Lymphoma: When Your Dog or Cat's Immune System Goes Awry


Our furry friends have plenty of natural tools available to keep them healthy. Lymphoid tissue can be found throughout your pet’s body and is made up of lymphocytes, white blood cells that work to protect the body from disease.

Sometimes, however, the very system meant to protect our pets can go awry. Due to changes in the body not entirely understood, Lymphocytes can become destructive and reproduce uncontrollably. When that happens, lymphosarcoma (lymphoma)—a cancer of the lymphocytes—can develop.

Unfortunately, the exact cause for the disease is unknown. While no breed of cat is known to have a higher risk of lymphoma than other breeds, those infected with feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) are at increased risk of developing lymphoma.

As for our canine friends, Boxers, Golden Retrievers, and Bassett Hounds are all at higher risk for the disease.

Because lymphoid tissue is found throughout your pet’s body, lymphoma can emerge in many different locations, including the lymph nodes, liver, spleen, gastrointestinal tract, and skin. The disease, once diagnosed, is classified according to the location in the body in which the cancer begins.

General symptoms include lumps and bumps, which indicate enlarged lymph nodes. These can appear as swellings in the neck behind the jaw, behind the knees, in front of the shoulder blades, and elsewhere.

General symptoms of the disease include lethargy, loss of appetite, and weight loss. In addition, certain signs can be indicative of certain types of lymphoma:

  • Chest – Coughing and difficulty breathing
  • Gastrointestinal tract – Signs of vomiting, diarrhea, and blood in the stool
  • Spinal cord – Impaired movement
  • Kidneys – Increased drinking and urinating
  • Skin – Raised growths

If lymphoma is suspected, your veterinarian will likely recommend the following blood work:

  • A complete blood count to evaluate the red, white blood cells and platelets
  • Chemistry tests to evaluate kidney, liver, and pancreatic function, and sugar levels
  • Electrolyte tests to ensure your pet isn’t dehydrated or suffering from an electrolyte imbalance
  • Urinalysis to rule out urinary tract infection and other disease
  • Feline leukemia virus and feline immunodeficiency virus (FeLV/FIV) tests in cats as these viruses can lead to lymphoma.
  • In dogs - screening for vector-borne disease

The most common way to diagnose lymphoma is to take a sample of the affected tissue. Methods include:

  • Needle aspiration
  • Biopsy of affected tissue
  • An x-ray or ultrasound of the chest and abdomen may also help your veterinarian identify affected regions of the body. When diagnosed, lymphoma is classified by stage according to severity, from Stage I-V.

It is very important to pursue treatment because the average life expectancy of a pet with untreated lymphoma is not long. Methods of treatment include:

  • Chemotherapy for general treatment
  • Radiation therapy (in some cases may be combined with chemotherapy)
  • Your veterinarian may refer you and your pet to a veterinary oncologist for the latest in effective treatment. Treatment rarely cures lymphoma, but most pets tolerate chemotherapy very well and enjoy a good quality of life after the cancer goes into remission. It is not unusual for remission to last for 12 months or longer, but this is ultimately dependent on the stage of cancer and other factors, such as age.

The cause of lymphoma is unknown, so there is no known method of prevention. To help reduce the severity of the disease and increase the length and quality of life for your pet, it is important to focus on early detection, treatment, and management of the disease.

If you have any questions or concerns, you should always visit or call your veterinarian – they are your best resource to ensure the health and well-being of your pets.

Lymphoma In Dogs: An Extensive Guide

Lymphoma is one of the critical diseases that is profound in dogs. After hearing this, you must be wondering what the disease is? Well, it is nothing but common cancer that can be much terrifying for dogs and the owners. Basically, this affects the lymphoid system. Aslo, the major cause of this disease is due to the disturbance of the white blood cells called lymphocytes and specifically refers to the diverse group of cancers in dogs. In order to protect the body from any

infectious viruses and bacteria, the lymphocytes act as a part of the immune system to protect the body.

However, through this article, we are going to describe you the entire description about the probable symptoms, types, causes, and also the available treatment process.

So properly read the article and save your dog’s life by the methods mentioned here.

