Dog Dry Eye

" Dog dry eye is a common term used to specifically describe a condition called keratoconjunctivitis sicca (aslo called KCS or Canine Dry Eye Syndrome). This condition is related to the inadequate produciotn of tears and the tear flow in the eyes. Canine dry eye problems result in severe dog eye infections and the progressive worsening of eye health. Identified causes of dry eye in dogs are injuries and trauma to the nictitans gland, long term use of sulfonamides, and autoimmune diseases. Sometimes the condition is inherited, which is referred to as being congenital. Diagnosis involves clinical examination, history and measurement of dog tear production and flow in the eye. The exact cause is usually not possible to diagnose. Treatment is done with the help of antibiotics (to prevent secondary infections), supportive care and regular eye cleaning. Severe and recurring canine dry eye cases are treated surgically with different approaches. ."

Causes of Dog Dry Eye:

Keratoconjunctivitis sicca or dog dry eye occurs if tears are not produced in adequate volume to lubricate and protect the surface of the dog eyes. In dogs, the most common cause of canine dry eye are autoimmune diseases. These diseases cause inflammation and sensitivity in the nictitans gland, thus the functionality of this gland is disturbed and the condition ends up with eye dryness.

Some drugs such as sulfanomides, if administered for long periods of time or in excessive doses, such as when treating canine distemper, causes insufficiency of nictitans gland function. This is an adverse effect of this drug.

Another cause of dog dry eye is trauma or injury to the third eyelid and nictitans gland. This trauma or injury is either caused by an accident or during surgery. If the dog third eyelids are damaged or removed by mistake during surgery, this will certainly affect nictitans gland efficacy (function). Similarly, in accidents if the third eyelids or when the nictitans gland is damaged or injured, it leads to the occurrence of canine dry eye.

In some cases, dry eye in dogs occurs as secondary (caused by) other primary dog eye problems such as infections, mechanical pressure over the nictitans gland etc. This is a relatively uncommon but possible cause of the condition.

Symptoms of Dog Dry Eye:

Clinically, canine dry eye is identified by yellow and viscous discharge, which in the latter stages of the condition contain pus mixed with the discharge. Dog eye infections, especially of the conjunctiva and cornea are typically related to this condition. The dog eye appears dried and due to continuous bacterial growth and irritation, other symptoms such as redness and partial to complete loss of eye function can be noticed. Tears possess antibacterial properties, thus bacterial growth occurs in excess due to infections, lesions and inflammation.

Additionally, tears also wipe out pollutants, dust and foreign particles from the eye surface. In the absence of tears, these foreign allergenic factors can cause irritation and redness along with secondary eye problems related to the dog dry eye condition.

In severe conditions, due to dryness and canine eye infections, symptoms may diffuse into the cornea, eye ball and up to the nerve supply. Infections in these parts of the eye will certainly cause the degeneration and partial or complete loss of eye function.

Other symptoms include rubbing of the eyes, corneal ulcers, cloudy eyes, and behavioral change such as lethargy (acting tired). 

Diagnosis of Dog Dry Eye:

In most cases, the exact cause of dry eye in dogs remains vieled or hard to determine. Clinical features of the condition and a dog's history can help in making an assessment of the possible cause, otherwise available laboratory procedures can only confirm the presence of the condition, not its cause.

Clinical symptoms and history of the condition such as any trauma, surgery, administration of sulfanomides and possible hypersensitivity can represent a possible cause.

In the laboratory, to confirm inadequate production and the flow of tears, a special test called the Schirmer tear test is done. A small strip is set in the eye, and in a duration of one minute, tears are allowed to soak the strip. This strip is then compared to normal values and results confirm the extent of the dog dry eye problem. Isolation and culturing of eye discharge can only confirm the presence of a infection, which are certain to be found with canine dry eye, thus possess no significance in confirming a cause. Testing does allow the status of the condition to be

Treatment of Dog Dry Eye:

Treatment of dry eye in dogs is done with specific antibiotics. Commonly, cyclosporine is preferred. These medications not only control the bacterial population, but also help in the flow of tears.

In a study, it has been proven that canine dry eye can be effectively treated if antibiotics and corticosteroids are administered in combination. Along with the use of a antibiotic-corticosteroid combination, dog eyes should be regularly washed and cleaned and kept moist with the help of isotonic solutions such as Opticlear.

Some natural remedies meant for eye health, such as Eye Heal can also help in this regard.

In severe conditions, surgery can help to treat any mechanical and/or anatomical deformity. On the other hand, an uncommon way of treating a irrecoverable dry eye condition is the transplantation of a salivary duct into the upper eyelid, enabling the flow of moisturizing fluid over the eye surface. This is a relatively uncommon way of treating dog dry eye, but may be practiced if needed.

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References:

Merck Veterinary Manual (Merck & Co.)

American College of Veterinary Opthamologists