Canine Lymphoma: Symptoms, Diagnosis, and Treatment

Canine lymphoma is a malignant tumor in the lymph nodes or lymphatic system that arises from lymphoid tissues, primarily lymphocytes. Canine lymphoma develops when lymphoid cells multiply uncontrollably and pathologically. The four types of dog lymphoma are multicentric, alimentary, mediastinal, and extranodal, each with a unique behavior. 

Canine lymphoma in dogs is caused by genetics, environmental factors like pollution exposure and strong magnetic fields, and germs such as bacteria and viruses. Sex, breed, and neuter status are the main lymphoma risk factors, with intact male Boxers most commonly affected. 

Enlarged lymph nodes, facial swelling, skin changes, stomach issues, difficulty breathing, weight loss, and lethargy are common symptoms in lymphoma dogs.  

The standard treatment for dog lymph nodes cancer is chemotherapy. Chemotherapy is combined with radiation and surgery in some cases. Some lymphoma cancer dogs benefit from alternative treatment options, such as CBD oil.  

Canine lymphoma is not curable. The goal is remission, which temporarily stops all cancer symptoms and prolongs the dog’s lifespan. 

What is Canine Lymphoma in Dogs?

Canine lymphoma in dogs is a group of malignant cancers stemming from white blood cells called lymphocytes, which are a part of the immune system. 

Lymphoma involves any part of the dog’s body, but it is most prevalent in lymphoid tissues, including the lymph nodes, thymus in young puppies, spleen, and liver. 

Dogs develop over 30 different types of lymphoma, but multicentric or systemic lymphoma is the most frequently diagnosed, accounting for 80 - 85% of lymphoma in dogs. Multicentric lymphoma affects lymph nodes throughout the body.

Dog lymphoma is classified into five stages. Stage 1 involves a single lymph node or lymphoid tissue from a single organ. 

Stage 2 involves multiple lymph nodes in the body's front or back. Stage 3 involves multiple lymph nodes in the front and back of the dog's body. 

Stage 4 involves the liver or the liver and spleen. Stage 5 involves the bone marrow and the nervous or gastrointestinal system. 

Determining the stage of canine lymphoma in dogs is an important prognostic factor. Lymphoma in dogs is fatal, but with treatment, many dogs go into remission and live for up to a year after the initial diagnosis. 

What are Other Terms for Canine Lymphoma in Dogs?

Other terms for canine lymphoma in dogs are malignant lymphoma and lymphosarcoma. The prefix malignant describes the nature of the tumor, meaning it is invasive and metastasizing. 

The term lymphosarcoma is a non-specific umbrella term that includes all malignant tumors arising from lymphatic tissue. 

Lymphoma is sometimes called by the organ it affects. Cutaneous dog lymphoma involves the skin, and alimentary lymphoma affects the gastrointestinal tract. 

How does Canine Lymphoma Develop?

Canine lymphoma develops when lymphoid cells multiply uncontrollably and pathologically. The process starts in the B-cells or T-cells. 

Lymphoma progresses to primary and secondary lymphoid tissues, including lymph nodes, bone marrow, thymus, and spleen. 

The age at which dogs develop lymphoma varies. Boxers get lymphoma when they are seven to fourteen years old, Bullmastiffs between four and six, and Bulldogs when they are less than three years old. 

It is not fully understood how do dogs get lymphoma, but a complex interaction of environmental and genetic factors is believed to be the cause. 

How Common Is Canine Lymphoma?

Canine lymphoma is extremely common. Lymphoma is one of the most prevalent cancer forms in dogs. Around 7 to 14% of all cancer cases are lymphoma, according to “Canine Lymphoma Research,” published by the Purdue University College of Veterinary Medicine. 

There are over 30 types of lymphoma in dogs, and some are more common than others. Multicentric or systemic lymphoma is the most common, while alimentary lymphoma is very rare. 

“Alimentary lymphoma accounts for approximately 5% of cases,” says a study, “Alimentary Lymphosarcoma in a 4-Year-Old Labrador Retriever,” published in the Canadian Veterinary Journal in 2004. 