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Canine lymphomas are a diverse group of cancers, and are among the most common cancers diagnosed in dogs. They collectively represent approximately 7-14% of all cancers diagnosed in dogs. There are over 30 described types of canine lymphoma, and these cancers vary tremendously in their behavior. Some progress rapidly and are acutely life-threatening without treatment, while others progress very slowly and are managed as chronic, indolent diseases. Lymphomas may affect any organ in the body, but most commonly originate in lymph nodes, before spreading to other organs such as the spleen, liver, and bone marrow.

Canine lymphomas are similar in many ways to the non-Hodgkin's lymphomas (NHL) which occur in humans. Canine lymphomas and NHL are nearly indistinguishable when examined microscopically, and both tumor types exhibit similar responses to chemotherapy. In 2010, NHL was diagnosed in approximately 65,000 people in the United States, and claimed approximately 20,000 lives, making it the 7th-most common cancer overall, and the 6th-most common cause of cancer-related death. It is one of the few human cancers for which the frequency of newly diagnosed cases is still on the rise. It is our hope that research in canine lymphomas conducted by the Purdue Comparative Oncology Program will discover new ways of treating NHL in both dogs and humans. Our goal is to improve the outlook for dogs and humans affected with this all-too-common cancer.

Frequently Asked Questions by Pet Owners

What is lymphoma?

The term “lymphoma” describes a diverse group of cancers in dogs that are derived from white blood cells called lymphocytes. Lymphocytes normally function as part of the immune system to protect the body from infection. Although lymphoma can affect virtually any organ in the body, it most commonly arises in organs that function as part of the immune system such as the lymph nodes, spleen, and bone marrow. By far the most common type of lymphoma in the dog is multicentric lymphoma, in which the cancer first becomes apparent in lymph nodes. The photo to the right shows a dog with multicentric lymphoma. Note the swollen mandibular lymph node (white arrow) under the jaw.

Other common lymphomas in dogs include cutaneous lymphoma (lymphoma of the skin), alimentary or gastrointestinal lymphoma (lymphoma of the stomach and/or intestines) and mediastinal lymphoma (lymphoma involving organs within the chest, such as lymph nodes or the thymus gland).

What causes lymphoma in dogs?

Unfortunately, the cause of lymphoma in dogs is not known. Although several possible causes such as viruses, bacteria, chemical exposure, and physical factors such as strong magnetic fields have been investigated, the cause of this cancer remains obscure. Suppression of the immune system is a known risk factor for the development of lymphoma in humans. Evidence for this includes increased rates of lymphoma in humans infected with the HIV virus or are on immune-suppressing drugs following organ transplantation surgery. However, the link between immune suppression and lymphoma in dogs is not clearly established.

What are the most common symptoms of canine lymphoma?

The most common initial symptom of multicentric lymphoma in dogs is firm, enlarged, non-painful lymph nodes. A lymph node affected by lymphoma will feel like a hard, rubbery lump under your dog’s skin. The most easily located lymph nodes on a dog’s body are the mandibular lymph nodes (under the jaw) and the popliteal lymph nodes (behind the knee). Other common symptoms include loss of appetite, lethargy, weight loss, swelling of the face or legs (edema), and occasionally increased thirst and urination. The photo on the left shows a dog with edema of the left rear leg. This is caused when a swollen lymph node blocks the normal drainage of fluid from the leg.

Cutaneous lymphoma tends to appear first as dry, flaky, red, and itchy patches of skin anywhere on the body. As the disease progresses, the skin becomes moist, ulcerated, very red, and thickened. Masses in the skin can also occur with cutaneous lymphoma. Cutaneous lymphoma may progress slowly and often has been treated for several months as an infection or allergy before a diagnosis of lymphoma is made. Cutaneous lymphoma may also appear in the mouth, often affecting the gums, lips, and the roof of the mouth. Cutaneous lymphoma in the mouth is often mistaken for periodontal disease or gingivitis in its early stages. The photo on the left shows cutaneous lymphoma in the mouth of a dog. Note the very red gums and the ulceration on the roof of the mouth.

Dogs with gastrointestinal lymphoma usually have symptoms such as vomiting, watery diarrhea, and weight loss. The diarrhea is often very dark in color and foulsmelling.

Dogs with mediastinal lymphoma typically have difficulty breathing. This may be due to the presence of a large mass within the chest or due to the accumulation of fluid within the chest (pleural effusion). Affected dogs may also show swelling of the face or front legs as well as increased thirst and urination.

