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Conjunctivitis, Dogs 201

ophthalmic conditions and some systemic • +/− Lymphoid follicles (typically most • Fluorescein dye application
diseases. numerous in the conjunctival fornix or • Complete exam of the eyelids, anterior
VetBooks.ir Synonym • +/− Conjunctival petechiae or ulcerations • Physical exam and history to evaluate for Diseases and Disorders
bulbar surface of the nictitating membrane)
segment, and posterior segment of both eyes
concurrent systemic disease
Pink eye
(CHV-1)
Epidemiology • +/− Other signs of ocular disease such as Advanced or Confirmatory Testing
pigmentary keratitis, entropion, trichiasis,
SPECIES, AGE, SEX etc. • Conjunctival biopsy and histopathologic
No sex predisposition. Young dogs are predis- evaluation may be indicated in unusual or
posed to follicular conjunctivitis. Etiology and Pathophysiology persistent cases.
Primary: • Conjunctival cytology
GENETICS, BREED PREDISPOSITION • Environmental or mechanical irritation • Bacterial or fungal culture (rarely rewarding)
Breed predisposition: • Follicular conjunctivitis • Polymerase chain reaction (PCR) assay or
• Deep conjunctival pockets (deep medial • Allergies (atopy, food allergy, contact allergy) serology for infectious diseases based on
canthal pocket syndrome): dolichocephalic are also a common cause of conjunctivitis; history and systemic signs
breeds conjunctivitis is reported in 60% of dogs
• Ectropion, entropion, or other conforma- with atopic dermatitis. TREATMENT
tional abnormalities of the eyelids: bulldogs, • Immune-mediated: pannus
cocker spaniels (p. 296) • Infectious primary conjunctivitis in dogs is rare Therapeutic Overview
• Keratoconjunctivitis sicca (KCS) (p. 568) but may include viral infection (CHV-1), or Determining the underlying cause of con-
• Pannus: German shepherds (p. 748) parasitic infection (Onchocerca lupi, Thelazia). junctivitis is critical to direct therapy. Goals
• Atopy (p. 91) ○ Bacterial conjunctivitis is typically associ- of treatment are to alleviate ocular discomfort,
ated with other conditions such as KCS. eliminate or ameliorate the underlying cause
RISK FACTORS Secondary: (e.g., establish normal tear production with
• Outdoor activities (environmental allergens, • Other ocular causes of red eye: lacrimomimetic therapy in cases of KCS,
parasitic) ○ Adnexal abnormalities address atopy with systemic medications/food
• Contact with chemicals or irritants (includ- ○ Tear film disorders trial), and eliminate underlying infection if
ing ophthalmic drugs such as neomycin or ○ Corneal ulceration present.
pilocarpine) ○ Keratitis
• Unvaccinated dogs, contact with dogs ○ Glaucoma Acute General Treatment
infected with canine herpesvirus 1 (CHV-1) ○ Uveitis Allergic, follicular, immune-mediated, or
and canine distemper virus • Conjunctivitis secondary to systemic infec- environmental conjunctivitis:
tion is rare but may include viral infection • Topical steroid or steroid/antibiotic
CONTAGION AND ZOONOSIS (canine distemper virus, CAV-1, CAV-2), combinations (e.g., neomycin, polymyxin,
Most cases of conjunctivitis in dogs are not bacterial infection (rickettsial, periocular, or dexamethasone or plain dexamethasone
contagious. Selected cases may be contagious, retrobulbar cellulitis), or parasitic infection 0.1% solution or ointment) q 6-8h until
including viral conjunctivitis (CHV-1, canine (Leishmania). the symptoms resolve, and then taper
distemper virus, canine adenovirus 1 and 2 • Neoplastic causes are rare: lymphosarcoma • Limit exposure to irritants such as dust, wind,
[CAV-1, CAV-2]) is the most common. smoke, or contact irritants
• Systemic noninfectious diseases such as sys- • Elizabethan collar may be required to limit
ASSOCIATED DISORDERS temic histiocytosis or ligneous conjunctivitis self-trauma
KCS, qualitative tear film deficiency, blepha- associated with a plasminogen deficiency are • Irrigate the conjunctival fornices with
ritis, uveitis, glaucoma, pannus, atopy, eyelid rare. saline q 12h to remove ocular discharge,
abnormalities (entropion, ectropion, trichiasis, allergens, and irritants; long-term irrigation
ectopic cilia), orbital inflammation DIAGNOSIS indicated for dogs with medial canthal pocket
Clinical Presentation Diagnostic Overview syndrome in conjunction with prn topical
steroids
DISEASE FORMS/SUBTYPES Diagnostics should center on determining • Address underlying allergies.
• Unilateral or bilateral whether there is an ocular cause for the Conjunctivitis secondary to an underlying
• Acute versus chronic conjunctivitis. cause:
• Primary: follicular, immune-mediated • Treat the associated ocular condition (e.g.,
(pannus), bacterial (rare), parasitic Differential Diagnosis topical cyclosporine or tacrolimus for KCS).
• Secondary: associated with other ocular (e.g., Conjunctivitis must be differentiated from other • Treat underlying infection or neoplasia
KCS) or systemic disorders (atopy, distemper) causes of red eye: • Topical antiviral therapy is indicated for
• Anterior uveitis CHV-1; idoxuridine 0.1% or trifluridine
HISTORY, CHIEF COMPLAINT • Glaucoma 1% solutions 6-8 times daily for 48 hours,
• Mucoid or mucopurulent ocular discharge • KCS then 4 times daily; cidofovir 0.5% solution
• “Red eye” • Corneal ulceration q 12h all for 1 week past resolution
• Painful eye • Keratitis • O. lupi is treated with medical therapy
• Ocular rubbing/pruritus • Episcleritis/scleritis (melarsomine IM, tetracycline antibiotics
• Orbital disease PO, ivermectin SQ or PO) +/− surgical
PHYSICAL EXAM FINDINGS removal of the nematodes; Thelazia infections
• Conjunctival hyperemia Initial Database may be treated with manual removal of the
• Mucoid or mucopurulent ocular discharge Complete ophthalmic exam (p. 1137): nematodes and anthelmintics.
(may be pronounced) • Schirmer tear test (normal > 15 mm/min
• +/− Chemosis in dogs) Chronic Treatment
• +/− Blepharospasm • Tonometry (normal is > 15 mm Hg and • Lifelong therapy is indicated for most cases
• +/− Elevated nictitating membrane < 25 mm Hg) of KCS and pannus.

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