Understanding cancer of the salivary glands in dogs

The word “cancer” is one that is very daunting for dog owners facing a potential diagnosis from the vet, and there are a huge number of different types of cancers that can affect different parts of the body.

One of the less common but potentially more serious types of cancer that can affect dogs is cancer of the salivary glands, which develops inside of the mouth and usually occurs in elderly dogs.

Because salivary gland cancer in dogs is not very commonly seen and shares symptoms with a wide range of dental issues and other disorders of the mouth, it can be one of the more challenging cancers to recognise and diagnose.

Older dogs are more prone to developing salivary gland cancer – but they are also more prone to the effects of dental decay and poor oral hygiene, which can both mask more acute issues like cancer, and display with common symptoms and so, make diagnosis more challenging.

In this article we will examine salivary gland cancer in dogs in more detail, including the symptoms of salivary gland cancer, what sort of dogs are more prone to developing it, and what can be done to treat or manage the condition in affected dogs.

Read on to find out more about canine salivary gland cancer.

What is cancer of the salivary glands in dogs?

The salivary glands are located inside of your dog’s mouth and as the name implies, they are responsible for producing saliva. Saliva helps to cool your dog down, lubricate the mouth and digestive tract, and it also contains enzymes that get to work on breaking down the food your dog eats before it even reaches their stomach.

All dogs have four separate salivary glands inside of their mouths, and any one of the four can develop cancerous tumours.

There are two different types of salivary gland cancers that can affect dogs, which are the more common variant, called adenocarcinomas, and the less-common salivary gland carcinomas.

These two different types of cancers grow at different rates, and so the onset and spread of salivary gland cancer in dogs can range from sudden and acute, to longer-term and slower growing.

However, both types of salivary gland tumours in dogs can metastasize or spread to other areas of the dog’s body, including the lungs, throat and lymph nodes throughout the body.

What sort of dogs are at greatest risk for salivary gland cancer?

As mentioned, salivary gland cancer is a rare cancer in dogs as a whole, and whist it is something your vet will need to consider when reaching a diagnosis based on your dog’s symptoms, it remains uncommon in dogs of all types.

However, some dog types have higher risk factors for salivary gland cancers than most others, most specifically, dogs in old age. The average age of diagnosis of salivary gland cancer in dogs is ten years or over, with the risks increasing exponentially as the dog ages further.

Both male and female dogs are equally likely to be affected, and neutering doesn’t play a part in reducing the risk.

Some dog breeds seem to present with more cases of salivary gland cancer than others, although within even these breeds, the condition remains rare. The poodle and various spaniel breeds including the cocker spaniel are thought to have slightly higher risk factors for salivary gland cancer in old age than other breeds.

The symptoms of salivary gland cancer in dogs

Salivary gland cancer develops within the dog’s mouth, and so your vet will need to consider and rule out a range of other potential causes for the dog’s symptoms before they reach a formal diagnosis.

The potential symptoms of salivary gland cancer in dogs that you may notice at home are listed below, but all of these symptoms can also be caused by other problems as well that are generally less serious, so don’t panic if your dog seems to be displaying several of them – but do make an appointment with your vet.

Salivary gland cancer symptoms in dogs may include:

• Foul breath, particularly if this develops quite quickly and the dog’s teeth and gums appear to be in good condition.
• Pain or discomfort when swallowing food or water, or refusal or reluctance to eat.
• Slobbering, drooling or hypersalivation that is out of character for the dog or dog breed in question.
• Gradual, unexplained weight loos.
• Pained or laboured breathing.
• In extreme cases, salivary gland cancer can even change the appearance of the dog’s eyes, potentially causing one eye to protrude more than the other.

Can salivary gland cancer in dogs be treated successfully?

Salivary gland cancer in dogs can be challenging to treat, because it is often not diagnosed until it is quite advanced. Additionally, because it tends to develop in elderly dogs, they may be unsuitable for some forms of treatment that might be viable in younger dogs, due to the added risks that come with advanced age.

If the cancer is detected early enough and before it has begun to spread, surgical removal of the affected salivary gland is usually the preferred option. As dogs have four salivary glands in their mouths, removal of one of them doesn’t tend to cause problems with future saliva production.

If the cancer has spread significantly or if surgery is otherwise not an option, your vet may wish to try treatment with chemotherapy or radiotherapy, which may shrink the size of the tumours, prevent them from spreading further, improve the dog’s quality of life, and lengthen their lifespan.

Such methods rarely result in the full eradication of the cancer and complete remission, but this is a theoretical possibility.

If treatment is ineffective or if your vet doesn’t think it is possible to treat the cancer without harming the dog’s quality of life beyond a viable threshold, they may advise palliative care with painkillers and other medications to keep your dog comfortable.

When the cancer progresses to the point that this in itself makes the dog’s quality of life too poor to be tolerable, a decision is usually made to euthanise the dog to prevent further suffering.