How is canine lymphoma diagnosed?

The best way to diagnose lymphoma is to perform a biopsy. A biopsy is a minor surgical procedure to remove a piece of lymph node or other organ affected by cancer. The most common methods for lymph node biopsy are Tru-cut needle biopsy, incisional wedge biopsy, or removal of an entire lymph node (excisional biopsy). The larger the biopsy sample, the better the chance for an accurate diagnosis of lymphoma.

We routine perform biopsy procedures to diagnose canine lymphoma at the Purdue University Veterinary Hospital. Dogs are placed under heavy sedation or general anesthesia to perform a biopsy. Although discomfort associated with this procedure is typically minimal, we often prescribe oral pain medication afterwards just to be sure your dog is comfortable following the biopsy.

Are any other diagnostic tests required for dogs with lymphoma?

In addition to biopsy, we recommend several staging tests for dogs with lymphoma. The purpose of the staging tests is to determine how far the lymphoma has spread throughout your dog’s body. In general, the more places the lymphoma has spread to, the poorer the dog’s prognosis. However, dogs with very advanced lymphoma can still be treated and experience cancer remission (see more on treatment below). Staging tests also help us assess whether your dog has any other conditions that may affect treatment decisions or overall prognosis. The staging tests we typically recommend include blood tests, a urinalysis, x-rays of the chest and abdomen, an abdominal sonogram, and a bone marrow aspirate. Organs that appear abnormal on sonogram can be sampled with a small needle (fine needle aspirate) to confirm the presence of lymphoma.

How is canine lymphoma treated?

The most effective therapy for most types of canine lymphoma is chemotherapy. In some cases, surgery or radiation therapy may also be recommended. There are numerous chemotherapy treatment protocols for dogs with multicentric lymphoma. As discussed below, most dogs with lymphoma experience remission of their cancer following treatment, and side effects are usually not severe. Currently, the protocols that achieve the highest rates of remission and longest overall survival times involve combinations of drugs given over several weeks to months. The protocol we use as a “gold standard” for the treatment of canine multicentric lymphoma is a 25-week protocol called UW-25. It is based on a protocol called CHOP that is commonly used to treat lymphoma in humans.

The UW-25 protocol may not be appropriate for all dogs with lymphoma. Different types of lymphoma may be treated with different chemotherapy drugs. For instance, the most effective drug for cutaneous lymphoma is thought to be lomustine (CCNU). The veterinary oncologists and oncology residents at the PUVTH will help you decide on a chemotherapy treatment protocol that is appropriate for your dog.

What does remission mean?

"Remission" means a regression of your dog’s cancer. Remission may be partial, meaning the overall cancer burden has been reduced by at least 50%, or it may be complete, meaning the cancer has become undetectable to any readily available screening test. In general, 70-90% of dogs with multicentric lymphoma treated with UW-25 experience complete or partial remission of their lymphoma, with most dogs experiencing complete remission.

How is chemotherapy given at Purdue?

Most chemotherapy drugs are given by intravenous (IV) injection, although a few are given by mouth as a tablet or capsule. Typically, an IV catheter will be placed in one of your dog’s veins to allow us to administer chemotherapy safely. A small patch of hair will be shaved over your dog’s leg where the catheter is placed.

Chemotherapy appointments with the PUVTH oncology service are on weekdays, Monday - Thursday. Patients are usually dropped off at 9:00 AM and are ready to go home by 12:00-1:00 PM.

Will chemotherapy make my dog sick?

Most dogs tolerate chemotherapy well, much better than humans typically do. Although some dogs do get sick from chemotherapy, serious side effects are uncommon. In general, fewer than 5% of dogs treated for lymphoma using chemotherapy will experience side effects that need to be managed in a hospital setting. The most common side effects include loss of appetite, decreased activity level, and mild vomiting or diarrhea that persists for one or two days. If serious or unacceptable side effects do occur, it is important that you talk to one of our oncology doctors or staff about this. We can recommend symptomatic treatment to lessen the side effects of chemotherapy. In addition we may recommend reducing the dose of chemotherapy the next time it is to be given.

Unlike people, dogs usually do not lose their hair when treated with chemotherapy. The exceptions to this rule are poodles, Old English sheepdogs, and some terriers – these breeds may lose their hair while receiving chemotherapy. Hair growth should resume once chemotherapy is discontinued.