Lymphoma is common in cats, too, accounting for 30% of all feline cancer cases. Intestinal lymphoma is the most frequent lymphoma in cats. 

What Breeds are More Prone to Developing Canine Lymphoma?

The breeds more prone to developing canine lymphoma are listed below. 

• Boxers: Boxers are the number one dog breed prone to developing canine lymphoma. Boxer breeds are prone to T-cell lymphoma and are diagnosed between seven and 14 years of age. 
• Labrador and Golden Retrievers: Retrievers are the second risky breed prone to canine lymphoma. High-grade T-cell lymphoma in Golden Retrievers and Labradors is widespread. 
• Rottweilers: Rottweilers are susceptible and tend to develop B-cell lymphoma in most cases. 
• Bulldogs: Bulldog breed members have an increased incidence of canine lymphoma, with most dogs diagnosed under three. 

What are the Different Types of Lymphoma in Dogs?

The different types of lymphoma in dogs are listed below. 

• Multicentric: Multicentric or systemic lymphoma affects lymph nodes in body parts and is the most common type, accounting for 80 to 85% of all lymphoma cases.
• Alimentary: Alimentary lymphoma involves the dogs' gastrointestinal tract and is the second most frequent canine lymphoma type.
• Mediastinal: Mediastinal lymphoma in dogs is a rare type affecting lymphoid chest tissues such as the thymus and lymph nodes.  
• Extranodal: Extranodal lymphoma targets specific organs not belonging to the lymphatic system, such as eyes, lungs, kidneys, skin, or nervous tissues. 

What does Canine Lymphoma Look Like?

Canine lymphoma in dogs looks like swollen lymph nodes. The exact overall appearance varies based on the lymphoma type. Cutaneous lymphoma is the most common striking. 

The skin of dogs with cutaneous lymphoma looks dry, red, and flaky. The skin becomes thick, moist, and ulcerated as the lymphoma progresses. 

What are the Causes of Canine Lymphoma?

The causes of canine lymphoma are listed below. 

• Genetics: The high incidence of lymphoma in purebred dogs such as Boxers, Basset Hounds, golden retrievers, and golden shepherds suggests that the condition has a genetic background. 
• Pollutants: Dogs living in houses close to three or more pollution sources are more likely to develop lymphoma, according to a study, “Environmental Exposures and Lymphoma Risk: A Nested Case-Control Study Using the Golden Retriever Lifetime Study Cohort,” Canine Medicine and Genetics in 2022. 
• Germs: Bacteria and viruses are theorized to answer the question of “what causes lymphoma in dogs?” 
• Magnetic Fields: Physical factors such as strong magnetic fields increase the risk of canine lymphoma. 

Can Autoimmune Disease Cause Lymphoma in Dogs?

No, autoimmune disease cannot cause lymphoma in dogs. Certain autoimmune conditions, however, appear to increase the risk of lymphoma. 

“Dogs with immune-mediated thrombocytopenia had a greater occurrence of lymphoma than dogs without immune-mediated thrombocytopenia” found a study “Immune-Mediated Disease as a Risk Factor for Canine Lymphoma,” published in Cancer in 1992. 

Autoimmune issues are found to increase the risk of lymphoma in humans. Certain types of lymphoma are more common in people with rheumatoid arthritis, for example. 

The exact role of autoimmune disease in the complex development of dog lymphoma is poorly understood. 

Does a Weak Immune System Raise the Risk of Lymphoma in Dogs?

Yes, a weak immune system raises the risk of lymphoma in dogs. The link is not proven in dogs but confirmed in people. 

Suppression of the immune system is a significant risk factor for human lymphoma. HIV-positive people receiving immunosuppressive drugs have a high incidence of lymphoma. 

A weakened immune system is believed to have the same effect on dogs because canine and human lymphoma share similar behaviors. 

What are the Symptoms of Canine Lymphoma?

