Primary conjunctivitis attributable to infectious pathogens is exceedingly rare in dogs In contrast to canine conjunctivitis, feline conjunctivitis is more commonly primary and attributable to infectious pathogens (viral, chlamydial, or bacterial). Bacterial conjunctivitis in dogs almost always occurs secondary to an underlying disease that alters normal resident conjunctival flora and favors bacterial proliferation.
In the case of allergic conjunctivitis the disease process begins by contact with airborne allergens. This leads to excessive redness and thickening of the inner eyelids, redness of the whites of the eyes, and sometimes excessive tearing. This resultant inflamed state leaves the eye predisposed to infection.
Left untreated, allergic conjunctivitis can lead to irritation that bothers the animal to the point that it begins to paw at the eye or rub it on ananimate objects, predisposing to corneal scratches or ulcers. This is a treatable disease but is not curable. Symptomatic treatment typically consists of a corticosteroid based ophthalmic drop or ointment formulation. Allergic conjunctivitis may wax or wane depending on the allergen (s) and its (their) prevalence during various times throughout the seasons.. In cases where it becomes a year round problem, allergy management, such as allergy testing and subsequent allergy injections, should be considered.
Roger L. Welton, DVM
Founder and Chief Editor, Web-DVM.net
President, Maybeck Animal Hospital
Article updated 8/29/2012