Conjunctivitis is an inflammation or infection of the conjunctiva, this is the tissue lining of the eyelids which is attached to the eyeball near the cornea. The conjunctiva becomes irritated due to allergies induced by pollens, grasses, etc., or infections caused by viruses, bacteria, or fungi. When the white part of the eyeball (sclera) is also inflamed, this condition is sometimes referred to as 'pink eye.' Conjunctivitis is one of the most common ailments affecting the eye of the dog.
What are the symptoms?
The symptoms of conjunctivitis vary depending on the cause. Both allergies and infections cause a severe red appearance of the conjunctiva. This is caused by fluid build-up and an increase in the size and number of blood vessels within the tissue. Both allergies and infections cause the eye to have a discharge or 'weep.'
The consistency of the discharge helps to determine its cause. Usually infections caused by bacteria, fungi, etc., have a thick yellow or greenish discharge, eyelids may actually stick together. This is caused from the accumulation of white blood cells excreted into the area in an effort to fight off the infection. This type of discharge is also a typical of a condition called keratoconjunctivitis sicca, ('dry eye,') which insufficient tears are produced. Allergies generally cause a clear or watery discharge. Regardless of the cause, a patient with conjunctivitis will often squint and/or keep the third eyelid partially covering the eyeball. Conjunctivitis is often painful, causing the dog to paw at or rub the eye against objects such as your leg or the carpet.
What are the risks?
Conjunctivitis is not life threatening. In advanced cases of the infection, the organisms can spread and affect other structures of the eye. Vision could become impaired. Infections or foreign bodies may cause corneal ulcers which are extremely serious conditions. Conjunctivitis can be a symptom of a more serious disease such as canine distemper. Some infections can be transmitted to other individuals or littermates. Allergies are not contagious and pose no threat to other dogs.
What is the management?
All cases of conjunctivitis should be treated as soon as detected. A culture and sensitivity test may be necessary to determine if bacteria are the cause, and if so, what medication should be used for the treatment. Scrapings of the conjunctiva can be made and examined to test for various other infections.
Eye drops or ointments are usually the treatments of choice. Eye drops are watery solutions that are applied every few hours; while ointments last longer they are usually only applied two to three times a day.
If an allergy is suspected, then various medications are available containing anti-inflammatories. If the cause is an infection, bactericidal or fungicidal ointments may be applied. Severe cases oral antibiotics are used as well as the topical preparations. The majority of cases will respond to treatment, but this may take one to two weeks to recover fully. Treatment is continued for several days once the eye has a normal appearance.
It's highly important not to use hydrocortisone based agents if a corneal ulcer is detected. Hydrocortisone, although very effective treatment at minimizing eye inflammation, it may actually hinder the healing or worsen of an ulcerated cornea.
What are the symptoms?
The eyes develop a thick, yellowish discharge. Infections are common as the lack of the tears allows bacterial organisms to overgrow onto the eye. Inadequate lubrication allows dust, pollen, etc., to accumulate. Resulting in the eyes to lose their ability to flush away foreign particles and protect themselves from bacteria. To diagnose a case of dry eye, a measurement of tear production is performed. Veterinarians will use a small piece of absorbent material. This small strip will be placed in the eye for approximately one minute; the tears are soaked up into the strip. The wet area is then measured and compared to normal results.
What are the risks?
If dry eye is left untreated, the patient suffers from painful and chronic eye infections. Repeated irritation of the cornea will result in severe scarring. Corneal ulceration can develop; this can lead on to blindness.
What is the management?
If the cause is identified, treatment is aimed at eliminating it. An evaluation to determine if an infection is present will be performed. A thorough history can reveal past infections that may have contributed to the damaging of the tear glands or the nerves. If sulfa drugs are being used these should be stopped at once. From clinical experience, it's very rare for a cause to be identified, in which case therapy is aimed at replacing the tears rather than trying to correct the cause.
Ointments or drops are most often used to treat this condition. In a few cases artificial tear solutions will also recommended.
In severe cases, surgery could be performed this would be the transplant of a salivary duct into the upper eyelid. Saliva would then drain into the eye, providing adequate lubrication. This procedure is very rare, but can sometimes be an option.