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Mast Cell Tumours – A short concise guide for dog owners.

Mast Cell Tumours – A short concise guide for dog owners.

Mast cell tumours are a fairly common tumour in dogs and I have been frequently asked about them, the following would be the basis of my normal reply at the first consultation.

1. Histology is essential for two reason, one is to verify that you are actually dealing with a mast cell tumour and two, mast cells are graded on a one to three basis by the histologist and this tells you how things are likely to go in the future.

2. These tumours are graded according to how malignant they are :

A. Grade 1 : Least malignant, surgery alone is likely to resolve it. Good outlook.

B. Grade 2 : More malignant, surgery may resolve the situation, or it may recur other treatment options might be an advantage. Guarded outlook.

C. Grade 3 : Highly malignant, may spread. Poor outlook.

3. The treatment options are :

A. Wide margin excision : if properly carried out and you are only dealing with a single tumour I would have said that about half of mast cell tumours would be permanently resolved in this way.

B. Prednisolone : Mast cell tumours are very sensitive to prednisolone and complete cures and long remissions are possible. This drug is relatively safe and is cheap.

C. Other Chemotherapy : it is possible to use conventional chemotherapy where prednisolone has failed. It is use is controversial and this approach is likely to be a last ditch attempt.

D. Radiation therapy : This is an effective form of treatment for some mast cell tumours, the downside of this therapy is cost.

Plan of action : If I was dealing with a suspect mast cell tumour I would carry out wide margin excision following normal protocols including instrument changes during surgery etc. I would then have histology carried out by an outside laboratory and based on these results I would sit down with the owner and discuss the results, outlook and any future treatment options. I would also check for signs that the tumour had already spread via blood tests and clinical examination.

Scott Nimmo BVMS MRCVS