Lymphoma in Dogs: Symptoms, Diagnosis, and Treatment

by Richard Walther, DVM
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Lymphoma in Dogs: Symptoms, Diagnosis, and Treatment
Lymphoma is considered one of the most common cancers in dogs. Read on to find out more about the symptoms, treatment options, and prognosis.

Lymphoma is a type of cancer in dogs. If your pet has lymphoma, the prognosis will depend on which type they have, where it is, how far it has spread, and how aggressive it is. In this article, we’re discussing the most common symptoms of canine lymphoma, diagnosis, treatment options, survival rates, and more.

We'll cover everything you need to know about lymphoma in dogs throughout the sections below.

Table of Contents

Pro tip: Many pet insurance plans cover different types of cancer, including dogs with lymphoma. By enrolling in pet health insurance, you can give your dog the best treatment to preserve their quality of life should the worst happen.

What is Lymphoma?

Lymphoma (also known as lymphosarcoma) is one of the most common kinds of cancer in dogs, accounting for 7% to 24% of all canine cancers. It develops from lymphocytes, cells of the immune system that circulate through the blood and tissues. For this reason, lymphoma is considered a systemic disease with more than thirty known variations, rather than a singular type of cancer.

Lymphosarcoma can originate in any organ but it usually starts in some part of the immune system, like the lymph nodes, liver, bone marrow, and spleen. In more than 50% of the dogs with lymphoma, the disease is present in the lymph nodes. Less commonly, it occurs in the intestines, skin, chest cavity, and other organs.

Senior and middle-aged pups are more likely to develop lymphoma. Nearly 50% of dogs over age 10 will develop cancer, but some genetically predisposed breeds are at a higher risk. The list includes:

  • Basset Hounds
  • Boxers
  • Bull Mastiffs
  • Airedale Terriers
  • Bull Terriers
  • Golden Retrievers
  • Saint Bernards
  • Scottish Terriers

Canine lymphoma, one of the most researched and best-understood types of canine cancer, is very similar to human non-Hodgkin’s lymphoma. Due to this similarity, human doctors and vets use almost the same treatment protocols.

Unfortunately, canine lymphoma cannot be cured but it is one of the few dog cancers that can have long periods of remission. With adequate treatment, many pets can enjoy a normal quality of life for some time following diagnosis.

Woman holding dog near window (Image source:[Pexels]((Image source: Pexels)

Causes of Lymphoma in Dogs

The cause of lymphoma in dogs is not known. Scientists suspect that the cause might be multifactorial, as dogs share our environment. This means that they’re exposed to the same cancer-causing factors, including toxic substances like pesticides, insecticides, herbicides paints, solvents; exposure to electromagnetic fields or radiation; the influence of bacteria, viruses, and immunosuppression.

Forms of Lymphoma in Dogs

There are over 30 known types of canine lymphomas, all of which vary in symptoms, aggressiveness, and survival rates. Here are the most common types of canine lymphoma that dog owners should be aware of:

Multicentric Lymphoma

Multicentric cancer is the most common type of canine lymphoma, accounting for up to 85% of all cases. It primarily affects the lymph nodes, and swollen lymph nodes are usually the first clinical symptom. If your dog displays swelling, don't panic immediately, as it could also be in response to inflammation or infection. However, you should schedule an appointment with your veterinarian to discuss your concerns as soon as possible.

Alimentary Lymphoma

Alimentary lymphoma is the second most common form of lymphoma in dogs, accounting for less than 10% of akk cases. This form of the disease targets the intestines, causing gastrointestinal lesions which result in diarrhea, vomiting, and weight loss.

Miscellaneous Extranodal Lymphoma

This cancer targets a specific organ in the body, such as the central nervous system, lungs, skin, kidneys, and eyes. One of the most common types of extranodal lymphoma is cutaneous lymphoma, which affects the skin.

Mediastinal Lymphoma

Mediastinal lymphoma is a rare form of the disease. It usually causes the thymus or mediastinal lymph nodes in the chest to become enlarged.

