CHAPTER III. 

 DISEASES OF THE LACRIMAL APPARATUS. 



Examination.— This apparatus consists of the lacrimal 

 gland and the lacrimal passages. In small animals it is 

 somewhat difficult to make an examination of the entire 

 apparatus. The lacrimal gland in the dog is flat, light pink 

 in color, of a mixed type and is situated in the periorbit 

 directly under the orbital ligament. In the cat the position 

 is very similar. In birds the gland is a small, round, reddish 

 body against the eyeball near the outer canthus and opens 

 upon the wall of the eyelid through a small slit. 



The lacrimal openings (puncta lacrimalia) are elliptical 

 fissures and are two in number in the dog and one in the bird. 

 The lacrimal canal extends from the lacrimal gland to an 

 opening in the lower border of the nasal canal. This is a 

 whitish, membranous tube to conduct the excessive secretion 

 into the nasal passages. The entire lacrimal apparatus is of 

 lesser importance in small animals than in horses. 



LACRIMATION. 



Epiphora. 



Definition.— A term applied to designate a flow of tears 

 over the lid margins. It is not of common occurrence in 

 small animals, except in certain breeds of dogs. 



Etiology.— (a) Very often due to ectropion or entropion, 

 which may produce a deviation of the puncta lacrimalia, 

 allowing the secretion to flow out over the margin of the lids. 

 (6) Obstruction of the lacrimal duct by foreign substances, 

 mucus, etc. (c) Constriction and obliteration of the duct 

 due to injuries, etc. (d) Lacrimation is often seen as a result 

 of irritation or diseases affecting the conjunctival membranes. 

 In this case the secretion forms so rapidly that the lacrimal 

 duct cannot carry it away, the excess flowing over the lid 

 margins, (e) Ordinary lacrimation may be produced by 

 exposure to irritating gases, smoke, dust or cold air. 



