This report has two parts. Part one evaluated two types of medical silicone lacrimal punctal plugs with shaft diameters of 0.4 to 0.8 mm in 100 dogs of different breeds and size. Punctal plug size was directly related to dog size, and plugs with shaft diameters 0.6 to 0.8 mm were most useful. Dogs weighing more than 30 kg had lacrimal puncta larger than 0.8 mm, and plugs for dogs of this size fit loosely. In the second part, an additional 10 dogs with keratoconjunctivitis sicca received punctal plugs to the lower lacrimal ducts to conserve available tears. Schirmer tear test levels increased from 2.3 ± 1.7 to 3.8 ± 2.7 mm wetting/min. Fourteen of the eyes in eight dogs demonstrated clinical improvement; in three dogs, punctal plugs reduced the frequency of artificial tear replacement therapy.

COMMENTARY: Punctal plugs may be useful to treat dogs with keratoconjunctivitis sicca but some tear production (2 to 3 mm wetting/min by Schirmer tear test) must be present.

Use of punctal occlusion in the treatment of canine keratoconjunctivitis sicca. Williams DL. J Small Anim Pract 43:478-481, 2002