Symptoms of Lymphoma in Dogs

The clinical signs will vary depending on the type of canine lymphoma and the organ(s) it affects. However, the most common symptoms of dogs with lymphoma include:

  • Swollen lymph glands
  • Loss of appetite
  • Lethargy
  • Extreme thirst
  • Drastic weight loss

In canines with multicentric lymphoma, the most obvious symptom are enlarged lymph nodes. The swellings feel like firm lumps that move freely under the skin and are not painful. Pets with this type of lymphoma might also develop fever, lethargy, weakness, dehydration, and anorexia.

Animals with alimentary lymphoma might experience vomiting, diarrhea, weight loss, abdominal pain, and anorexia.

The symptoms of extranodal lymphoma will depend on which organ is affected. The most common type, cutaneous lymphoma, primarily involves the skin and can appear in a variety of lesions. The lesions can be plaques, ulcers, reddish patches, areas of hair loss and scaling, and lumps. Noticeable lesions can also appear in the lips, gums, or roof of your pup’s mouth, which may be itchy. If your dog develops this type of canine lymphoma, you might also notice raised nodules.

When the cancer affects other parts of the body, extradonal lymphoma symptoms in dogs might appear involve:

  • Lungs - respiratory distress
  • Central nervous system - seizures
  • Kidneys - renal failure
  • Eyes - blindness
  • Bones - fractures and chronic pain

The clinical signs of canine mediastinal lymphoma include excessive thirst, increased urination, and swelling in the face or legs due to elevated calcium levels in the blood. Most commonly, dogs experience difficulty breathing due to excess fluid building up in the chest cavity (known as pleural effusion), or the lymphoma itself compressing the lungs.

Diagnosis of Lymphoma in Dogs

Veterinarians usually diagnose canine lymphoma with a biopsy, or the extraction of a sample cancer cell for microscopic analysis. They might order bloodwork and additional lab tests,** such as a urinalysis, to check if the organs are functioning properly.

Some vets also recommend “staging tests” to determine how far the lymphoma has progressed throughout the body. These tests help vets understand the animal’s overall condition and identify potential health issues that might affect the cancer treatment and prognosis. Staging tests can include x-rays of the abdomen and chest, abdominal sonograms, as well as bone marrow aspiration.

The staging of lymphoma is very complicated, but in general, it follows something similar to the outline below:

There are five stages of canine lymphoma:

  • Stage l: A single lymph node is affected.

  • Stage ll: Multiple lymph nodes are affected, but only on one side of the diaphragm.

  • Stage lll: Multiple lymph nodes are affected on both sides of the diaphragm.

  • Stage lV: The spleen and/or liver become affected.

  • Stage V: The bone marrow, central nervous system, or other extranodal sites become affected.

Stages lll-V are more common, whereas we rarely catch and diagnose dogs in stages I and II.

Treating Lymphoma in Dogs

If your dog is diagnosed with lymphoma, they may need to see a veterinary oncologist. The oncologist will recommend suitable treatment based on the cancer’s stage and aggressiveness. The most commonly used treatment is chemotherapy but in some cases, a combination of treatments may be recommended.

Chemotherapy

Chemotherapeutic drugs are usually given by IV (intravenous) injection in order to destroy cancer cells and stop them from multiplying. Some chemotherapy treatments may also be given orally, in the form of tablets and capsules.

Most dogs tolerate chemotherapy well, but about 20% of them will experience some of the side effects that humans experience, including vomiting, nausea, diarrhea, decreased activity, and loss of appetite. Unlike humans, dogs usually don’t experience hair loss when treated with chemotherapy. The exceptions to this rule are Old English Sheepdogs, Poodles, and some Terrier breeds. Hair growth usually resumes once chemotherapy is discontinued.

Even though some pets do get sick from chemotherapy, more serious side effects are not common. If more severe side effects occur, talk to your oncology doctor or staff. They will recommend symptomatic treatment to ease these side effects or decide to reduce the dose next time chemotherapy is given.

