Canine Cancer

Updated 06 November 2023
Read time: 7 mins

Sadly, cancer is a diagnosis we make all too often in veterinary medicine. Going through a diagnosis of cancer with your pet can be a worrying and uncertain time. There are many different types of cancers that can afflict a dog, some of which carry a more guarded prognosis.


While ‘GP’ vets can usually manage patients during their diagnosis and treatment, it is not uncommon for a dog to be referred to a specialist oncologist. This can be costly and owners may need to travel some distance to the referral centre. It will not be the right choice for everyone.


The most common cancers we see


There are a huge variety of cancers that can affect a dog. Cancer is defined as ‘uncontrollable’ cell growth, and this can occur anywhere in the body. Some of the ones we see most frequently include:


Osteosarcoma. This is an aggressive cancer involving the bone, which is typically diagnosed in large and giant breed dogs such as the Rottweiler and German Shepherd. Signs can include a severe lameness and pain and swelling in the affected area. We can diagnose this cancer with an x-ray and biopsy. Sadly, the prognosis is very poor. Even with surgery and chemotherapy, most dogs won’t survive more than 12 months.


Hemangiosarcoma. This cancer type affects the cells that line blood vessels and we tend to see it affecting the spleen. The growth itself causes minimal symptoms until it ruptures and the dog experiences massive internal bleeding. Dogs can suddenly collapse and will have pale gums and fast breathing. Sadly, while a surgery can be performed to remove the affected spleen, the tumour has usually spread by the time we see the dog.


Mast Cell Tumour. This tumour is also known as ‘the great pretender’ as it can take on many forms. They can be flat or raised and many different colours. We see these tumours most often in the Boxer and Boston Terrier.


Mammary Carcinoma. One of the main reasons I advise neutering for most female dogs is that, when done early enough, it significantly reduces the risk of mammary cancer. Mammary cancers can be aggressive and may spread to places like the brain and lungs. They usually grow near the nipple and can be sized anywhere from a pea to a basketball.


Lymphoma. Lymphoma begins in the immune system and signs can include swollen lymph nodes, weight loss and increased thirst. Any swollen lymph nodes should be sampled. When found early, many forms of lymphoma can be treated with a favourable outcome.


Testicular Cancer. When a dog is not castrated, a new lump on their testicle is something we must pay attention to. Testicular cancers are not uncommon. When found early on, castration is usually curative.


Signs of cancer


There are a huge range of signs that can be caused by canine cancer and the signs we see will depend on the type of cancer involved. Some animals may simply have a mass or lump, while others will experience symptoms including excess thirst, weight loss, coughing, limping or vomiting.


It all depends on where the mass is located and how large it is. While benign (non-cancerous) growths don’t tend to cause any symptoms, if they are growing within the brain or chest cavity, they are likely to make a dog very unwell.


How is cancer diagnosed in a dog?


Any new lump or bump should be mentioned to your vet. The rule of thumb is that a mass that has been there for more than two weeks, or that is growing or changing, should be evaluated.


If concerned, the vet will likely sample the lesion. A Fine Needle Aspirate (FNA) is when a needle is put into the growth and cells are aspirated and looked at under the microscope. This can be done in a conscious animal and does not usually require sedation (depending on where the mass is).


A biopsy is when a larger sample is analysed and most dogs will be sedated or put under anaesthetic for a biopsy to be taken. A stitch or two will usually be needed to close the skin after. A biopsy is generally more accurate than an FNA and provides more information.


Cancers of the blood and immune system are sometimes detected from a blood test and/or blood film analysis.


Imaging tools such as X-rays, CT scans and ultrasound are used to help in the staging of cancer.


Can cancer be treated?


Many types of cancer can be treated. In some cases, we achieve a full cure. For other dogs, we may get them into a state of remission.


We will sometimes offer ‘palliative treatment’. This is when our aim is to keep the patient comfortable but we are unable to cure the disease. Some owners decline cancer treatment (perhaps for ethical reasons, due to the cost or because they feel it would be too much for their dog) and opt for palliative care instead.


Cancer treatment may include surgery, chemotherapy and/or radiotherapy.


Whether or not your dog is a good candidate for treatment will depend on many factors including their age and general health status as well as the stage and type of cancer involved.


Are any breeds more at risk?


Due to genetics, there are certain dogs that are known to be a lot more prone to cancer than the average canine.


This includes breeds such as the:


  • German Shepherd
  • Labrador
  • Golden Retriever
  • Boxer
  • Bernese Mountain Dog


However, many of these dogs will never get cancer and it can affect any breed including cross-breeds.


Breeders should be aware of the genetic cancers present in their breed and should always aim to breed those not thought to be susceptible.


How to help your dog at home


If your dog has been diagnosed with cancer and is awaiting treatment or currently undergoing it, you may want to know how you can keep your dog comfortable at home.


  • Allow them to rest as much as they want. Ensure they have a cosy bed and a quiet space where they can relax uninterrupted.
  • Consider offering some supplements. Depending on the cancer type, supplements such as turmeric, mushroom extract, milk thistle and fatty acids may provide some benefit.
  • Support their immune system with a premium diet containing fresh ingredient, probiotics and anti-oxidants.
  • Make sure they are taking all of their prescribed medicine when they should. Missing even one dose of pain relief can have a serious knock-on effect.
  • Provide all of the love and support that they need.
  • Keep in regular touch with your vet; if you have concerns or feel your dog is going downhill, it is important your vet is made aware promptly.



What can I do as an owner to keep my dog safe?


For most owners, their main question is how can cancer be avoided? Sadly, most types of cancers are not something we can prevent. However, it can help to:


  • Neuter your dog . The timing of which depends on the individual and should be discussed with your vet. For most, it will be recommended between the ages of 6 and 24 months.
  • Avoid obesity and keep your dog a healthy Body Condition Score.
  • Provide a high quality premium dog food such as those on offer from Pooch & Mutt.
  • Avoid smoking near your dog.
  • Minimise the use of chemicals, pesticides and harsh cleaning products in your home and garden.
  • Regularly check your pet for new lumps and bump or other symptoms of concern.
  • Bring your dog for regular vet checks. For seniors, these checks should be every 6 months.


Comments (2)

I have enjoyed reading your vet’s informative blog even though I have had 5 boxers who suffered from mast cell tumours and one with Hemangiosarcoma. I am now on my 7th boxer and fingers crossed he will live to a good age. My first boxer who had a brilliant pedigree died at 5 from the Hemangiosarcoma but the others managed to get to 11, 12 and 13 with chemotherapy so not bad ages considering. Thank you vet Linda.

Sue Marshall - May 25 2022
Pooch Admin

Dear @Sue, thankyou for your lovely comment, we will pass this on to Vet Linda. Take Care!

Team Pooch - May 25 2022

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