Canine Blepharitis

Eye injuries are becoming more and more common and more frequently diagnosed at vet clinics as technology advances and there's no option but to keep pace with it.

Blepharitis is no exception. Below, this site will explain what it involves, its symptoms, as well as diagnosis and treatment. Let's get started.

What Is Blepharitis?

Within inflammatory eyelid diseases, we can distinguish between diffuse eyelid inflammation (blepharitis) and localized inflammation (styes and chalazion). In this article, we'll focus on blepharitis.

Dogs' eyelid skin is the thinnest and finest of all, and this, combined with thin subcutaneous tissue, makes lesions in this area more or less severe.

Keep in mind that blepharitis can be primary in origin and only affect the eyelids, or be part of a generalized, systemic dermatological problem. That's why it's important to follow a rigorous protocol to reach a definitive diagnosis.

How Does Blepharitis Develop?

Several causative agents can trigger eyelid inflammation. These causes are:

• Parasitic: mites such as Sarcoptes and Demodex. Also Leishmania spp.
• Bacterial: in cases of juvenile pyoderma, bacterial blepharitis from Staphylococcus spp. and Streptococcus spp.
• Fungal: dermatophytosis caused, for example, by Microsporum canis.
• Allergic: food hypersensitivity, atopy, drug hypersensitivity…
• Immune-mediated: lupus erythematosus, pemphigus, etc.
• Nutritional: zinc-responsive dermatosis.
• Endocrine: hypothyroidism, Cushing's syndrome.
• Neoplastic: cutaneous lymphoma, mycosis fungoides.

Symptoms in Dogs With Blepharitis

Several signs related to blepharitis can appear. They don't all need to occur at once. But the most common fall into primary lesions (originating in the eyelids) and secondary ones (originating elsewhere but affecting the eyelids).

• Primary lesions: erythema (redness), alopecia (bald patches), papules (small bumps), nodules, pustules (pus-filled bumps), and depigmentation (loss of color).
• Secondary lesions: scales, erosions, ulcers, and scabs. In more chronic cases, hyperpigmentation is common.

Diagnosis

As with all conditions or vet visits, a diagnosis needs to be reached by following a series of steps as a guideline. First, the vet will want to gather as much detailed information as possible through a history or clinical record of the patient (since when, how it's progressed…).

Next, they'll perform a general clinical exam of our pet. Afterward, they'll specifically examine the blepharitis, checking whether it affects one or both eyes (uni- or bilateral) and how.

A clinical exam should establish whether there's a systemic disease present. At this point, it's important to establish the presence and location of other dermatological lesions that point the diagnosis toward lupus or other immune-mediated diseases, juvenile cellulitis, dermatomyositis, vasculitis, demodicosis, leishmaniasis, pyoderma…

Since in most cases the eyelid lesions observed don't allow for a clear diagnosis of what's causing the blepharitis, the vet will need to turn to additional tests.

For example:

• Skin scrapings to identify parasites.
• Microbiological cultures and antibiograms.
• Wood's lamp to observe lesions from certain fungi after applying fluorescence (some aren't detected this way).
• Biopsies when an immune-mediated origin is suspected. These biopsies shouldn't be taken right on the eyelid itself, since it could affect healing and its position, bothering the eye.
• Complete bloodwork when systemic infections are suspected, such as those caused by Leishmania.
• Cytology if there are masses or nodules, since this can help determine whether the lesion is tumor-related or inflammatory.
• Intradermal skin tests if allergies or atopy are suspected.
• Skin impressions allow for quick visualization of microorganisms. They're better observed under a microscope after a quick stain.

Is There a Treatment for Blepharitis?

Treatment needs to target the cause, meaning it needs to be etiological. The cause needs to be established first to put the most suitable treatment in place for each case. However, symptomatic treatment while awaiting a definitive diagnosis reduces clinical symptoms and makes our animal less bothered and more comfortable.

This should never be established at home by the owner, since, as we've seen, it can be due to multiple causes, and doing so could worsen the condition and make the prognosis worse by the time we do take it to the vet.

Likewise, for our animal's wellbeing, this condition shouldn't be left alone to see if it resolves on its own. A professional's opinion, that of the vet, will be essential for this and other conditions. Remember they've spent years training and specializing for exactly this.