Maropitant prevented vomiting but not gastroesophageal reflux in anesthetized dogs premedicated with acepromazine-hydromorphone.

OBJECTIVE: To evaluate the efficacy of maropitant for prevention of vomiting and gastroesophageal reflux (GER) in dogs following acepromazine-hydromorphone premedication and inhalation anesthesia. STUDY
DESIGN: Randomized, blinded, prospective clinical study. ANIMALS: Twenty-six dogs admitted for elective soft tissue or orthopedic procedures that were 3.1 ±3.1 years of age and weighed 20.5 ± 11.4 kg.
METHODS: Dogs were randomly assigned to one of two groups: Group M received maropitant (1.0 mg kg(-1) ) and Group S received 0.9% saline (0.1 mL kg(-1) ) intravenously 45-60 minutes before premedication with hydromorphone (0.1 mg kg(-1) ) and acepromazine (0.03 mg kg(-1) ) intramuscularly. An observer blinded to treatment documented any retching or vomiting for 20 minutes before induction with propofol (2-6 mg kg(-1) ) and inhalation anesthesia. A pH probe inserted into the distal esophagus was used to detect GER.
RESULTS: None of the dogs in Group M retched or vomited (0/13), 6/13 (46%) in Group S were observed to retch or vomit, and the difference between groups was significant (p = 0.015). There were no differences between groups in the number of dogs with GER (Group M: 4/13, Group S: 6/13 dogs) or the number of reflux events. Esophageal pH at the end of anesthesia was significantly lower in both M and S groups in dogs with GER versus dogs without GER (p = 0.004 and 0.011, respectively). Only dogs with GER in Group S had significantly lower pH at the end compared to the beginning of anesthesia (p = 0.004). CONCLUSIONS AND CLINICAL RELEVANCE: Intravenous maropitant prevented retching and vomiting associated with acepromazine-hydromorphone premedication. Maropitant did not prevent the occurrence of GER. Fewer dogs in Group M developed GER but further study with a larger number of dogs is necessary to determine if there is a significant difference.