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Lymphoma in Dogs: A Comprehensive Guide

Nearly everyone in today's world has been affected by cancer to some degree. Either you have battled the vicious disease yourself or you know someone who has.

It's a tragic part of our lives, yet it has been somewhat normalized in a sense due to the fact that is it so extremely common.

Sadly for our dogs, cancer doesn't discriminate. Just like people, many dogs will also have to face the disease in its various forms. In fact, studies estimate that over 25% of all dogs will be diagnosed with cancer at some point in their life.

Up to 50% of dogs over the age of 10 will die from the disease. This is a beyond staggering number. Therefore, it is important that dog owners are aware of the telltale signs in order to recognize the condition before it's too late. 

While there are many forms of cancer, lymphoma is the most commonly diagnosed cancer in dogs. Therefore, understanding canine lymphoma will help pet parents to be able to quickly recognize symptoms and act efficiently in getting their dog the help they need.

We know that a cancer diagnosis can be absolutely heartbreaking. However, by understanding your dog's condition, you can make informed decisions with their happiness and wellbeing in mind.

lymphoma in dogs

What is Lymphoma in Dogs

Lymphoma is a commonly diagnosed cancer in people and dogs alike. Many veterinarians compare canine lymphoma to non-Hodgkin’s lymphoma in people.

In fact, the two conditions are so similar that nearly the identical chemotherapy protocols are used to treat both dogs and humans.

Lymphoma is a blanket term used to diagnose cancers that stem from white blood cells called lymphocytes. These white blood cells help the dog's immune system to effectively fight off infections.

Lymphocytes are found in high volumes in areas of the body such as the lymph nodes, the spleen, and within the bone marrow. It is important to note that lymphoma can exist anywhere in the body. However, it is found most prominently within the organs where the lymphocytes are found in high concentrations.

There are over 30 types of lymphoma in dogs making up for approximately 10-20% of all cancers diagnosed.

lymphoma in dogs

What is Lymphosarcoma or Non-Hodgkin’s Lymphoma 

You may hear lymphoma also referred to as lymphosarcoma or non-Hodgkin’s lymphoma. We'll cover more detail on terminology in a moment!

What are Lymphocytes 

To reiterate, lymphocytes are the white blood cells responsible for supporting the immune system against infection.

What are Low Lymphocytes 

When you hear that your dog has a low lymphocyte count, it means they are highly susceptible to infection and disease. Low lymphocytes are often associated with cancers such as lymphoma.

Low Lymphocytes

Types of Lymphoma in Dogs

There are over 30 different types of lymphoma in dogs. The type of lymphoma will determine how quickly it progresses, possible survival rates, as well as clinical signs and symptoms to look for.

Of the 30 different types of the disease, the four most common types are:

  1. Multicentric lymphoma
  2. Alimentary lymphoma
  3. Mediastinal lymphoma
  4. Extranodal lymphoma

Multicentric Lymphoma 

Of the four types of lymphomas that we will be covering, multicentric lymphoma is by far the most common.

In fact, multicentric accounts for 80-85% of lymphomas in dogs. Multicentric lymphoma affects the dog's lymph nodes. In many cases, the primary physical symptom is visibly enlarged lymph nodes, sometimes up to ten times their normal size.

The enlargement typically doesn't cause your dog any pain, thus making an early diagnosis extremely difficult. 

Alimentary Lymphoma 

Alimentary lymphoma is the second most common type of lymphoma in dogs, although it only accounts for less than 10% of diagnoses. Canine alimentary lymphoma primarily affects the dog's intestines.

Therefore, the symptoms of alimentary lymphoma in dogs are gastrointestinally related as the disease causes intestinal lesions (more on symptoms in a moment).

Mediastinal Lymphoma 

In rare cases, canine mediastinal lymphoma will be diagnosed. This form of lymphoma causes either the thymus and/or the mediastinal lymph nodes in the dog's chest to become enlarged.

The enlargement is a result of high-grade malignant T-lymphocytes.

Extranodal Lymphoma 

Finally, the fourth most common form of lymphoma is extranodal lymphoma. This type of the disease affects a specific organ (i.e the eyes, kidneys, lungs, skin, central nervous system, etc.).

The most common organ that is affected by extranodal lymphoma is the skin. This form of the disease is also referred to as cutaneous lymphoma. Symptoms of extranodal lymphoma will vary greatly depending on which organ is affected. 

What Causes Lymphoma in Dogs

Even with advanced studies available, there are still many things that are unknown when it comes to cancer in humans and dogs alike. Experts aren't able to pinpoint the exact cause of lymphoma in dogs, although studies have found that there are in fact certain breeds who are at a higher risk of the disease.

Furthermore, when genetics don't play a role in the lymphoma diagnosis, we must assume that an environmental component is involved. Let us explain.

Environmental Toxicity 

Studies have found that certain breeds at a predisposition for the development of canine lymphoma (more on that in a moment).

However, when so many breeds not included on the high-risk list are also developing the disease, experts must consider other possibilities of the underlying cause.

