Bacterial, Fungal, Viral and Parasitic Conjunctivitis
Conjunctivitis, also known as "red eye," is an inflammation of the eye's protective mucous membrane, the conjunctiva. This membrane lines the inside of the eyelids and the surface of the eyeball as far as the cornea. Conjunctivitis is probably the most common eye disorder that owners see.
The condition often occurs when the conjunctiva is irritated by a hair or a foreign body. If both eyes are inflamed. however, it may be an indication of more serious problems elsewhere, either within the eyeball itself or in other parts of the body. Allergic conjunctivitis, associated with sneezing (rhinitis), appears to be increasing in dogs. As well as causing local inflammation, conjunctiva is associated with various discharges that give clues to the cause of the problem. For example, if the eye is infected, the discharge becomes yellowish-green.
DISCHARGES
A clear, colorless discharge usually indicates that the eye is suffering form a physical or allergic irritation. Dust, wind blowing in the face, and cold air may all trigger a watery discharge from both eyes. Allergens such as pollen can do the same, but allergy is often accompanied by as itchiness that makes the dog rub its face. Watery discharge from a single eye is usually caused by a foreign body.
A jelly-like discharge of mucus may result from irritation by a foreign body or from an infection. Both of these problems will trigger increased mucus production from the conjunctiva. A yellowish-green discharge is pus, which means that infection is present and must be treated without delay.
If infectious conjunctivitis is suspected, a conjunctival swab is performed. In
dogs, swabs are sent for bacterial culture and sensitivity testing. In cats, if Chlamydophila or feline herpesvirus infection is suspected, conjunctival and oral swabs are advised and must be placed in appropriate transport media before transport to the laboratory.
BACTERIAL AND FUNGAL CONJUNCTIVITIS
Like the skin, the conjunctiva acts as host to many normal bacteria and fungi. Injuries, foreign bodies in the eye, viral infections, or, most important of all, a reduction in tear production will allow some of these bacteria and fungi to grow rapidly. As a result, they cause an infection.
Signs of one of these infections include redness, a yellowish-green discharge, and crusting of the eyelids. Dogs may blink, squint slightly, or paw at and rub their eyes. In neonatal conjunctivitis, a newborn pup may suffer an infection before or after the eyelids have separated, usually between 10 and 14 days. Pups with fused eyelids (ankyloblepharon) are prone to neonatal conjunctivitis. The eyelids bulge or appear swollen, and there may be a discharge. If your pup is affected, you must let your vet know at once in order to prevent more serious disease.
Diagnosis & Treatment
It is very important to determine the cause of bacterial or fungal conjunctivitis. The infection itself is diagnosed by culture or sensitivity tests and is treated with the appropriate topical antibiotics. To treat the condition, you can use sterile saline eyewash to flush the eye several times a day. If there is a crust, soak it in warm water, then loosen and remove it with a warm, damp washcloth.
VIRAL CONJUNCTIVITIS
The viruses that cause canine distemper and hepatitis also predispose the eyes to developing bacterial conjunctivitis. Distemper, in particular, is associated with reduced tear production and the subsequent development of dry eye. Many eye signs of canine distemper have been reported, including acute and chronic conjunctivitis, keratoconjunctivitis sicca (KCS), anterior uveitis, retinochoroiditis, optic neuritis and cortical blindness.
Acute conjunctivitis is found in the early stages of distemper in conjunction with systemic signs. Initially the ocular discharge is serous. Over 7–10 days the discharge becomes pus-filled as secondary bacterial conjunctivitis develops. Acute and chronic keratoconjunctivitis sicca (KCS), dry eye syndrome have been reported with canine distemper. In most dogs, spontaneous recovery and normal of tear production has been reported to occur over 4–8 weeks, but chronic keratoconjunctivitis may result, presumably depending on the degree of lacrimal gland damage during infection. Symptomatic treatment includes topical tear replacements and topical broad-spectrum antibacterials. If tear production does not return in 2 or 3 months, parotid duct transposition may be necessary.
Canine adenovirus: A conjunctivitis may accompany anterior uveitis in canine adenovirus infections.
<== Melting Corneal Ulceration
Bacterial disease A wide range of bacterial species has been implicated
in conjunctivitis, but Gram-positive organisms pre-dominate, most notably Staphylococcus and Streptococcus spp. Fusidic acid, chloramphenicol and neomycin
are active against these species and are usually first-line treatment for canine bacterial conjunctivitis. Pseudomonas aeruginosa is a Gram-negative bacterium
that may cause conjunctivitis. It may also infect the cornea if there is overlying epithelial damage, and melting corneal ulceration. Gentamicin or tobramycin are active against Pseudomonas spp. If melting corneal ulceration is present, specialist advice
should be sought urgently.
Diagnosis & Treatment
An early diagnosis of distemper is sometimes made by examining a conjunctival scraping for viral particles. Secondary bacterial infection is treated with appropriate antibiotics. The eyes are kept moist with saline eye wash and monitored carefully for the possible development of dry eye.
PARASITIC CONJUNCTIVITIS
In the western United States there is a parasitic worm, Thelazia californiensis, that can inhabit the space between the eyelids and the eye (the conjunctival sac). The presence of this worm causes conjunctivitis known as thelaziasis.
Diagnosis & Treatment
Locating the worm by eye examination confirms thelaziasis. The vet will use a drop of local anesthetic and removes the worm with forceps. Alternatively, the eye is flushed with an antiparasitic solution specially prepared for the eye.
Go Pets America recommends seeking the advice of your local veterinarian for the most appropriate vaccination program and for the diagnosis and treatment of your pet's health problems. For vaccination requirements please contact your state and local licensing authorities.
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