KCS is an eye disease which is one of the  consequences of lack of  producing enough tear.There are two source of tears,a lacrimal gland on the lateral canthus of eye and the second is another gland which is situated in the third eyelid on the medial canthus of eye.These two glands produce tear to wash the cornea to moisturize it.Lack or deficiency  of tear  causes dry cornea ( dry eye).Dry eye is prone for infection and corneal ulcer.

 Reasons of dry eye:

The involved factors can be classified in

1-Congenital defect of lacrimal glands

2- Senility: in old age lacrimal atrophy affects its function

3-Trauma to eye and  around it can affect lacrimal glands or the nerves which support these glands.

4-Immune mediated disease

5-Medications like non-steroidal antiinflammatory drug or sulfonamides

6-Surgery:  removal of the third eyelid during surgery

 Clinical signs:

1-It  starts with red eye and then  mucopurulent discharge is the most consistent clinical sign.

2-Corneal ulcers

3-Tight closure of the eyelids and difficult to open eye ( blepharospasm)

4-Chronic eye infection

 Diagnosis:

Taking history, clinical signs and measuring tear production and fluorescein or rose bengal staining test can lead to diagnosis.

 Treatment:

veterinarians on the basis of their diagnosis introduce the choice of therapy to the clients

1-Medical therapy includes stimulation of tear gland to produce tear  or using artificial tear every day

2-Surgical procedure: in this surgery, surgeon makes a connection between parotid gland  and conjunctival sac to moisturize cornea by saliva