Lymphoma in dogs

Lymphoma is one of the more common types of cancer diagnosed in dogs. The condition can affect different parts of their bodies, including the lymph nodes, internal organs and tissues.

Although, sadly, lymphoma is usually not considered curable in dogs, treatment can often help control the disease, improve a dog’s quality of life and extend your time together.

What is lymphoma in dogs?

Lymphoma is a type of cancer that affects lymphocytes, which are white blood cells that play an important role in the immune system. 
These cells are found throughout the body, particularly in the lymphatic system. The lymphatic system helps fight infection and includes structures such as lymph nodes, the spleen, thymus and bone marrow.

With lymphoma, abnormal lymphocytes begin multiplying uncontrollably. These cancerous cells can collect in different areas of the body and interfere with normal organ function.

Lymphoma can affect dogs in many different ways. Some dogs develop enlarged lymph nodes, while others have signs linked to the organs affected by the disease.

Causes of lymphoma in dogs

The exact cause of lymphoma in dogs isn’t usually known. Possible factors that may contribute to lymphoma include genetic susceptibility, age-related changes within cells, environmental influences, or abnormal immune system activity.

In most cases, it’s not possible to identify why an individual dog develops lymphoma.

Breeds commonly affected with lymphoma

Lymphoma can affect any dog breed, but some appear to have an increased risk. Some popular breeds reported to be more commonly affected include:

• Boxers
• Golden Retrievers
• Labrador Retrievers
• Scottish Terriers
• English Bulldogs
• Basset Hounds
• Saint Bernards

However, lymphoma can develop in dogs of any breed, including crossbreeds.

Types of lymphoma in dogs

There are several different types of lymphoma, which are classified according to where the cancer develops and the type of lymphocyte involved.

Multicentric lymphoma

Multicentric lymphoma is the most common form of lymphoma in dogs. As the name suggests, it affects multiple lymph nodes throughout the body and often causes noticeable enlargement of the lymph nodes, particularly those under the jaw, in front of the shoulders or behind the knees.

Gastrointestinal lymphoma

Gastrointestinal lymphoma affects the digestive system, including areas such as the stomach and intestines. Dogs with this type may develop symptoms including vomiting, diarrhoea, weight loss or reduced appetite

Mediastinal lymphoma

Mediastinal lymphoma affects lymph tissue in the chest area, particularly around the thymus gland. It may cause breathing difficulties or other signs linked to fluid or pressure within the chest.

Extranodal lymphoma

Extranodal lymphoma develops outside the lymphatic system and can affect areas such as the skin, eyes, kidneys or nervous system. The symptoms depend on which part of the body is affected.

Symptoms of lymphoma in dogs

The symptoms of lymphoma can vary depending on which areas of the body are affected. But some common signs of lymphoma in dogs include:

• Enlarged lymph nodes or lumps under the skin.
• Tiredness or reduced energy.
• Loss of appetite.
• Weight loss.
• Increased thirst or urination.
• Vomiting or diarrhoea.
• Changes in behaviour.
• Fever or appearing generally unwell.

Enlarged lymph nodes are often one of the first noticeable signs. They may feel like firm, painless lumps under the skin, particularly under the jaw, in front of the shoulders, and behind the knees.

Some dogs may appear otherwise healthy despite having enlarged lymph nodes, while others become unwell more quickly.

What to do if your dog shows signs of lymphoma

If you notice unusual lumps, swelling or changes in your dog’s health, arrange an appointment with your vet.

Your vet will examine your dog and may recommend tests to determine the cause. These may include blood tests, urine tests, imaging such as ultrasound or X-rays, and sampling cells from enlarged lymph nodes.

A fine needle aspiration (FNA) is a common test where a small sample of cells is collected using a needle and examined under a microscope. This can help confirm whether lymphoma is present.
If lymphoma is diagnosed, your vet may recommend referral to a veterinary oncologist, a specialist in treating cancer in animals.

Finding a swollen lymph node in your dog doesn't always mean it's cancer

Finding a swollen lymph node in your dog doesn’t necessarily mean they’re suffering from cancer. Swollen lymph nodes can also commonly be caused by inflammation. It’s just important to get all the necessary tests done to discover what’s actually happening.

What age could you expect lymphoma in your dog?

Lymphoma is more common in middle-aged and older dogs, although it can occur at any age. Because lymphoma can cause general symptoms that are shared with many other illnesses, diagnosis may sometimes be delayed.

Regular veterinary check-ups can help identify changes early, particularly as dogs get older.

How to manage lymphoma in dogs

lymphoma focuses on controlling the disease, maintaining your dog’s quality of life and keeping them comfortable. For example, your vet may recommend things like:

• Regular check-ups to monitor your dog’s condition.
• Treatment to slow the progression of lymphoma.
• Managing side effects of treatment.
• Adjusting care based on your dog’s response and wellbeing.

Dogs receiving treatment may need regular monitoring, including blood tests, to assess their health and check how they’re responding.

Your vet will also consider your dog’s comfort and quality of life when making treatment decisions. The aim is to give your dog the best possible quality of life for as long as possible.

Does pet insurance cover lymphoma in dogs?

Pet insurance may help towards the cost of diagnosing and treating lymphoma, depending on your policy and whether the condition is eligible for cover. This can help with costs such as veterinary consultations, diagnostic tests, chemotherapy or other cancer treatments, and medication.

As with most pet insurance policies, pre-existing conditions aren’t usually covered. So, if your dog has signs of lymphoma before taking out insurance, treatment may not be included.

Always check your policy documents to understand what is and isn’t covered.

Lymphoma treatment options for dogs

Treatment for lymphoma is usually done with the goal of improving your pet’s quality of life. Unfortunately, in most cases, lymphoma in dogs eventually goes on to become a fatal illness.

The exact treatment used depends on the type, how advanced it is and your dog’s overall health. Some possible options include:

• Chemotherapy - In rare cases (5-15%) chemotherapy may be curative. However, unlike chemotherapy in humans, treatment in dogs is usually designed to support their quality of life rather than achieve a cure.
• Medication to manage symptoms and improve comfort.
• Steroid treatment in some cases.
• Other supportive care to maintain quality of life.

In some cases, lymphoma may respond well to treatment for a period of time before becoming active again.

It’s worth noting that some pet owners may make the difficult decision not to get their dog treated. This could be because the illness has already progressed significantly, or simply due to the cost of treatment. In this instance, the pet’s survival rate is typically measured in weeks, which is worth being aware of when speaking with your vet about the options.

When to speak to a vet

You should contact your vet if your dog:

• Develops lumps or swelling under the skin, particularly around the lymph nodes.
• Has unexplained weight loss.
• Loses interest in food.
• Seems unusually tired or unwell.
• Has ongoing vomiting or diarrhoea.
• Develops increased thirst or urination.
• Shows changes in behaviour or general wellbeing.

Early veterinary assessment can help identify the cause of these signs and allow treatment options to be considered. If lymphoma is diagnosed, this then allows you to focus on your dog’s quality of life during this tough time and keep them happy for as long as possible.