Effect of single-dose intravenous furosemide on basal tear secretion in healthy dogs

This study investigated the effect of intravenous furosemide on basal tear secretion in healthy dogs. Six healthy beagle dogs (three males and three females) aged 1.5–2.8 years were enrolled in this randomized, cross-over, blinded study. All dogs were administered one of three medication protocols in a randomized, cross-over manner: high-dose (HD) furosemide (furosemide 4 mg/kg IV), low-dose (LD) furosemide (furosemide 2 mg/kg IV), or placebo (saline 0.3 mL/kg IV). The Schirmer Tear Test II for dogs was performed to measure basal tear secretion before and 30, 60, 90, and 120 min after the administration of furosemide or saline. Blood samples were collected for total protein (TP) and packed cell volume (PCV) measurements before and 120 min after medication or placebo administration. Basal tear secretion significantly increased in the LD and HD groups compared with that in the placebo group. Significant differences were identified in TP and PCV between the HD and LD, between the HD and placebo groups, and between the LD and placebo groups. In healthy dogs, a significant increase in basal tear secretion was observed in the LD and HD groups compared with that in the placebo group.