Maropitant Citrate Administration Significantly Decreases the Rate of Peristalsis in the Stomach and Jejunum and Does Not Significantly Alter Intestinal Diameter or Intestinal Wall Thickness in Healthy Adult Dogs.

Maropitant citrate (Cerenia) is a neurokinin-1 (NK-1) receptor antagonist labeled for the treatment of vomiting in dogs and cats. Anecdotal observation at the authors' institution suggests that patients receiving maropitant citrate occasionally display sonographic and radiographic signs of diffuse functional ileus. The goals of this prospective one-group pretest, posttest study were to determine if administration of maropitant citrate caused changes in ultrasonographic wall thickness and peristaltic rate at the pylorus, duodenum, or jejunum and/or a radiographic change in intestinal diameter or appearance. Twenty-one healthy adult dogs (ages 1-8 years) were recruited. After overnight fasting, abdominal radiographs and a brief gastrointestinal ultrasound were performed at time 0 (baseline), followed by a 1 mg/kg subcutaneous dose of maropitant citrate. Imaging was then repeated 1 and 3 h post maropitant administration. Peristatic contractions and wall thickness at the pylorus, duodenum, and jejunum were measured with ultrasound, and radiographs were assessed for signs of functional ileus (mild diffuse dilation of the small intestine or mild increase in overall small intestinal gas content). Significant decrease in rate of peristalsis of the pylorus (p < 0.001, hp