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 signs in lymphoma dogs.  

The standard supportive care option for dog lymph node cancer is chemotherapy. Chemotherapy is combined with radiation and surgery in some cases. 

Canine lymphoma is not curable. The goal is remission, which temporarily halts all cancer signs and can promote healthier long-term health.  

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 frequent, 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 factor. Lymphoma in dogs is fatal, but with support , many dogs go into remission . 

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 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.

• 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. 

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 cancer 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 issues, however, appear to increase the risk of lymphoma as shown in the research below. 

“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. 

What are the Signs of Canine Lymphoma?

The symptoms of canine lymphoma are listed below. 

• Enlarged Lymph Nodes: The earliest signs 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 sign 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 signs 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.. 

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

When do signs of Canine Lymphoma Typically Occur?

Signs of dog lymphoma typically occur when the cancer is at an intermediate or advanced stage. Supportive Care at the immediate or advanced stage is challenging. 

Pet owners must monitor their dogs for early lymphoma signs. 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. 

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 Support Canine Lymphoma?

Veterinarians support 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 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 Support for Canine Lymphoma?

You can seek support 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 plan. 

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

What are the Treatment Options for Canine Lymphoma?

The options for canine lymphoma are listed below. 

• Chemotherapy: Chemotherapy is the cornerstone of supporting 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 an option for dogs with localized canine lymphoma. 

Can Canine Lymphoma Be Cured?

No, canine lymphoma cannot be cured. Lymphoma, however, is manageable. Correct plans can support long-term health and assist in remission.  

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.