Em. Smith et al., EFFECT OF TOPICAL PILOCARPINE TREATMENT ON TEAR PRODUCTION IN DOGS, Journal of the American Veterinary Medical Association, 205(9), 1994, pp. 1286-1289
Tear production, evaluated every 2 hours from 8 AM to 8 PM by use of t
he Schirmer tear test over a 3-day period, was not significantly diffe
rent between left and right eyes in 12 dogs. However, a significant di
urnal pattern was evident. Tear production was lowest at midday and hi
ghest in the late afternoon/early evening. After pilocarpine HCl ophth
almic solution (0.25, 1.0, or 2.0%; 1 drop) was administered topically
to the left eye of each dog at 7 AM on days 4, 6, and 8, respectively
, tear production war determined for both eyes every 2 hours from 8 AM
to 8 PM on the day of treatment. Analysis of tear values between eyes
and between each eye's treatment and pretreatment values did not reve
al significant change for the treated eye, but tear production was sig
nificantly less in the untreated eye, compared with its pretreatment v
alues and with values in the treated eye. On day 10 (48 hours after th
e last treatment), tear production values were not significantly diffe
rent between left and right eyes, and for both eyes, were not signific
antly different from the mean pretreatment tear production values. Top
ical application of 0.25, 1.0, or 2.0% pilocarpine HCl consistently ca
used blepharospasm, conjunctival hyperemia, and miosis of the treated
eye, without significant increase in tear production. We concluded tha
t topical application of pilocarpine, at the concentrations used, may
have little value in treating disorders involving reduced tear product
ion.