title: Effect of short-term diphenhydramine administration on aqueous tear production in normal dogs.
abstract: OBJECTIVE
  To perform a randomized, placebo-controlled, masked clinical trial using a cross-over design to determine the effect of oral diphenhydramine on aqueous tear production in normal dogs.
  
  
  METHODS
  Seventeen dogs with normal ophthalmic examinations.
  
  
  METHODS
  Baseline tear production was established for each dog by performing Schirmer tear test I (STT I). Dogs received 20-day treatment courses of both oral diphenhydramine and placebo solutions with a 10-day washout period between treatment periods. Each dog was randomly assigned to receive diphenhydramine or placebo at the outset of the study. Measurements of STT I values were measured at regular intervals during the study and were conducted at the same time of day throughout the study to control for diurnal variations in tear production. The significance of the impact of diphenhydramine treatment on the quantity of aqueous tear production, as determine by STT results over time, was evaluated using regression analysis with appropriate transformation.
  
  
  RESULTS
  Statistical comparisons at each measurement time, including baseline measurements between control and treatment groups, revealed no significant differences. Mean STT I levels also did not differ significantly at any measurement time compared to baseline for treatment or control groups.
  
  
  CONCLUSIONS
  Short-term administration of oral diphenhydramine does not result in a significant decrease in aqueous tear production in normal dogs.
authors: Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA. kmontgomery@fvarc.com
authors: Keith W
authors: KW
authors: Montgomery
authors: Eric C
authors: EC
authors: Ledbetter
authors: Hussni O
authors: HO
authors: Mohammed
mesh_terms: D000284:Administration, Oral; D000818:Animals; D004155:Diphenhydramine / Q000008:administration & dosage / Q000494:pharmacology*; D004285:Dogs; D005260:Female; D006634:Histamine H1 Antagonists / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D013666:Tears / Q000187:drug effects* / Q000378:metabolism
chemical_list: D006634:Histamine H1 Antagonists; D004155:Diphenhydramine