In some cases, dogs can enter remission following chemotherapy. However, most pups suffering from this disease will have a relapse sooner or later. A second remission can be achieved in a large number of canine patients, but it is usually shorter in duration than the first one. This is due to the fact that the lymphoma cells become more resistant to the effects of chemotherapy over time.

Radiation Therapy

Radiation therapy uses high-energy gamma rays to destroy cancer cells in the area affected by lymphoma. This type of therapy is painless, but the dog might experience skin irritation in the targeted area after treatment. In that case, an antipruritic may be prescribed, or the dog might be given a cone to wear to prevent them from scratching.

Surgery

If the cancer is still localized, affected lymph nodes or other tumors might be surgically removed.

Cost of Cancer Treatment for Dogs

The cost of canine lymphoma treatment can be quite high, possibly more than $10,000, especially if owners choose to explore all available treatment options. The diagnosis and treatment expenses will depend on several factors, including geographic location, the standard of care, and whether specialty hospitals are employed.

  • Typically, diagnosing a dog with cancer costs about $500 but this can increase significantly if thorough investigation is required.
  • The cost of chemotherapy for canine lymphoma will vary depending on the dog’s size and the selected protocol.
  • On average, radiation therapy costs between $5,000 and $10,000 with some experimental approaches reaching up to $15,000.
  • The cost of the surgery ranges from $1,000 to $3,000 depending on the location of the tumor and the surgeon’s degree of specialization.

Pro tip: When people wonder whether pet insurance is worth the cost, expenses like these demonstrate its value. Plans covers illnesses such as cancer, as well as the medication required to maintain good quality of life. However, you won't be able to receive pet insurance for pre-existing conditions, so it's important to enroll your dog early, prior to the development of health issues later in life.

Dog paw with IV

(Image source:Pexels)

Canine Lymphoma Prognosis

The prognosis will depend on the type of lymphoma your dog has, the cancer stage at the time of treatment, and the selected treatment.

In general, the more places the wider the lymphoma has spread, the poorer the prognosis. However, pets with very advanced lymphoma can still be treated and experience remission.

Pets in remission usually still have cancer but it has become undetectable to any available screening test. Treatment can extend your pet’s life, but it rarely cures the disease completely and most lymphoma patients will have a relapse sooner or later.

Dealing With Canine Lymphoma

Unfortunately, lymphoma is almost always fatal. However, there are certain steps pet parents can take to help their dogs after diagnosis. Your veterinarian will explain the available treatment options and what to expect as the disease progresses.

If your pet has many uncomfortable symptoms associated with lymphoma, such as vomiting, diarrhea, and lack of energy, and if the cancer has also become painful, you might want to consider euthanasia. Euthanasia is a peaceful and painless way to end your loved one's suffering. The process is similar to general anesthesia and takes no more than a few minutes. Your veterinarian can help you decide when the time is right to euthanize your dog.

If you decide not to put your dog to sleep, your vet will explain how to make your dog’s final days or weeks more comfortable with the proper use of pain medications, dietary choices, and human interaction.


Key Takeaways

  • Lymphoma is a type of cancer in dogs and humans that commonly develops in the immune system.
  • The symptoms of dogs with lymphoma can vary depending on the type of cancer, the organ affected, and the stage of its aggression. Typically, the first signs include enlarged lymph nodes and excessive urination due to increased thirst.
  • Treatment options are available to extend the life of a dog with lymphoma, but unfortunately, the disease is eventually fatal.
  • Pet insurance can help you cover vet costs if your loved one becomes sick so you can maximize their quality of life.
  • If you are worried that your dog might have lymphoma, or you need more information about the disease, contact your veterinarian.

Ricky Walther, DVM

About the author

Richard Walther, DVM

Associate Veterinarian - Blue Ravine Animal Hospital

Ricky Walther, DVM, is a small animal general practitioner at Blue Ravine Animal Hospital in the greater Sacramento, California area. Realizing the positive financial and medical impact that pet insurance can provide for pet parents and the profession, he lends support and advice to companies like Pawlicy Advisor that simplify the process of connecting with veterinary financing resources.

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