The symptoms of canine lymphoma are listed below. 

• Enlarged Lymph Nodes: The earliest symptoms of canine lymphoma are firm, swollen, and non-painful lymph nodes. 
• Facial Swelling: Visible facial swelling develops in dogs with systemic and mediastinal types of lymphoma. 
• Skin Changes: Cutaneous canine lymphoma causes itchy, dry, and flaky skin followed by ulcers and irregularly distributed skin masses. 
• Stomach Upset: Vomiting and dark, foul-smelling diarrhea are common gastrointestinal lymphoma symptoms in dogs. 
• Difficulty Breathing: Trouble taking air paired with visible abdominal breathing is a symptom of mediastinal lymphoma. 
• Weight Loss: Loss of weight is a widespread side effect of cancer in dogs, including the different types of canine lymphoma. 
• Lethargy: Dogs with canine lymphoma become lethargic due to debilitating symptoms and general weakness. 

Can Canine Lymphoma Appear Suddenly?

Yes, canine lymphoma can appear suddenly. 

Dogs have more than 30 types of lymphoma, each unique in behavior. The most common type is high-grade, fast-progressing lymphoma, which reaches terminal stages within a month or two unless treated. 

Indolent lymphoma develops slowly and is minimally invasive, and it is rare.

When do Symptoms of Canine Lymphoma Typically Occur?

Symptoms of dog lymphoma typically occur when the cancer is at an intermediate or advanced stage. Treatment at the immediate or advanced stage is challenging. 

Pet owners must monitor their dogs for early lymphoma symptoms. The number one lymphoma sign is an enlargement of the lymph nodes. The lymph nodes of the neck, chest, armpits, knees, and groins are the easiest to check. 

What are the Risk Factors for Canine Lymphoma?

The risk factors for canine lymphoma are listed below. 

• Sex: Males are at a more significant risk of getting various lymphoma types compared to females.  
• Breed: Purebred dogs, especially particular breeds, such as Boxers and Golden Retrievers, are more susceptible to lymphoma than crossbreeds. 
• Neuter Status: Spayed females and neutered males are at increased risk of canine lymphoma compared to intact dogs. 

Is Canine Lymphoma Hereditary?

Yes, lymphoma is suspected to be hereditary. “Breed and overall genetics are the most studied causes for lymphoma development in dogs,” says an article, “How To Know If Your Dog Is At A High Risk For Lymphoma,” published by Imprimedicine in 2022. 

The exact cause of lymphoma in dogs is unknown. The cancer is believed to have a hereditary component because it is prevalent among certain breeds and lines. The inheritance mode is yet to be determined in detail. 

What are the Complications of Canine Lymphoma?

The complications of canine lymphoma are listed below. 

• Infections: The main role of lymphocytes is protection against infections. Lymphoma prevents lymphocytes from normal functioning, leading to an increased risk of infections.  
• Weakness: Cancer in dogs is debilitating, and dogs lose their appetite. Reduced appetite and low immune defenses in lymphoma dogs add to the weakness. 

Is Canine Lymphoma Contagious to Other Animals or Humans?

No, canine lymphoma is not contagious to other animals or humans. Certain endemic types of lymphoma in humans are transmissible, but canine lymphoma is not.

Precautions are recommended when living with a dog undergoing chemotherapy for lymphoma. Children and pregnant women must not handle feces, urine, or vomit from dogs receiving chemotherapy dogs. Household pets must not come into contact with the secretions.

How do Veterinarians Diagnose Canine Lymphoma?

Veterinarians diagnose lymphoma with a biopsy of an affected lymph node or organ. Biopsy is done under heavy sedation or general anesthesia, and after the procedure, the vet prescribes pain medications to keep the dog comfortable. 

The three methods for lymph node biopsy are Tru-cut needle biopsy, incision wedge biopsy, and excisional biopsy. 

Tru-cut needle biopsy is minimally invasive and requires local anesthesia. Incisional wedge biopsy uses a sharp blade to take a wedge-shaped sample. An excisional biopsy removes an entire lymph node. 

