Tigilanol tiglate, derived from the fruit of the tropical blushwood tree in Australia, may be the most exciting news the dog world has received in the last decade. Tigilanol tiglate is the active substance in Stelfonta, now approved for veterinary use in Europe and by the F.D.A.’s Center for Veterinary Medicine in the U.S. This cancer veterinary medicine has shown highly promising results in Mast Cell Tumor (MCT) treatment in dogs for MCT’s in the skin or the tissues just under the skin. Following studies in 2014, Chad Johannes, D.V.M., DACVIM (SAIM, Oncology), one of the study authors, said, “To have such a high response rate for a cancer drug is not common.”

What are Mast Cell Tumors?

Mast Cell tumors (MCT) are the cancer of a type of blood cell, and they are the most common malignant skin tumor in dogs. However, they can also affect other areas in the body. As much as 20% of skin masses in dogs could be MCTs. They can range in severity from the very low-grade tumors to the more ominous higher-grade tumors that are more likely to spread or metastasize. While treatments such as chemotherapy, radiation, and surgery exist, they are not always appropriate for every dog.

Symptoms of Mast Cell Tumors

Sometimes the only symptom may be a mass or lump, while in other cases, the mast cells may cause other symptoms if they release histamine. This release can lead to vomiting, diarrhea, skin redness, swelling, or loss of appetite.

If cancer has reached an advanced stage and has already spread to other organs, then dogs with mast cell tumors may also suffer from internal bleeding or fluid accumulation.

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Stelfonta adds another option in the fight against MCT’s.

Stelfonta has received F.D.A. approval to treat non-metastatic skin-based (cutaneous) mast cell tumors in dogs. That is, treatment for tumors when cancer has not spread from the primary site. Additionally, tumors must be less than or equal to in volume, and accessible to intratumoral injection.


Tigilanol tiglate stimulates the action of protein kinase C enzymes. When these enzymes are activated, they interrupt the blood supply to cells, resulting in those cells’ death. Additionally, the drug also activates the body’s immune system to promote wound healing. The medicine is most helpful Mast Cell Tumor treatment in dogs for MCT’s that are not suitable for surgery, and that has not yet spread to other parts of the body.

“This is the first approval for an intratumoral injection to treat non-metastatic mast cell tumors in dogs,” said Steven M. Solomon, D.V.M., M.P.H., director of the F.D.A.’s Center for Veterinary Medicine. “This approval provides an additional treatment option to help treat local mast cell tumors on or under the skin in dogs.”

Virbac, a global animal health company that has launched the Stelfonta product, has stated the following:

  • 75% of mast cell tumors achieved resolution of the target tumor with just one treatment
  • 88% of dogs achieve the target tumor’s resolution 28 days after either the first or 28 days after a second treatment.
  • 12 weeks after a single injection, 96% of dogs remained disease-free at the site of the treated tumor
  • In 98.2% of cases, complete healing was observed within three months
  • Most wounds were re-epithelialized entirely within 28 to 42 days of treatment, with good cosmetic outcomes
  • The treatment is generally well-tolerated and does not adversely affect the quality of life

Stelfonta is available only by prescription due to the professional expertise required to diagnose MCTs and properly administer it. Additionally, there are instructions for post-treatment care and monitoring the product’s safe use, including treating any adverse reactions.

Possible Side Effects

The most common adverse reactions associated with Stelfonta are wound formation at the tumor site and injection site reactions, such as pain, swelling, reddening of the skin, bruising, thickening, scarring, and some cells’ death in the tissues. In some dogs, there was lameness in the treated leg. Vomiting, diarrhea, hypoproteinemia, and hypoalbuminemia also occurred.

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Be Vigilant as Early Detection is Key

Stelfonta, a Mast Cell Tumor treatment in dogs, is recommended for cancer that has not spread from the primary site. Therefore, as is always essential with cancer in dogs, early detection is vital.

Regular checks could be crucial in identifying any unusual masses or lumps. Vets recommend running your hands over your pet’s body, feeling for any irregularities on the surface of the skin. Also, visually check all areas from their face to the underside of their paws. Additionally, note any change in fur direction or any unusual swelling or redness. These are often signs in dogs with mast cell tumors.

The National Canine Cancer Foundation has developed a useful guide, based on Vets’ valuable input, outlining how to “Check Your Dog“. A good way to remember to check is to have a specific date like the 14th of every month.

Experts agree that older pets are more at risk for MCTs. If your dog is older or one of the susceptible breeds, you should be even more attentive to the possible symptoms. The discovery of early warning signs should prompt a trip to the Vet for a quick diagnosis and a treatment plan.

Dogs with mast cell tumors can still live a long and happy life in many cases!

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