Dry Eye Syndrome

Dry Eye Syndrome, as its name suggests is a condition where not enough tears are produced. It is a painful condition that can lead to partial or total blindness. Also known as Keratoconjunctivitis Sicca or KCS, this condition is quite common in dogs and, although sometimes it can be a temporary reaction to some form of medical treatment or drug, most often it is actually a permanent condition which will require life long treatment.

The main known causes:

  • Bacterial Infections
  • Reaction to certain drug treatments
  • Removal of the lacrimal (tear secreting) gland of the third eyelid to treat “Cherry Eye”
    Note: This operation is not often performed anymore thanks to the development of better drug treatments in the form of eyedrops, but also because of the risk of the dog developing dry eye
  • Congenital disorders
    Note: certain breeds of dog have a predisposition to dry eye:
    Cocker Spaniels, Bulldogs, White Westies (West Highland Terriers), Lhasa Apsos, and Shih-Tzus
  • Diabetes
  • Hypothyroidism (underactive thyroid gland)

Symptoms:

  • Sticky mucus build up in and around the eye
  • Cloudy Eyes
  • Redness of the eye
  • Ulcers on the Cornea (the transparent, dome-shaped layer that covers the Iris and the Pupil)
  • After a while, the surface of the eye will develop a brown pigmentation which gradually spreads over the eye. This will impair the dog’s vision and can eventually lead to blindness.

Diagnosis:

The Schirmer Tear Test can be used to measure the amount of tears your dog’s eye is producing. This involves putting a special strip of litmus paper, which is marked with a measuring scale, under the bottom eyelid and leaving it there for 60 seconds. The tears are absorbed by the paper and the line the tears reach on the measuring scale indicates whether or not your dog is producing enough tears. A normal reading would be at least 15mm in one minute.

Treatment:

Treatment of Dry Eye depends on whether the tear gland is still functioning at all. In cases where the gland is still functioning, drugs that stimulate the production of tears can be used. If the gland is non-functional then management of the condition is all that can be achieved.In either case, treatment is usually in the form of eyedrops or ointment applied directly to the eye.
Note: Before applying the treatment, the eye must be gently, but thoroughly cleaned, removing any fresh or crusty build up of discharge in and around the eye.

  1. Drug Treatment:
      • Treatment for dogs with still functional tear glands:
        There are a range of drugs available known as lacrostimulants (lacro meaning tears). These stimulate the production of tears and can, in some cases reverse the damage to the tear gland and restart production of tears. Cyclosporin is one of the most popular lacrostimulant drugs  and usually comes in the form of an ointment applied to the eye.
        Note: Lacrostimulant drugs can take a while to work and so the dry eye will need to be managed whilst waiting for the drug to take effect. This will involve application of artificial tears and, if necessary, antibiotic treatment to clear any infection that may be present.

     

    • Treatment for dogs with non-functional or irreversibly damaged tear glands:
      Natural tear production will not be able to be stimulated and therefore the condition will need to be managed for the rest of the dog’s life. This is achieved with the application of artificial tears in the form of drops or ointments several times a day to keep the eye moist and to reduce irritation.
  2. Surgical Treatment:

    Surgical treatment is usually only used as a last resort:

    • Permanent Partial Tarsorrhaphy:
      This involves sewing together parts of the upper and lower eyelid to reduce the size of the eye exposed to the environment and therefore conserving the tears that are being produced.

     

    • Parotid Duct Transposition:
      This is the re-routing of the saliva (parotid) duct into the dog’s eye, therefore allowing saliva to act as a substitute for tears. The difficulty with this procedure is that too much fluid can flood the eye and the dog’s normal draining system won’t be able to cope, thus leading to a watery eye. Also the chemicals in saliva can irritate the eye.

Prognosis (Long Term Outcome of Treatment):

In some cases dry eye can be cured, but in many cases it is a condition that will remain for the rest of the dog’s life and must be managed with eyedrops, ointment and good hygiene. If caught relatively quickly the damage to the dog’s eyesight may be avoided or certainly minimised, but this also depends on the owner maintaining the treatment regime over the rest of the dog’s life.

Note: If not properly controlled dry eye can lead to partial loss of vision or even blindness but it is not, in itself a life threatening condition.


Further information:

For more detailed information on this condition the following websites are well worth a visit:

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