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Conjunctivitis, Cats 199

Conjunctivitis, Cats Client Education
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VetBooks.ir Diseases and Disorders

BASIC INFORMATION
• “Red eye”
• Swelling around the eye DIAGNOSIS
Definition • May be unilateral or bilateral Diagnostic Overview
Inflammation of the mucous membranes • May be acute or chronic/intermittent A complete ophthalmic exam is essential
(conjunctiva) surrounding the eye • +/− Systemic signs (sneezing, anorexia, because numerous ocular disorders can cause
lethargy) secondary conjunctivitis. Most cases of chronic
Epidemiology conjunctivitis are treated empirically based on
SPECIES, AGE, SEX PHYSICAL EXAM FINDINGS history and exam because they are likely due to
Both sexes and all ages can be affected. Chla- • Blepharospasm FHV-1 (for which diagnostics are unreliable)
mydia felis usually occurs in cats < 1 year old • Ocular discharge (serous to mucopurulent, or C. felis (which can be treated empirically).
and is uncommon > 5 years old. mild to severe)
• Chemosis (especially C. felis) Differential Diagnosis
GENETICS, BREED PREDISPOSITION • Hyperemia Episcleral injection is engorgement of the scleral
C. felis appears to be more prevalent among • +/− Keratitis or corneal ulceration, depending blood vessels. It causes periocular redness and
purebred cats, but this may be biased by on cause (FHV-1, entropion, rarely distichia) occurs secondary to ophthalmic diseases such
exposure in catteries. • Whitish/yellow palpebral conjunctival as uveitis, glaucoma, and orbital disease.
nodules near eyelid margin (lipogranulo-
RISK FACTORS matous conjunctivitis) Initial Database
• Densely populated environments (shelters, • Other ocular disease (entropion, orbital Complete ophthalmic examination (p. 1137):
rescues, catteries, multi-cat households) disease, distichiasis, glaucoma, anterior • Schirmer tear test (normal > 15 mm/minute
predispose to infectious causes. uveitis) in dogs, varies in cats)
• UV light may contribute to lipogranuloma- • Sneezing, nasal discharge (FHV-1, less ○ Can be artificially decreased in cats due
tous conjunctivitis because cases usually occur commonly C. felis) to stress
in light-colored cats (white, orange). • Lymphadenopathy (C. felis, infectious or • Fluorescein dye application
neoplastic causes of uveitis) • Intraocular pressure (normal: 10-20 mm Hg)
CONTAGION AND ZOONOSIS • Fever (C. felis, FCV, infectious or inflam- • Examination of the eyelid margin and
• Many of the common causes are infectious matory causes of uveitis) palpebral conjunctiva with magnification
and can spread from cat to cat (feline her- • Oral ulceration (FCV) and a good light source
pesvirus 1 [FHV-1], C. felis, feline calicivirus • Examination of the cornea
[FCV]). Etiology and Pathophysiology • Fundic examination
• C. felis has a low potential for zoonosis, with Conjunctivitis is often what causes a diseased
immunocompromised people at highest risk. eye to appear red and can have primary causes Advanced or Confirmatory Testing
• Thelazia spp infect humans by the vector fly or occur secondary to numerous other ocular • Polymerase chain reaction (PCR) testing:
but not through contact with infected cats. diseases. recommended for C. felis and Mycoplasma,
Primary causes: unreliable for FHV-1 (p. 464)
GEOGRAPHY AND SEASONALITY • Infectious • Conjunctival cytology: diagnostic for pro-
• Thelazia callipaeda (Europe, Asia) and ○ Viral: FHV-1, FCV liferative keratoconjunctivitis (eosinophilic)
Thelazia californiensis (western United ○ Bacterial: C. felis, +/− Mycoplasma felis, (p. 568), rarely can see inclusion bodies with
States) infections may be seasonal because +/− Mycoplasma gatae C. felis and Mycoplasma
they involve a fly intermediate host (Musca • Parasitic: T. callipaeda, T. californiensis • Conjunctival cultures and biopsy are rarely
spp, Fannia spp, Phortica variegata, Amiota (nematodes of conjunctival sac), Cuterebra used. Mycoplasma and C. felis are difficult to
spp). spp culture. The conjunctiva of normal cats is not
• Allergic conjunctivitis (rare in cats) may have • Immune-mediated sterile, and Mycoplasma can be cultured from
a seasonal component. ○ Allergic conjunctivitis (rare in cats) asymptomatic cats. Asymptomatic shedding
○ Proliferative keratoconjunctivitis (eosino- of C. felis can occur. Histopathology confirms
ASSOCIATED DISORDERS philic) lipogranulomatous conjunctivitis but is not
• Symblepharon, keratitis, and corneal ulcer- • Inflammatory routinely done because exam findings are
ation with FHV-1 ○ Lipogranulomatous conjunctivitis characteristic.
• Some cats with lipogranulomatous con- • Trauma
junctivitis are concurrently diagnosed with • Chemical burn TREATMENT
squamous cell carcinoma of the eyelid skin • Environmental irritants (e.g., smoke, sand)
adjacent to the conjunctival lesions. • Foreign bodies Treatment Overview
• Therapeutic radiation Treatments depend on the underlying cause.
Clinical Presentation Secondary to other ocular disease: The goals of treatment are to relieve clinical
DISEASE FORMS/SUBTYPES • Corneal ulceration signs and prevent spread of disease.
• Acute versus chronic • Entropion
• Primary disease versus recrudescent disease • Distichiasis (rare) Acute General Treatment
(FHV-1) • Tear film abnormalities (keratoconjunctivitis • FHV-1: For conjunctivitis secondary to
• Primary versus secondary causes sicca, qualitative disorders) FHV-1 without keratitis, antiviral therapy
• Uveitis is usually not warranted unless the cat is
HISTORY, CHIEF COMPLAINT • Glaucoma immunocompromised and the conjunctivitis
• Blepharospasm • Orbital disease severe or chronic (p. 464).
• Ocular discharge • Blepharitis • FCV: (p. 141)

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