Masitinib Mesylate Treatment of Mast Cell Tumor in a Dog

Mast cell tumors are one of the most common tumors I see on the skin and subcutaneous tissues of dogs although they can occur anywhere. Mast cells are part of the immune system and are found all over the body. Mast cell tumors occur when the inhibitory signal is lost and a mast cell replicates without any control. These tumors grow fast and can be difficult to remove. Malignant cells creep into the surrounding tissues from a tumor making it difficult to get clean margins.

Pictured below is a 9 year old spayed female Australian shepherd mix named Molly. She was always a healthy girl until 4 months ago when she started having respiratory problems. X-rays of her abdomen and chest revealed large tumors.  She needed furosemide therapy to treat the fluid that accumulated in her lungs and chest from the cancer. Tumors also appear on her skin including a small pink mass on her lower right eyelid. The tumor grew quickly into a large ulcerated mass pictured below. Microscopic analysis of her lump revealed a mast cell tumor.

Molly pic09132015

Molly 2 eye pic 09132015

Since surgical removal is not an option for Molly, her family has decided to treat her with masitinib mesylate (Kinavet-CA1) made by AB Science, Chatham, New Jersey. Masitinib is approved for the treatment of nonresectable grade II and III cutaneous mast cell tumors in dogs. It is a tyrosine kinase inhibitor that targets the c-Kit receptor. In dogs who have the c-Kit mutation, the results have been remarkable.

Molly started her treatment on Monday. The tablets are given once a day with food. So far, she is tolerating the medicine well. Please keep your fingers crossed for Molly.


-AB SCIENCE, Kinavet-CA1: Canine Mast Cell Tumor Targeted Therapy, Promotional Materials.

-Shell, Linda. ‘Mast Cell Tumor’ Associate,, last updated 06/06/2011.

Airport Rest Areas for Dogs

Travel with dogs can be a lot of fun.  Especially since more hotels cater to our canine companions. It used to be that finding a place to exercise a dog at an airport was a real challenge. Thanks to the Americans with Disabilities Act provision for service animals, all airports must provide animal relief areas.  At Phoenix Sky Harbor, the Pet Patch is a short walk from baggage claim east of Terminal 2. Terminal 3 has the Paw Pad and terminal 4 has the Boneyard. Unfortunately, all of these exercise yards are outside security.

Pet Patch Skyharbor

Pet Patch 2 Skyharbor

Some airports now provide pet relief areas inside the terminal and even, inside security. On a recent layover at the Dallas Fort Worth airport, I noticed this sign inside terminal D by gate 18.

Airport Dog Run1

I opened the door and found a quiet room with an area of artificial turf. There was even a hose for clean up. There are three outdoor areas with grass located in the lower level of terminal A Gate 8 and at terminal C by gates 2 and 39. Please note these areas are outside of the secured areas. I am grateful that travel for animals is getting easier.

dog airport exercise 2


For more information on traveling with your pet, check out the Dog Jaunt Blog at

You Make The Diagnosis: Dog Iris Abnormality

Pictured below is a closeup of the right eye of a dog. Look closely at the eye and then answer the following questions: Name the abnormal structure found in this eye. Will this condition cause problems? What breeds of dogs are most commonly affected?

Uveal Cyst

Diagnosis: Iridociliary (Uveal) Cyst

Iridociliary cysts are pigmented transparent structures which occur in dogs, cats and horses. The cysts can be attached to the iris as in this patient or free floating. Most are benign and require no specific therapy. On rare occasions, I have seen the cysts grow large enough to block vision. I have also had one patient develop so many cysts that they caused glaucoma (increased ocular pressure). In dogs, the condition is most often seen in Boston terriers, Golden retrievers and Labrador retrievers. They are thought to be caused by trauma or damage to the uveal tract. I have also seen them in pups with congenital cysts.

Uveal cyst red highlight



-Grey, Heather. ‘Iridociliary Cysts’ Associate Database, VIN last updated 10/22/2006.