About stelfonta treatment for Mast Cell Tumor on Dogs
Your dog has been diagnosed with a Mast Cell Tumor, and your veterinarian has prescribed STELFONTA. On this page, you will find information about the treatment process, pretreatment preparation and how to care for your dog afterward. Remember, always speak with your veterinarian if you have any questions about your dog’s treatment.
Stelfonta how it works

Things to keep in mind:

  • Your dog must be administered Prednisone, Benedryl and Pepcid at least 2 days before the procedure.
  • Your dog must be administered Prednisone, Benedryl and Pepcid for at least 10 days after the procedure.  Failure to give these medications as directed can lead to severe complications and even death. 
  • We expect a wound to form
  • Antibiotics are not needed (Stelfonta aids in the healing of healthy tissue)
  • Bandages are not needed
  • E-collars are not needed.  In fact, dogs are allowed to lick these areas. 
  • If you find yourself at an ER, or visit another veterinarian, please be VERY clear to your veterinarian that your pet is going through Stelfonta treatment.  Not all veterinarians are familiar with Stelfonta.  They may be concerned by the wound.  It does not need to be closed, it does not need to be bandaged, antibiotics are not needed.  This is the expected healing process for Stelfonta. 

What to expect after treatment:

Within 2 hours of treatment, bruising, heat, pain, and swelling may begin at the site and may last up to 4 days or more days. During this time, pain meds may be needed in addition to the use of steroids and both benedryl and pepcid. It is essential dogs receive all 3 medications as directed.

Report of excessive pain, lameness, tiredness, refusal to eat for more than one day, repeated vomiting or diarrhea, trouble breathing, changes to the treated tumor site (including increased or excessive swelling and bruising, extensive wound formation, increased irritation) or any other symptoms should be examined immediately and treated accordingly.

By Day 4, some dogs may exhibit intact skin while others may be observed with necrosis, discharge, or ulceration without excessive pain, excessive swelling and bruising, extensive wound formation or other clinical signs. If excessive pain, increased or excessive swelling and bruising, extensive wound formation or other clinical signs are observed, the dog should be examined.

By day 7 after treatment, wound formation including full thickness dermal necrosis with discharge, peripheral tissue edema, redness, skin discoloration, tissue sloughing, and necrosis may occur. Discharge may be clear, red, or cloudy.

Sloughing of the treated site was observed from Day 7 to Day 42, with decreasing frequency after Day 7.

By Day 28, 75% of dogs experienced a complete response.

By Day 84, 96% of dogs were disease free.

The wound resulting from the administration of Stelfonta may be larger than expected.  It is possible this is due to microscopic extension of the tumor through the tissue.  In these cases, healing still occurs as expected, without additional surgery, bandaging or antibiotics.

Stelafonta Example1
stelfonta tips


Contact your veterinarian right away if:

  • Excessive pain or limping
  • Tiredness or refusing to eat for more than one day
  • Repeated vomiting or diarrhea
  • Trouble breathing
  • Excessive swelling, bruising, irritation or wound formation at the treatment site
  • Any other symptoms your dog may show that concern you
stelfonta treatment success
Stelafonta Example2
Stelafonta Example3
Stelafonta Example4