{"id":23161,"date":"2021-04-09T13:15:46","date_gmt":"2021-04-09T13:15:46","guid":{"rendered":"https:\/\/todaysveterinarypractice.com\/?p=23161"},"modified":"2025-10-06T12:59:44","modified_gmt":"2025-10-06T12:59:44","slug":"diagnosing-treating-and-managing-causes-of-conjunctivitis-in-dogs-and-cats","status":"publish","type":"post","link":"https:\/\/navc.sitepreview.app\/todaysveterinarypractice.com\/ophthalmology\/conjunctivitis-in-dogs-and-cats\/","title":{"rendered":"Diagnosing, Treating, and Managing Causes of Conjunctivitis in Dogs and Cats"},"content":{"rendered":"

Conjunctivitis is a common ocular disorder in cats and dogs. Its etiologies are numerous and include primary conjunctival diseases as well as extraocular, intraocular, and systemic conditions. Clinical signs of conjunctivitis are frequently nonspecific and may be similar despite diverse etiologies.\u00a0<\/span><\/span><\/p>\n

Although the primary causes of conjunctivitis are common, severe ocular diseases and potentially life-threatening systemic conditions can initially present as conjunctivitis. Failure to consider both local and systemic causes of conjunctivitis can have serious consequences for ocular and general health; therefore, a methodical and thorough clinical approach to conjunctivitis should always be followed.<\/span><\/p>\n

Basic Conjunctival Anatomy and Physiology<\/h2>\n

The conjunctiva is the mucous membrane covering the posterior aspect of the eyelids, palpebral and bulbar surfaces of the nictitating membrane, and anterior portion of the globe (<\/span>FIGURE 1<\/span><\/strong>). The conjunctiva is composed of nonkeratinized, stratified epithelium and underlying connective tissue; the latter is called the substantia propria.<\/i> Mucin-producing goblet cells reside in the conjunctival epithelium, and the substantia propria contains vessels, nerves, and lymphoid tissue. The rich vascular network, loose arrangement of the substantia propria, and resident lymphoid tissue contribute to the conjunctiva\u2019s ability to respond rapidly, and often dramatically, to insults.\u00a0<\/span><\/span><\/p>\n

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Illustration: Kip Carter<\/p><\/div>\n

On the anterior surface of the globe, the bulbar conjunctiva covers the episclera and sclera proper. The sclera proper is the thickest layer of the sclera and is composed of irregular collagen fibers, fibroblasts, and melanocytes. The episclera is the most superficial layer of the sclera and is a thin, collagenous, vascular tissue. The anatomic proximity of the bulbar conjunctiva and these scleral tissues results in frequent conjunctival involvement with diseases of the episclera and sclera proper.<\/span><\/p>\n

Clinical Signs of Conjunctivitis<\/h2>\n

Conjunctivitis is invariably associated with a combination of the clinical signs listed in <\/span>BOX 1<\/span><\/strong>. Epiphora, the overflow of serous tears, results from excessive production or inadequate nasolacrimal drainage. Chemosis appears as conjunctival swelling and is the clinical manifestation of conjunctival edema caused by increased vascular permeability with fluid extravasation into the substantia propria (<\/span>FIGURE 2<\/span><\/strong>). Hyperemia is red conjunctival discoloration (often referred to as \u201cred eye\u201d) and is a clinically observable <\/span>manifestation of conjunctival vasodilation and increased blood flow within the conjunctiva (<\/span>FIGURE 3<\/span><\/strong>). Ocular discomfort and pruritus most commonly manifest as blepharospasm and periocular rubbing.<\/span><\/p>\n

BOX 1 Clinical Signs of Conjunctivitis<\/div>
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