Your dog is drooling, lip-smacking, and turning away from the bowl. If you have reached for the Zofran in your own medicine cabinet, put it back. Zofran (generic name ondansetron) is a human prescription drug, and while vets do use it in dogs, the dose has to come from them.
Ondansetron blocks the serotonin receptors in the brain and gut that trigger nausea, and it usually starts working in 30 to 60 minutes. It comes as tablets, liquid, dissolving tablets, or an injectable form used in clinics. Whole Dog Journal’s guide to Zofran for dogs adds a practical note: with a dissolving tablet, wear dry medical gloves, since the drug absorbs through skin.
Vets reach for it when nausea has a known cause, usually alongside another drug such as maropitant (Cerenia). That guide’s author described her own dog, in lymphoma treatment, drooling through one anti-nausea medication and settling once ondansetron was added.
Here is what this means for your dog. Never dose from your own bottle: one naproxen tablet can cause kidney failure in a dog. The amount depends on your dog’s weight and health, and it interacts with tramadol, cyclophosphamide, some antidepressants, and some heart medications. Doses usually run twice a day, and a missed one is a call to your vet, not a double dose later. Watch for drowsiness, diarrhea, or restlessness, and treat facial swelling or trouble breathing as an emergency.
Drooling plus lip licking plus refusing food is nausea, not the ordinary stomach gurgling that follows a weird snack. Ondansetron quiets the nausea without touching what is causing it, so a settled stomach is not an all-clear. Call your vet if vomiting lasts past a day, if you see blood, or if your dog cannot hold water down.