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Conjunctivitis in Dogs

What is conjunctivitis?

The conjunctiva is the lining tissue that covers the globe of the eye (the eyeball) and lines the eyelids and the third eyelid. Conjunctivitis refers to inflammation of this tissue. Most cases of conjunctivitis are characterized by ocular discharge and swollen tissue around the eye.

 

What are the clinical signs associated with conjunctivitis?pannus_2009

The most common clinical signs of conjunctivitis include discharge from the eyes (watery, mucoid or mucopurulent), squinting or excessive blinking, and redness or swelling around the eyes. Conjunctivitis often involves both eyes, but only one eye may be affected in certain conditions. Conjunctivitis may occur with other clinical signs such as nasal discharge, sneezing or coughing.

 

What causes conjunctivitis?

The most common causes of conjunctivitis include bacterial and viral infections, allergies, hereditary conditions, and tumors. Conjunctivitis may be a secondary symptom of another eye disease.

Bacterial infections that are not associated with another condition such as keratoconjunctivitis sicca ("dry eye") are rare in adult dogs. However, puppies can have bacterial infections even before their eyes are open.

Specific causes of conjunctivitis include:

 

How is conjunctivitis diagnosed?kcs-2_2009

The main goal of diagnosis is to determine if the conjunctivitis is a primary or secondary problem, if there is additional disease or damage to the eye, if the condition is allergic, or if it involves the tissues of the eye itself (sclera). In order to differentiate many of these conditions, a complete and detailed ophthalmic examination must be performed. This will include detailed examination of the adnexa or surrounding eye structures (eyelids, eyelashes, tear ducts, third eyelid, etc.), tear production tests (Schirmer tear production test), corneal stain tests to ensure that the cornea is not damaged, and measurement of intra-ocular pressure to rule out glaucoma or uveitis. Additional tests and procedures that may be performed include nasolacrimal duct flushing, bacterial culture and sensitivity tests, conjunctival cytology or biopsy and allergy testing.

 

How is conjunctivitis treated?

"Treatment...may include both topical and oral or systemic medications."

Treatment is directed at the specific cause and may include both topical and oral or systemic medications. Topical gentamicin, tobramycin, chloramphenicol, oxytetracycline, ciprofloxacin or triple-antibiotic ophthalmic ointments and solutions are commonly prescribed. Some patients will receive medications containing anti-inflammatory agents such as ophthalmic prednisolone or dexamethasone. In dogs that have secondary conjunctivitis, oral antibiotics or anti-inflammatory medications may also be used. Patients diagnosed with KCS will usually require medications such as cyclosporine or tacrolimus to stimulate tear-production. Patients with eyelid or eyelash abnormalities will require surgical correction.

 

Will my dog recover from conjunctivitis?

Most dogs have an excellent prognosis in most cases of conjunctivitis. Severe, chronic or recurrent conjunctivitis may have a guarded prognosis, depending on the definitive diagnosis. Conditions such as KCS and immune-mediated disorders may require lifelong therapy.

Ernest Ward, DVM
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