What do all of these dogs have in common, other than lymphoma? In many cases, the answer is their environment.

Pet parents may not fully realize how their dog's day to day environment includes a substantial amount of toxins that can greatly affect their dog.

Toxicity from things like paints or solvents, as well as pesticides, herbicides, and insecticides can all play a massive role in your dog's immune system health. In many cases, experts are linking these toxins to diseases such as cancer.

lymphoma in dogs can come about because of paint

Additional possible causes of canine lymphoma include:

  • Viruses and/or Bacteria
  • Genetics
  • Weakened Immune System

Breeds at Higher Risk for Canine Lymphoma

Studies show that the current breeds are at a higher risk of canine lymphoma:

  • Rottweilers
  • Scottish Terriers
  • Basset Hounds
  • Airedales
  • Saint Bernards
  • Golden Retrievers
  • Bullmastiffs
  • Boxers
  • Bulldogs

Additionally, studies have found that certain breeds including Dachshunds and Pomeranians have a lower risk of developing canine lymphoma.

Canine lymphoma is also most commonly diagnosed in middle-aged dogs, approximately 6-9 years old.

With that said, it is important for dog owners to understand that any dog, no matter what breed, may develop lymphoma.

Being able to recognize the symptoms of the disease will help expedite an accurate diagnosis and determine the best form of treatment for your dog's individual needs.

Lymphoma Symptoms 

The symptoms of canine lymphoma will vary based on the type of lymphoma that your dog has. Unfortunately, this can make an early diagnosis more difficult in some cases.

General Symptoms of Lymphoma 

In most cases, regardless of the type of lymphoma, the following general symptoms will be present.

  • Swollen lymph nodes under the jaw, in front of the shoulders, or behind the knees
  • Swelling of the face
  • Swelling of the legs
  • Excessive thirst
  • Excessive urination

lymphoma in dogs

Multicentric Lymphoma Symptoms 

When it comes to the most commonly diagnosed form of lymphoma, multicentric lymphoma, the first symptom that pet owners will recognize is typically swollen lymph nodes.

In many dogs, it is common for the lymph nodes to swell up to ten times their normal size. While it looks painful, the swollen lymph nodes do not typically cause the dog any distress. They will feel like rubbery lumps and will be able to move freely under the skin.

As multicentric lymphoma progresses, dog owners will also notice the following symptoms:

  • Lethargy
  • Lack of appetite and weight loss
  • Fever
  • Weakness
  • Dehydration

Alimentary Lymphoma Symptoms 

Alimentary lymphoma attacks the dog's intestines. Symptoms of alimentary lymphoma are a result of gastrointestinal lesions and often involve:

  • Vomiting
  • Diarrhea
  • Lethargy
  • Anorexia
  • Severe abdominal pain and sensitivity
  • Weight loss

lymphoma symptoms

Mediastinal Lymphoma Symptoms 

Mediastinal lymphoma causes a large mass to develop in the chest. Therefore, a common symptom of the disease is difficulty breathing. Additional symptoms include:

  • Swelling of the face
  • Swelling of the front legs
  • Increased thirst
  • Excessive urination

Mediastinal lymphoma in dogs can also cause a muffled heart sound which your veterinarian will be able to hear with a stethoscope.

Extranodal Lymphoma Symptoms 

Lastly, symptoms of extranodal lymphoma in dogs will ultimately vary depending on which organ is being affected.

For example, extranodal lymphoma that affects the lungs will often cause respiratory problems to develop. Extranodal lymphoma that affects the eyes can lead to blindness. When extranodal lymphoma affects the kidneys, it can lead to renal failure. 

Cutaneous Lymphoma 

The most common type of extranodal lymphoma, cutaneous lymphoma, affects the skin and, therefore, the associated side effects also affect the skin.

Many times pet owners will find single or multiple raised nodules or scaly lesions on the dog's body, both of which are telling signs of cutaneous lymphoma.

The raised bumps can also be found in the dog's mouth, specifically on the gums, lips, or the roof of the mouth. It is common for the disease to be mistaken for an allergy for several months before an accurate diagnosis is made.

Additional symptoms of cutaneous lymphoma include:

  • Dry, red, flaky patches of skin
  • Large masses or tumors
  • Development of skin ulcers

How is Lymphoma Diagnosed

Diagnosing lymphoma early on can be rather difficult as the disease often doesn't cause the dog any pain unless it is affecting the bones. Therefore, by the time the dog receives a diagnosis, the disease can be quite progressed.

Typically, a series of diagnostic tests will be the first step in order to accurately diagnose lymphoma in dogs. These diagnostic tests include:

  • Blood tests
  • Fine needle aspirate* of the tumor
  • Biopsies
  • X-rays
  • Ultrasounds
  • Complete blood count (CBC)
  • Urinalysis
  • Blood chemistry panel
  • Abdominal sonograms

lymphoma in dogs is diagnosed through x-rays

What is a Fine Needle Aspirate 

The most common diagnostic tool used to accurately diagnose lymphoma in dogs is something called a fine needle aspirate.

