Cutaneous Mast Cell Tumors

Mast cell tumors are the third most common malignant skin tumors in dogs. There is no know breed or sex predisposition and they are more common in adult to older animals. Mast cell tumors are variable in dogs but generally more well defined tumors present with milder behavior and the poorly differentiated tumors have more aggressive behavior. The most common organs affected by spread of disease are the lymph nodes, spleen, skin, and liver. Mast cell tumors are commonly term the great pretender as they can look like so many different masses. The can be on the skin, under the skin, covered in hair, have no hair, be soft or firm, etc, etc. There is not a standard which is why it is important that any mass that is found be evaluated.

Historically surgery was the only option available to treat mast cell tumors. Surgery is still considered the gold standard of treatment as it allows for staging and prognosis of the tumor. However, since mast cell tumors can grow anywhere surgery is sometimes difficult (think toes, ears, distal limbs, etc). An additional complication is that these types of tumors like to grow roots like trees so a large amount of tissue around and below these masses need to be removed. This sometimes makes surgical removal impossible.

Introducing Stelfonta (tigilanol tiglate injection)! This is an injectable drug that causes necrosis (death of tissue) of 87% of mast cell tumors in 1-2 injections. This is perfect for dogs that are at increased risk of anesthesia or tumors that are in locations where obtaining surgical margins would be difficult (distal limbs).

The other nice thing about stelfonta is that dogs do not need to wear an e-collar or be on exercise restriction! They can lick it….it seems gross and wrong since veterinarians tell clients all the time that wounds should not be licked! It can be a little scary as the tumor continues to die and creates a wound that needs time to heal.

Dog with Great Response to Stelfonta

2 days post injection

20 days post injection

30 days post injection

6 weeks post injection