Mast Cell Tumours In Dogs

By Dr Phil Sacks

I  have treated 100’s of Mast cell tumours in dogs in private veterinary practice as they are one of the most common tumors in dogs and in my experience extremely common especially  in Staffies, Pit bulls, Boxers.

Mast cells are tissue cells that live for about 40 days , and they come from the Bone marrow

Mast cells are filled with histamine –cause the allergic reaction; and  Heparin makes them bleed a lot, attractive to eosinophils and enzymes to break down wounds after surgery

Location :

95% on skin or just under the skin

50% on trunk, 40 % on leg < 1 % in spleen liver and kidneys

Supportive therapy when treating Mastocytomas in dogs

Antihistamine pre-surgery

• H2 antagosits like Ranitidine or Famotidine
• H1 Diphenhydramine

Diagnosis of Mast Cell tumour in dogs

Very  easy on Cytology of a fine needle aspirate of the mass .  This is examined  under the microscope while the owners waits during the consultation and a diagnosis confirmed.

We recommend aspirating the regional lymph node prior to surgery to determine if the mastocytoma has spread.  It is also a good prognostic indicator.

One in four dogs gets a second MCT in their life.

Therapeutics – treating a mast cell tumour in a dog 

Wide surgical excision with clean margins easiest!

Radiation therapy – Definitive radiation therapy daily for 3 weeks!! – Usually curative

Chemotherapy = radiation if dirty margins or spread – Vinblastine and Prednisilone therapy with or without radiation is an option.

Systemic therapy – Thyrosine Kinase Inhibitor – Palladia

Masivet – for non surgical MCT – active is masitinib. also a TYROSINE KINASE INHIBITOR Due  to its spectrum of inhibition, Masivet® has demonstrated efficacy in the treatment of mast cell dysfunctions and its related complications. This range leads to masitinib having further potential indications like atopic disease.

Palladia – Tocerab  2.5 – 2.75mg /kg at a three times a week dose on Mon/Wed/Fri dose rate

Can not stop  Palladia once its working –ever  – yes its lifelong! Like marriage ! but Expensive – $450 per month great for hard to reach places or owners to say good bye.

Dr Phil is a Senior Fellow of the University of Melbourne faculty of Veterinary Science and is accredited by AQIS (Australian Quarantine and Inspection Service)