceous adenitis. Its Meibomian glands appeared shorter and thinner on imaging.

Samples distinguish causes

Cytology examines a sample for inflammatory cells and bacteria. Skin scrapings can be examined for Demodex mites. Plucked hairs can be examined when scraping near the eye is difficult. Culture and susceptibility guide bacterial treatment. Suspicious eyelid lumps can be biopsied. Histology can also identify sterile inflammation resembling a tumour. Unexplained local disease may warrant blood tests for underlying conditions.

Treatment

Protecting the lid and treating the cause

The vet chooses treatment according to the cause of blepharitis. A vet-recommended warm compress can provide temporary relief. Sterile eye wash can remove discharge before prescribed topical treatment. A collar can protect the surface against repeated scratching.

Confirmed local bacterial infection may need a prescribed ocular antibiotic ointment or drops. Deep bacterial skin infection treatment can follow culture and susceptibility results. Demodex inflammation needs effective antiparasitic medication. Surgery can correct abnormal lid position rubbing the cornea. An irritating tumour can be removed surgically. Prognosis is good for congenital lid malposition-associated inflammation if correction succeeds. Some unexplained cases can be controlled with topical eye medication.

Allergic and sterile inflammation

Allergy treatment and avoiding triggers can help allergic blepharitis. Juvenile sterile granulomatous dermatitis needs immunosuppressive treatment. Concurrent bacterial skin infection can require sample-guided treatment. Corticosteroid eye medicines are unsuitable with corneal ulcers.

A four-dog series of rare sterile periocular granulomatous inflammation found resolution in all after immunosuppression. None recurred during average follow-up of 17.3 months.

The crossbreed with sebaceous adenitis improved over three weeks. Gland ducts remained obstructed on imaging.

Prevention

Managing underlying allergy reduces associated symptoms. Tobacco smoke can irritate lids. Long hair contacting the surface can be trimmed to stop rubbing. Gentle handling around the eyes from puppyhood can ease later prescribed drop application. Check periocular skin more closely during seasonal atopic flare-ups. Report persistent tearing even without crusts.

Important for dog owners

Record whether one or both eyes and other skin areas are affected. Report current eye medicines before new treatment. Do not use human or another pet's medicines without veterinary advice. Keep the dropper tip away from the eye and lid. Wash hands before and afterwards to prevent contamination and spread. Contact the treating vet for increased redness or inflammation after application.

Frequently asked questions

Is blepharitis the same as conjunctivitis?

Blepharitis affects lids with redness, swelling or crusts, for example. Conjunctivitis affects the membrane covering the surface and inner lids. The same dog can have inflammation of both the eyelid and the conjunctiva. With blepharitis, skin changes may also be visible elsewhere on the body.

What if there is a lump on the lid?

A local lump can be an inflamed eyelid gland or a tumour, for example. The vet examines where the lump lies and whether it touches the surface of the eye. If a tumour is suspected, a tissue sample can help establish the nature of the lump. A lump can also form through an inflammatory reaction to secretions leaking from a gland into eyelid tissue.

Are antibiotics always needed?

The choice of treatment depends on what is causing the inflammation. An antiparasitic medicine is used to treat Demodex mites. Examination of a cell sample can identify inflammation caused by bacteria. When necessary, culture results help the vet select an antibiotic effective against the bacteria. Treatment of sterile granulomatous inflammation may instead be based on suppressing the immune response.

Can I clean eyelids at home?

Discharge around the eye can be removed with a sterile wash intended for use around eyes. If the eye is painful or cloudy, your dog needs a prompt veterinary examination. Keep the wash bottle tip away from the eye and other surfaces. Wash hands before handling periocular skin or applying drops.

Why can blepharitis recur?

If atopy underlies the inflammation, your dog may develop eyelid signs during flare-ups of the skin disease. Abnormal lid position can maintain irritation if the lid continues to rub the eye. Repeated bacterial infections prompt investigation of the underlying cause that predisposes the dog to inflammation. At the same appointment, the vet can measure tear production and examine the surface of the eye.