Effectiveness of dimenhydrinate and maropitant in preventing preoperative emesis and nausea in healthy dogs sedated with hydromorphone and dexmedetomidine: a randomized, blinded trial.

OBJECTIVE

To determine the antinausea and antiemetic effects of dimenhydrinate and maropitant in dogs when administered 60 minutes before hydromorphone and dexmedetomidine.

STUDY

DESIGN

Prospective, randomized, blinded, placebo-controlled clinical trial.

ANIMALS: A total of 87 healthy client-owned dogs undergoing ovariectomy/castration.

METHODS

Dogs were randomly assigned to be administered maropitant (1 mg kg-1; group M) subcutaneously (SC), dimenhydrinate (4 mg kg-1; group D) intramuscularly (IM), or 0.9% NaCl (0.1 mL kg-1; group C) SC 60 minutes before anesthetic premedication with hydromorphone (0.1 mg kg-1) and dexmedetomidine (5-15 μg kg-1) IM. Incidences of discomfort after injection of the treatment drug, nausea (ptyalism, lip licking, and swallowing), and vomiting/retching were documented. Scores for nausea and sedation were assigned immediately before premedication and for 20 minutes after premedication. Data were analyzed using Fisher's Exact test and Kruskal-Wallis test, with statistical significance set at p< 0.05.

RESULTS

Discomfort to injection was significantly higher in group M (20/31, 64.5%) than in groups D (6/28, 21.4%) and C (2/28, 7.1%) (p< 0.0001). Incidence of nausea was not significantly different between treatment groups [group M; 23/31 (74.2%) versus group D; 27/28 (96%) versus group C; 23/28 (82.1%), p= 0.050]. The incidence of vomiting/retching was significantly lower in group M (0/31, 0%) compared to groups D (15/28, 53.6%) and C (9/28, 32.1%) (p< 0.0001).

CONCLUSIONS AND CLINICAL RELEVANCE: Dimenhydrinate produced no measurable antinausea and antiemetic effect when administered 60 minutes before hydromorphone and dexmedetomidine. Maropitant SC prevented hydromorphone-induced emesis but was ineffective in reducing nausea.