The procedure allows veterinary oncologists (veterinarians who specialize in cancer patients) to safely remove a small sample of dog’s lymph nodes or affected organs.

Once removed, the vet will be able to examine the sample through either a cytology exam or through a histopathologic tissue evaluation.

Stages of Lymphoma in Dogs

The World Health Organization developed a system for staging lymphoma in dogs. During the diagnosis process, your vet will label your dog's disease as being one of five stages. Treatment and prognosis will ultimately depend on which stage is diagnosed.

  • Stage I: Single lymph node is involved
  • Stage II: Multiple lymph nodes within in the same region are affected
  • Stage III: Multiple lymph nodes in multiple regions affected
  • Stage IV: Liver and/or spleen involved (it is possible to not have lymph node involvement although in most cases there is)
  • Stage V: Bone marrow or blood involvement and/or other organs other than liver, spleen and lymph nodes affected

Substage Categories 

Additionally, veterinarians will also label the disease as either substage A or substage B.

Substage A is labeled if the dog shows no sign of illness. Substage B is labeled if the dog does show signs of illness.

Treatment for Lymphoma 

Unfortunately, there is presently no known cure for canine lymphoma. With that said, it is by far the most treatable type of cancer in dogs. Most commonly, chemotherapy is the preferred treatment option.

Chemotherapy is also proven to be the most effective when it comes to canine lymphoma. The type of chemotherapy treatment will vary based on the type of lymphoma.

For example, multicentric lymphoma in dogs is often treated with chemotherapy protocol UW-25.

Your veterinary oncologist will be able to walk you through exactly which treatment method is best for your dog's individual needs.

Chemotherapy for Dogs VS Chemotherapy for People 

As we previously mentioned, lymphoma in dogs is often compared to non-Hodgkin lymphomas in people. Interestingly enough, the treatment for both (varying chemotherapy methods) is also closely related.

Fortunately for our dogs, chemotherapy doesn't negatively affect them nearly as negatively as it does people. Chemotherapy doesn't typically make dogs feel sick and dogs generally don't lose their hair. 

Dogs with thick fur such as Poodles, Old English Sheepdogs, and the Bichon Frise may lose more hair than most. 

Side Effects of Chemotherapy in Dogs

The following are side effects associated with chemotherapy in dogs:

  • Lethargy
  • Lack of appetite
  • Mild bouts of vomiting and/or diarrhea

Additional Treatment for Lymphoma 

Depending on the type of lymphoma and the stage of the disease, radiation therapy and/or surgery may be recommended.

Additionally, your veterinarian may recommend things like dietary changes, physical therapy, or nutritional supplements in order to provide extra support during treatment. 

Lymphoma Survival Rate

Of course, one of the leading questions that pet parents have about their dog's diagnosis is what they should expect in terms of survival rate and life expectancy. Unfortunately, the answer is not always clear and simple. Lymphoma in dogs will vary greatly case to case.

The prognosis will ultimately depend on the type of lymphoma as well as the stage in which it was diagnosed. The prognosis for lymphoma in dogs will also depend on the treatment option chosen.

For instance, if the pet owner cannot afford or chooses not to use a treatment like chemotherapy, it can greatly affect the dog's projected life expectancy.

lymphoma in dogs survival rate

Remission vs Cure

It is also imperative that pet owners realize that there is a difference between complete remission and a cure. Total, complete remission means that there are no clinical signs or symptoms of cancer.

However, cancer could still exist in the body. A cure means that the body is completely free of the disease. Partial remission also exists and is a term used to describe a patient that shows some, not all, signs of cancer.

Additionally, research has found that certain dogs tend to have a better prognosis. For instance, studies show that neutered females have better prognosis and longer survival times.

Lymphoma in Dogs: A Final Thought

At the end of the day, receiving a lymphoma diagnosis can be an impossibly challenging time in a dog owner's life. We want our canine friends to live forever and with a lymphoma diagnosis, it can seem like our time with them is stopped in its tracks.

Trust us, we know how difficult it is and we are truly so sorry that some of our readers are going through this.

With that said, we want pet owners to understand that canine lymphoma is by far one of the most treatable cancers in dogs.

Every day, advancements in science and holistic medicine are making great strides forward. So many canine cancers that were once considered to be a death sentence are now being cured. Lymphoma is among these diseases.

One of the most important things that dog owners can do is to stay alert. By understanding your dog's normal day to day behavior and tendencies, you'll be able to pick up on when something isn't right.

Furthermore, if and when you notice that something is off with your dog, don't delay in getting your dog an accurate diagnosis. A timely trip to the vet can make a world of difference for your furry companion.

From all of us at Honest Paws, we hope your beloved four-legged friend gets well soon.


Fabiana Pineda

Fabiana is a caring pet owner who also works as the Lead Editor of CertaPet. She enjoys helping other pet parents get all the furry-friend-related-info they need, as well as spending time with her precious pooch.

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