An antiemetic drug is one that stops or lessens the symptoms of nausea and vomiting. The acids associated with vomiting can burn a dog's sensitive esophagus. Antiemetic drugs are prescribed when a cause for illness has been determined, to prevent motion sickness, alleviate the side effects of chemotherapy, and to help with psychogenic vomiting.
Phenothiazine drugs, a class that includes Thorazine, work on the emetic center of the dog's brain to control vomiting. Mild sedation is a side effect.
Metoclopramide, sometimes known as Reglan, is often a second choice in antiemetic drugs. While it also works on the emetic center of the brain, it also facilitates the emptying of the intestines without increased acid secretions.
Phenothiazine and Metoclopramide
The two drugs might be used in conjunction with one another if neither are effective by themselves, or if the dog seems particularly anxious or depressed.
Ondansetron, known under the brand name Zofran, has proven to be an effective antiemetic for dogs undergoing chemotherapy. It blocks certain serotonin inhibitors in the brain that might lead to vomiting. It is not effective in treating motion sickness.
In a controlled study conducted by Tufts University, Butorphanol was found to be 81 percent effective at controlling the vomiting of dogs that were undergoing cisplatin-based chemotherapy.