The medical term for Dry Eye is Keratoconjunctivitis sicca, usually abbreviated to KCS and is where insufficient tears are produced leaving the eye drier than is usual. It is also seen in cats, but is more common in dogs. Imagine getting grit in your eye & not having tears to help wash it away. Tears are not just water, but are actually quite complex in structure, and serve several functions. They lubricate and flush the eye, provide nutrition and oxygen to the cornea, and also have a role in preventing bacterial infections of the eye.
Any dogs can be affected, but these breeds are generally more susceptible to it – Collies, Labradors, Bulldogs, Yorkies, Jack Russells, Westies, Lhasa Apso, Shi Tzu, Cocker & KKC Spaniels. We particularly see the problem in Westies.
Conjunctivitis & inflammation of the inner eyelids are the earliest symptoms. Although conjunctivitis tends to respond to antibiotic drips, the Dry Eye will usually reappear after that course of treatment ends. Mucous threads can appear on the surface of the eye or build up around the lower eyelid.
If left untreated the condition can lead inflammation of the cornea or front of the eye. At this point the eye will lose its shine and anything reflected in the eye will appear indistinct. The dog may feel discomfort & rub the eye with corneal ulcers often appearing. Over time, the cornea becomes scarred and pigmented and eventually lead to reduced vision or blindness – both of which are irreversible.
The commonest cause is a fault of the dogs immune system where it identifies the dogs own tear glands as foreign, and attempts to destroy them. This results in tear production being reduced or lost altogether.
Some dogs are born with defective tear glands. Viral infections such as Canine Distemper or Feline Herpesvirus can lead to Dry Eye or a hormone imbalance from an underactive thyroid gland.
There is a specific test for Dry Eye called the ‘Schirmer Tear Test’ and involves placing a strip of paper between the lower eyelid and the eyeball for 1 minute and seeing how far a tear travels. Movement of more than 15mm is normal and under 10mm is abnormal.
There is currently no cure for Dry Eye, but it is a condition that can be effectively managed with medication or through the use of artificial tears used to wet the eye.
The medication used is Cyclosporine which is available in an ointment called Optimune. The ointment is usually applied twice daily & acts to prevent the immune system from destroying the tear glands. Where the condition is in an advanced stage & the tear glands have already been destroyed, this treatment is ineffective. In less severe cases though, a one month course of treatment is usually sufficient to increase tear production.
Artificial tears are slightly viscous drops that wet the eye and have to be applied at least once every two hours to be effective. Although cheaper, they require much greater involvement of the owner, which is not always possible with people’s busy schedules.
Surgical treatment can also be undertaken where the output of the salivary glands is moved to the eye. This surgery requires a specialist eye surgeon, is expensive and also has its own problems. As a result it is usually only ever a last resort after other treatment options have failed.
The outlook for the dog is dependant on the underlying cause and how long the dog has been affected. It is therefore important that owners check their dogs eyes on a regular basis and get them checked by a vet if they notice any mucus threads or apparent signs of conjunctivitis.