Masitinib mesylate

What is this medication for?

• Nonresectable grade II/III cutaneous mast cell tumors; atopic dermatitis (limited studies, moderate efficacy — mast-cell pathogenesis implication)
• Investigational only — poor tolerance

How is it given?

Give exactly as your veterinarian prescribed — never change the dose or stop on your own unless your veterinarian has told you to.

What if I miss a dose?

• Give it as soon as you remember — unless it is almost time for the next dose (then skip the missed one; never double up).
• Call your clinic if you miss more than one dose in a row.

Side effects — what should I watch for?

Effects listed as common in this handout

• stomach/intestinal disturbance (Main canine effect)
• Vomiting/diarrhea (prominent), protein in the urine, low infection-fighting cell counts (Cats particularly prone)

Worth a phone call to your veterinarian

• Reversible protein loss (protein-losing enteropathy/nephropathy pattern) (Documented — monitor proteins)

⚠️ Contact your veterinarian or an emergency clinic IMMEDIATELY if you notice

• Trouble breathing, collapse, seizures, severe vomiting or diarrhea, facial swelling, or pale gums

Before starting (or refilling), tell your veterinarian if your pet:

• has or has had: No formal contraindications reported; monitor albumin/urine protein periodically during therapy

• is pregnant, nursing, or used for breeding
• is taking any other medications, supplements, or flea/tick products, including:
  • None reported

Storage and handling

Tightly sealed, protected from light, room temperature/cool. 50/150 mg coated tablets, swallow whole.

Good to know

• The Kit-selective sibling of toceranib: same target family (Mast cell tumors), different selectivity profile and regulatory status (conditional approval in US as Kinavet-CA1 vs Palladia's full approval).
• The atopic-dermatitis signal (same 12.5 mg/kg dose) is pharmacology teaching a lesson: if masitinib helps atopic dogs, mast cells matter in atopy.
• Protein loss is the monitoring keystone (serum + urine) — the toxicity that defines patient retention.
• Not in Plumb's 7th ed. (2011) — this file is Papich 4th ed.-based, like telmisartan.