Ondansetron for Nausea in Vestibular Disease

Vestibular disease, whether it is central or peripheral in origin, can result in nausea and vomiting. The exact mechanism is unclear, but it is suspected to be via neuronal projections to higher centers (forebrain) and associated with activation of 5-HT3 receptors. Ondansetron is a selective 5-HT3 receptor antagonist (blocker). It has been shown to be effective on subjective observation, in controlling nausea in vestibular patients, but a recent double-blind placebo controlled study took it one step further. In addition to observation of signs of nausea, such as lip licking, facial expression, behavioral clues and hypersalivation, they evaluated blood levels of arginine vasopression (AVP) which has been positively correlated with nausea scores. 

Materials and Methods

Eighteen dogs were enrolled, 14 were included in data analysis. Six dogs received placebo first, followed 2 hours later by ondansetron (0.5 mg/kg IV, diluted 1:1 with 0.9% saline). Eight dogs received ondansetron first, followed 2 hours later by placebo. Dogs were observed at hourly time points for signs of nausea (pre and post treatment) and had serum samples for AVP measurements taken at pre-treatment, 2 and 4 hours post initial treatment. 


Key Results

  • Dogs given ondansetron, showed a rapid, significant reduction in nausea compared to dogs given placebo. 

  • Only 4 dogs vomited, in addition to signs of nausea. ** Vomiting should not be the only sign you watch for to say a pet needs an anti-nausea medication!

  • Serum AVP concentrations decreased significantly after administration of ondansetron, compared to placebo. 


Based on the data presented, it is reasonable to assume any dog with recent onset vestibular signs should be administered ondansetron if signs of nausea and/or vomiting are noted. It would be helpful to educate clients on the signs of nausea (not just refusing food or vomiting!) when performing at-home observation of their pets with vestibular disease.

Interested in learning more about the nausea scores? Please consider this reference:
1. Kenward H. Development of an objective means of assessing nausea in dogs. London:EThOS British Library; 2015. 


I hope you're doing well and look forward to working with you soon! 

 Reference for article discussed above: 0.1111/jvim.16504