Welcome to Justanswer! I am Dr. Altman and happy to assist you both today!
I am sorry to hear Jameson is not feeling well today. Although it is unlikely it is related to the mast cell tumor there is a possibility if the margins of removal were not clear or an ultrasound was not performed to ensure no metastasis was found. I can give you some basic guidelines to hopefully get him feeling better but if he is still vomiting by tomorrow then please consider having your vet evaluate him and give stronger medications to control his symptoms and determine the underlying cause.
1- Keep indoors to avoid eating grass/ leaves for 6-8 hours from last vomiting episode
2- Offer a small amount of water (1-2 teaspoons hourly) for a few hours after the 6-8 hours to test the stomach. Even if he is holding down water now to test whether administering pepcid is safe
3- Start Pepcid (famotidine) 0.25 mg/ pound every 12 hours OR prilosec (omeprazole) 0.5 mg/ pound daily for the next 3 days with the second administration of water (crushed if needed)
4-If no vomiting, offer small amount of white rice and boiled boneless or ground chicken or ground beef. For example, one tablespoon hourly for a few hours then slowly start to increase the amount while reducing the frequency. Keep on this diet for several days then wean into regular diet.
5- If vomiting continues after doing the above, I would encourage having your family veterinarian perform an examination to determine the next step to getting Jameson comfortable and what exactly the underlying cause is.
Indications your dog should be seen by a veterinary er sooner include: sticky gums that are pale, yellow, blue, purple, temperature rectally >103.5, progressive lethargy with less responsiveness to you, vomiting or diarrhea that includes blood, resting respiratory rate (breaths per minute) >60, swollen abdomen.
Please let me know if I can be of any further assistance to you both today
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