Where can You Seek a Diagnosis for Canine Lymphoma?

You can seek a diagnosis for canine lymphoma at the veterinarian’s office. The veterinarian examines the dog and takes a tissue sample for biopsy. 

The biopsy is done in-house or sent to a laboratory. The vet establishes the lymphoma stage to develop a treatment plan. 

Lymphoma staging is done based on bloodwork, urinalysis, chest X-rays, abdominal ultrasound and X-rays, and bone marrow aspirates.

How Long Can a Dog Survive with Canine Lymphoma?

A dog can survive with canine lymphoma for between one and 14 months. Dogs with untreated lymphoma die within one or two months of diagnosis. 

Dogs with various organs involved and dogs that do not respond to treatment live for a couple of months. 

The survival rate for dogs undergoing treatment for lymphoma and responding well is around 12 to 14 months. Complete remission with correct treatment is achieved in 80-90% of lymphoma dogs. 

What is the Prognosis for Dogs Diagnosed with Lymphoma?

The prognosis for dogs diagnosed with lymphoma is guarded. The time of diagnosis and the dog’s response to treatment determine the outcome. 

Dogs often go into remission, but lymphoma comes back. Achieving a second or third remission is possible, but each canine lymphoma remission is shorter than the last.  Cells become resistant to chemotherapy over time, so remissions after the first do not last for long. 

What are the Treatment Options for Canine Lymphoma?

The treatment options for canine lymphoma are listed below. 

• Chemotherapy: Chemotherapy is the cornerstone of treating canine lymphoma. Various protocols have been developed, but CHOP is the most commonly used one. CHOP consists of cyclophosphamide, doxorubicin (hydroxydaunorubicin), vincristine (oncovin), and prednisone. CHOP is cytotoxic chemotherapy, meaning it kills cancer cells and sometimes kills healthy cells. Chemotherapy is given to dogs orally or intravenously. 
• Surgery: Surgery is an option for dogs with single-site lymphomas, and is combined with chemotherapy for best results. 
• Radiation: Radiation in combination with surgery or chemotherapy is a treatment option for dogs with localized canine lymphoma. 

Can Early Detection Improve Treatment Outcomes for Canine Lymphoma?

Yes, early detection can improve treatment outcomes for canine lymphoma. Early detection of lymphoma allows prompt intervention. 

Canine lymphoma goes undetected until clinical signs become apparent. Signs develop when the condition is in an intermediate or advanced stage. Researchers work hard to develop an affordable blood test for early lymphoma detection. 

Is Chemotherapy the Most Common Treatment for Lymphoma in Dogs?

Yes, chemotherapy is the most common treatment for lymphoma in dogs. The golden protocol for canine lymphoma is called CHOP. 

CHOP consists of cyclophosphamide, doxorubicin (hydroxydaunorubicin), vincristine (oncovin), and prednisone. The treatment is a multiagent chemotherapy protocol combined with steroids. 

Dogs are much more tolerant to chemotherapy compared to people and rarely develop major side effects. 

Can CBD Oil Help Dogs with Lymphoma?

Yes, CBD oil can help dogs with lymphoma. Cannabidiol (CBD) is a natural hemp extract with health-boosting properties. 

“Cannabinoids have an anti-proliferative and apoptotic effect on canine lymphoma cells,” says a study “Anti-proliferative effect of cannabidiol (CBD) against B and T-cell lymphoma,” published in Cancer Research in 2020. 

CBD boosts the efficacy of chemotherapy and helps alleviate pain and inflammation. Talk to a vet to ensure the safe implementation of CBD oil to the dog’s lymphoma treatment strategy. 

Can Canine Lymphoma Be Cured?

No, canine lymphoma cannot be cured. Lymphoma, however, is manageable. Correct treatment helps dogs feel well for a timeframe without experiencing side effects. 

The period of feeling well and being asymptomatic while having cancer is called remission. Remission means the dog still has cancer but is at undetectable levels.