Effects of different mydriatics on intraocular pressure, pupil diameter, and ruminal and intestinal motility in healthy sheep.
OBJECTIVE
To determine the effects of the administration of subconjunctival 1% atropine (SA), topical 1% atropine (A), 0.5% tropicamide (T), 1% homatropine (H), 10% phenylephrine (P), and 2% ibopamine (I) on intraocular pressure (IOP), pupil diameter (PD), ruminal motility (RM) and intestinal motility (IM) in sheep.


METHODS
Ten spayed ewes of Santa Inês breed.


METHODS
Six experiments were performed separately at 1-week intervals. One eye was randomly selected and received one drop of A, T, H, P, I, or subconjunctival injection of atropine at 8 a.m. On the following days, IOP and PD were evaluated every 8 h until the pupil returned to its normal diameter. Ruminal motility and intestinal motility were evaluated only within the first 13 h.


RESULTS
The IOP did not change significantly in the treated eyes compared with the control eyes and baseline at any time point (P > 0.05). A longer-lasting pupil dilation was observed after the administration of A (96 h), SA (79 h), H (24 h), and T (24 h). Within the first 30 min after treatment, RM and IM decreased, by 78% and 82% (H), 76% and 86% (SA), 46% and 58% (A), and 62% and 70% (T) (P < 0.001), respectively, with a tendency to return to baseline values following 13 h of drug administration. Both 10% phenylephrine and 2% ibopamine did not have any effect on the parameters evaluated (P > 0.05).


CONCLUSIONS
Topical and subconjunctival 1% atropine, 0.5% tropicamide, and 1% homatropine significantly reduced RM and IM, and induced pupil dilation but did not change IOP in eyes of healthy sheep. The sympathomimetics phenylephrine (10%) and ibopamine (2%) did not change the parameters evaluated.
College of Agronomy and Veterinary Medicine, Federal University of Mato Grosso, Av. Fernando Corra da Costa, n° 2367 Bairro Boa Esperança, 78060-900, Cuiab, MT, Brazil.
Alexandre P
AP
Ribeiro
Roberta M
RM
Crivelaro
Pedro Paulo M
PP
Teixeira
Dunia Y
DY
Trujillo
Patrícia J
PJ
Guimarães
Wilter Ricardo R
WR
Vicente
Bianca da C
Bda C
Martins
José Luiz
JL
Laus
D000818:Animals; D004333:Drug Administration Routes; D005260:Female; D005769:Gastrointestinal Motility / Q000187:drug effects*; D007429:Intraocular Pressure / Q000187:drug effects*; D009184:Mydriatics / Q000008:administration & dosage / Q000494:pharmacology*; D011680:Pupil / Q000187:drug effects*; D012417:Rumen / Q000187:drug effects* / Q000502:physiology; D012756:Sheep / Q000502:physiology*
D009184:Mydriatics
atropine; parasympatholytics; phenylephrine; sheep; sympathomimetics; tropicamide