Mammary masses are growths that occur on the mammary tissue (breasts).
Whilst these are often benign (harmless) they can also be malignant (cancerous).
These masses can start off the size of a pea and grow to considerable size.
They can be a single mass or multiple small masses. Often these smaller growths are grouped together and feel similar to a small bunch of grapes.
Early diagnosis and treatment are essential.
What causes mammary masses?
As with humans, hormones can play a large part in the development of mammary masses.
Female dogs (Bitches) who have not been spayed have a much higher chance of developing mammary masses.
What can I do to prevent this happening to my dog?
There is good evidence to suggest that spaying before the first or second season can significantly reduce the risk of mammary masses.
Checking your dog for lumps can help with early detection, and is a very good excuse for more belly rubs!
What should I do if I find a lump on my dog’s mammary tissue?
The first thing you should do is take your dog to your vet. They will usually take a small sample of the mass (a biopsy) to be sent to the lab. This might be taken with a small needle or a section might be surgically removed with your pet under a general anaesthetic.
If the lab tests say the mass is benign then you may be asked to monitor it closely or you will be offered removal by your vet.
However if the mass is malignant your vet will want to check for any metastasis (spread/development of secondary growth). The most common site for mammary masses to spread is to the lungs, therefore a chest x-ray might be suggested. Your vet may also need to perform more tests or take more samples from other areas such as the lymph nodes.
What is the treatment?
Surgically removing a mammary mass is the best treatment option. Sometimes multiple mammary glands will need to be removed if the mass has spread.
If the growth is malignant and has spread to the lungs there is sadly very little that can be done in most cases. Further research is ongoing and hopefully an effective treatment can be developed.
What is the prognosis?
With a benign mammary mass surgical removal will usually lead to a full recovery.
If your dog has a malignant mass survival times will depend on the extent of spread and the type of tumour. The tests performed by your vet will help give you a better idea of what to expect.