Lymphoma, also known as lymphosarcoma, is a malignant disease of the lymphoid organs. This accounts for ~25% of all canine cancer cases, making it the 3rd most common cancer in dogs.
The lymphatic system is responsible for the following functions:
• Absorption of fatty acids
• Maintenance of body fluid levels
• Production of immune cells to fight infection and prevent diseases
Thus, without a properly functioning lymphatic system, your dog will experience lethargy and a weakened immune system.
In this article, we discuss the different types and stages of lymphoma, signs and symptoms to look out for and the treatment methods available.
We’d like to thank the following veterinarians for their insightful contributions for this topic:
*Disclaimer: The information in this article is not meant to replace the advice and expertise of vets. You should consult a vet on your dog’s health condition for an accurate diagnosis.
Main Types of Lymphoma in Dogs
These are the 4 main types of lymphoma in dogs, and their corresponding signs and symptoms.
It’s important to note that lymphoma can affect almost any part of the body, so the signs and symptoms will depend on the organ affected.
Also, Dr. Shadi Ireifej pointed out that some dogs with lymphoma may be symptom-free.
Multicentric LymphomaSigns and symptoms
• Visibly swollen lymph nodes
• Weight loss
Multicentric lymphoma refers to cancer cells affecting the lymph nodes throughout the body.
For many dogs, the first sign of lymphoma is an enlarged lymph node, which you can feel by petting your dog or giving them a bath.
The lymph nodes are located on their rear legs behind their knees, under their armpits, and under their jaw against their neck.
According to Dr. Mason Butler, 80% of canine lymphoma is multicentric, making it the most common type.
Within this 80%, 75% of the cases are attributed to B-cell lymphoma which affects the lymph nodes and hematopoietic organs.
Alimentary LymphomaSigns and symptoms
• Loss of appetite
• Swollen belly
Alimentary lymphoma causes gastrointestinal lesions, which affects the digestive tract. This is the 2nd most common type of lymphoma in dogs (10%).
Mediastinal LymphomaSigns and symptoms
• Difficulty breathing
• Swelling of face and front legs
• Increased thirst
Mediastinal lymphoma causes lesions in a dog’s chest, which take up space in the chest cavity. This is considered as a rather rare form of lymphoma.
Extranodal LymphomaSigns and symptoms
• Skin: Scaly wounds on skin
• Eye: Loss in vision
• Bones: Joint pain, fractures
• Central nervous system: seizures
(Depends on organ affected)
Extranodal lymphoma affects a specific organ outside of the lymphatic system. Some examples include the eyes, kidney and lungs.
The most common type of extranodal lymphoma is cutaneous lymphoma, which affects the skin.
Dog Breeds Prone To Lymphoma
Dogs that are middle-aged or older are more prone to this disease.
As for dog breeds, the following may be more susceptible:
• Golden Retriever
• Basset Hound
• Saint Bernard
Dog breeds that are at a lower risk include Dachshunds and Pomeranians.
Causes of Lymphoma in Dogs
Dr. Butler mentioned that in most cases, the cause of lymphoma is not clear. However, these are some of the possible causes.
It’s important to note that more causes are being discovered as research is ongoing.
According to Dr. Ireifej, Golden Retrievers are found to have more chromosomal gains and losses as compared to other breeds.
This translates to a 2.8 times increase in risk of developing B-cell and T-cell lymphoma.
Other causes could be environmental factors such as
• Inhalation of tobacco smoke
• Inhalation or ingestion of paint
• Exposure to radiation and electromagnetic field
How to Diagnose Lymphoma
Fine needle aspiration
What is it and how is it done?
A sample of the affected lymph node is taken using a thin needle. This is usually done while the patient is awake and under mild sedation as it causes mild discomfort.
In cases when a biopsy needs to be done, the patient will be under general anesthetic as it involves removing a larger sample of tissue.
What is it for?
After the sample collection, the veterinarian will examine the cells under a microscope.
X-rays and ultrasound scans
What is it and how is it done?
The patient will have to stand against the X-ray or ultrasound machine for a few seconds while the scan is done.
As these procedures will require the patient to be still, mild sedation is usually needed.
What is it for?
According to Dr. Suzee Camilleri, these scans will be able to detect the location(s) of enlarged lymph nodes accurately and determine if the lymphoma has spread.
Stages of Lymphoma in Dogs
Canine lymphoma is categorised by 5 stages and 2 substages for each stage. This is an indication of how serious the condition is.Stage 1: Involvement of one lymph node or lymphoid tissue in a single organ only
Stage 2: Involvement of numerous lymph nodes (either in the front or back of body)
Stage 3: Enlargement of lymph nodes in both the front and back of body
Stage 4: Involvement of the liver and/or spleen
Stage 5: Involvement of blood, central nervous system or other organs
For each of the 5 stages, there are 2 substages:
Substage A: Patient doesn’t exhibit any symptoms and is generally healthy
Substage B: Patient exhibits symptoms of feeling unwell
Generally, patients categorised under Substage A are more likely to go into remission after treatment.
Treatment for Canine Lymphoma
According to Dr. Rebecca Greenstein, lymphoma is treatable. However, dog parents should not confuse that to mean that it can be cured.
Here are some of the ways that canine lymphoma may be treated to improve your pet’s health.
The gold standard for lymphoma treatment is the CHOP protocol, which is chemotherapy with the use of 4 drugs. This combination therapy is done over the course of 25 weeks.
Lymphoma cannot be cured; therefore, chemotherapy is used to alleviate the effects of the cancer to improve the patient’s quality of life.
Dr. Butler provided the following statistics:
80% of B-cell lymphoma patients: complete remission
Median survival period: 12 months
20% of patients: survive for 2 years
Radiation therapy uses high-energy rays to eliminate cancer cells. This is effective for treating lymphoma as this disease is highly radiosensitive.How effective is it?
Dr. Ireifej provided the following statistics:
Survival time: 4 – 55 months
Stage 1 patients treated with chemotherapy and radiation therapy for 6 months: survive for 2.5 years
Helping Your Dog Cope With Lymphoma
If you notice any symptoms or changes in your dog’s energy level or appetite, it’s best to consult a veterinarian to get any necessary treatments as soon as possible.
Keeping your pet’s spirits up while spending more time with him would improve his state of mind.
Pet parents should also consider getting a suitable insurance policy for their pets before the onset of such diseases.