As an experienced veterinarian, I’ve had the privilege of caring for countless pets and witnessing the profound bonds they share with their families.
During one such consultation recently, we surprised a client with a diagnosis of mammary neoplasia, a type of tumour that affects the mammary glands.
Any time the word ‘tumour’ is used, it can sound daunting, but here is where early detection and treatment can make a significant difference. Understandably, our client had a lot of questions, so in this blog post, we’ll explore what mammary neoplasia is, how to recognise the signs, and the steps you can take to ensure your furry friend receives the best care possible.
Whether you’re a seasoned pet owner or new to the joys of pet parenthood, understanding this condition can help you and your pet more effectively.
Let’s dive in.
What is mammary neoplasia?
Mammary neoplasia is one (or multiple) cancerous tumours that affect the mammary (breast) tissue of both dogs and cats.
They’re the most common type of tumour in (not desexed) female dogs and are commonly seen in dogs older than 6 years.
This type of tumour is less common in cats, but when present, are more likely to be aggressive.
Benign tumours
In some cases, the tumours are benign and slow-growing, with a low chance of spreading to other parts of the body.
Malignant tumours
However, if a malignant tumour is present, the cells can spread to other areas of the body, often starting locally by spreading to the lymph nodes and potentially spreading to organs such as the lungs.
Note: Benign tumours can also become malignant over time, so don’t discount them if your original diagnosis is ‘benign’.
Interesting facts:
- As with humans, mammary neoplasia can affect both male and female dogs.
- These tumours are often hormone-dependent, meaning they can be prevented through desexing your pet.
Symptoms of a mammary neoplasia and what to look for
The most typical symptom, and what’s most often presented in our clinic, is a small lump in the mammary tissue. Occasionally, tumours will be more advanced and be quite large. In these cases, they create a swelling that protrudes from the dog’s (or cat’s) ‘belly’.
Tumours can also be ulcerated and oozing fluid or pus (typically if they have remained untreated for a long time).
If your pet’s tumours are particularly aggressive or remain untreated, owners may notice a cough or lameness in their animal. This could indicate the tumour has spread to another area of the body.
How to prevent mammary neoplasia
Consider having your cat or dog desexed. We recommend this procedure in most circumstances. You can discuss with your vet the best time to do this for your pet’s age and health.
Secondly, check your dog or cat’s mammary glands regularly.
Remember to ask your vet to check the mammary glands when you are in for annual health checks so that smaller or unusual swellings can be examined thoroughly.
Vet Treatment for mammary neoplasia
We discuss your pet’s history, including previous pregnancies, lumps in the mammary tissue, and signs you have noticed at home.
Then, we complete a thorough exam to determine if all body systems are in working order.
If lumps are found, we discuss further diagnostics, including a blood test, sampling of the tumour (either using a needle to obtain a small number of cells from the area or a biopsy), radiographs, and potential plans for surgery, if required.
If you feel your cat or dog may have a lump and are concerned about mammary neoplasia, please organise an appointment to see your vet as soon as possible. Early intervention is key. If your pet is not yet desexed and you have questions about it, we have a great post here about when is the best time to desex your cat/dog or this post – why is desexing so important?
If you have questions or would like to book an appointment, please give our team a call, as we’re happy to help wherever we can.



