I'm sorry to hear of this with Missy. Palladia is a drug approved for grades II or III canine mast cell tumors. It has become a standard of care drug for that use and has increased life expectancy. It's not a cure; it should be considered a chemotherapeutic agent and patients become refractory to the drug just as they do to other chemo drugs. I regret that I can't be more specific concerning Missy's prognosis if she's administered the drug versus not being administered it. I would need to know much more about her mast cell cancer. I can tell you the following:
When Palladia is used in the presence of systemic mast cell tumors, significant mast cell degranulation (the granules inside the mast cells rupture out of the cell) can occur with resultant adverse effects. Attempts to rule out systemic mastocytosis prior to starting Palladia should be performed.
Palladia isn't without its adverse effects. The most common adverse effects are diarrhea, decreased/losss of appetite, lameness, weight loss, and blood in the stool.
Adverse effects can be serious and require treatment pause or dose reduction.
Monitoring is essential.
Consultation with a veterinary oncologist should be considered.
Prednisone can be continued after Palladia treatment has begun but the two drugs shouldn't be given on the same day in order to avoid gastrointestinal distress as evidenced by inappetence, vomiting and/or diarrhea.
Please respond with further questions or concerns if you wish.