title: Topical application of 0.005% latanoprost increases episcleral venous pressure in normal dogs.
abstract: BACKGROUND
  Episcleral venous pressure (EVP) has an important role in intraocular pressure (IOP) homeostasis and accounts for more than 70% of the IOP in the normal dog. A frequently used species in glaucoma research is the normotensive dog especially when evaluating the efficacy of prostaglandin analogues and prostamides; however, aqueous humor dynamic studies in normal dogs are lacking, and the effect of 0.005% latanoprost on canine EVP is not known. We sought to determine the effects to the EVP of topically applied 0.005% latanoprost in the normotensive beagle dog.
  
  
  METHODS
  Female beagle dogs (n = 14) were used and each had a normal ophthalmic examination on study entry. EVP was determined using a standard episcleral venomanometer. Animals were dosed in one eye with 0.005% latanoprost, and the effects on EVP were compared with the averaged baseline EVP's determined in the predosing phase and the fellow nondosed eye. The Mixed Model Repeated Measures method was used to analyze the EVP data.
  
  
  RESULTS
  During the dosing phase of the study with topical 0.005% latanoprost, the mean EVPs of dosed eyes were significantly higher than that of nondosed eyes (P < 0.0001).
  
  
  CONCLUSIONS
  The increase in EVP in the dog with exposure to topical 0.005% latanoprost has not been observed in other species that have been studied, such as in the mouse and in humans, where the drug had no significant effect on the EVP. This response may be unique to dogs and suggests that dogs may not fully mimic human aqueous humor dynamics with topical 0.005% latanoprost. Although frequently performed in human studies, EVP should not be regarded to be a constant value in aqueous humor dynamic studies in the normal beagle dog.
authors: College of Veterinary Medicine, Colorado State University, 4408 John F Kennedy Parkway, Apt C202, Fort Collins, CO 80525, USA. sytsai@rams.colostate.edu
authors: Susan
authors: S
authors: Tsai
authors: Paul E
authors: PE
authors: Miller
authors: Craig
authors: C
authors: Struble
authors: Susan
authors: S
authors: Howard
authors: Alexandra
authors: A
authors: Almazan
authors: James A
authors: JA
authors: Burke
authors: Patrick M
authors: PM
authors: Hughes
authors: Huajiang
authors: H
authors: Li
authors: Paul
authors: P
authors: Conforti
authors: Susan S
authors: SS
authors: Lee
authors: Michael R
authors: MR
authors: Robinson
mesh_terms: D000287:Administration, Topical; D000818:Animals; D000959:Antihypertensive Agents / Q000008:administration & dosage / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects*; D004285:Dogs; D005260:Female; D000077338:Latanoprost; D011461:Prostaglandins F, Synthetic / Q000008:administration & dosage* / Q000494:pharmacology*; D012590:Sclera / Q000098:blood supply* / Q000187:drug effects
chemical_list: D000959:Antihypertensive Agents; D011461:Prostaglandins F, Synthetic; D000077338:Latanoprost