Will chemotherapy cure my dog’s lymphoma?

In rare instances, dogs are apparently cured of their lymphoma by chemotherapy. Unfortunately, most dogs with lymphoma will have relapse of their cancer at some point. A second remission can be achieved in a large number of dogs, but it is usually of shorter duration than the first remission. This is because the lymphoma cells become more resistant to the effects of chemotherapy as time goes on. Eventually, most lymphomas develop resistance to all chemotherapy drugs, and dogs with lymphoma die or are euthanized when the cancer can no longer be controlled with chemotherapy.

What is the prognosis for dogs with lymphoma?

Your dog’s prognosis is determined by what type of lymphoma he or she has and what type of chemotherapy is used to treat the lymphoma. The median length of survival of dogs with multicentric lymphoma treated with UW-25 chemotherapy is between 9-13 months. (The term “median” implies that 50% of dogs will survive beyond this time point and 50% of treated dogs will die before this time point.) Various other factors, such the type of lymphoma your dog has or its stage of disease, may affect your dog’s overall prognosis. The oncologists and oncology residents at the PUVTH will discuss your dog’s prognosis in detail with you before any treatment decisions are made.

Are there any studies at Purdue involving canine lymphoma?

Yes! We are currently conducting multiple clinical trials for dogs with lymphoma at Purdue. Varying degrees of financial support are available to owners who agree to allow their dogs participate in these clinical trials. To determine whether your dog may qualify for a clinical trial, please ask your dog's primary care veterinarian to call 765-494-1107 and ask to speak with a member of our Canine Lymphoma clinical trials team, or you may contact our Canine Lymphoma Clinical Trials Coordinator, Ms.Sarah Lahrman at 765-496-6289.

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Treating Feline Lymphoma

The treatments given to humans for cancer, such as chemotherapy, are also given to cats with lymphoma. However, in the case of chemotherapy, it is given to cats, not to achieve a cure, but to extend the cat's life as long as possible, while maintaining as high a quality of life as possible.   It is a matter of balance, and often the dosages or the combinations of chemotherapy may change as needed, to attain that end goal while minimizing side effects. Alternative treatments, depending on the type and location of the tumors, are surgery or radiation.

For dogs that already have breathing or lung issues, inhaling tobacco smoke can worsen their symptoms and chronic coughing. 22

Dogs can develop changes in their airways and lungs that are similar to those found in people who smoke. Ultra-fine smoke particles can activate the immune system of people. A type of white blood cell in the lungs involved in this immune response is called an alveolar macrophage. 23 Alveolar macrophages watch what comes into the lungs, and if they detect something abnormal, they phagocytize, or “eat,” it to get rid of it.

Alveolar macrophages, special kind of cells normally found in the lungs, are the lungs’ front line against infections. They recognize invading bacteria, fungi, or viruses and send out help signals to other cells in the immune system telling them to join the fight. 24 Alveolar macrophages also act as mini-housekeepers because they get rid of dead or dying tissue and other harmful things, like particles of tobacco smoke, dust, or plant pollen. 25 When harmful things get into the lungs, more alveolar macrophages are recruited to roam around, look for, find, and get rid of them. People who smoke, therefore, have an increased number of alveolar macrophages because their bodies are trying to get rid of all the tobacco smoke particles in their lungs. Dogs exposed to tobacco smoke also have an increased number of alveolar macrophages—some of which contain black smoke particles—likely for the same reason. 26

How tobacco smoke affects a dog depends on the length of the dog’s nose. Why? Because noses are big air filters. Have you ever dusted a dirty room and then had to blow your nose? Chances are you had black-looking yuck on your tissue afterward. The hair and mucus in your nose and the mucus in your sinuses act like glue traps. They trap particles like dust, pollen, and tobacco smoke, and keep them out of your lungs. Bigger noses, therefore, will trap more particles. This holds true, especially in dogs.

Long-nosed dog breeds like Greyhounds, Borzois, and Doberman Pinschers that are exposed to tobacco smoke have a doubled risk of nose cancer. 27 Their noses filter out a lot of inhaled tobacco smoke particles, which stay trapped in their noses so less get into their lungs. Unfortunately, this puts the tissues inside the nose and sinuses in contact with a lot of toxic, cancer-causing particles, leading to the increased risk of nose cancer.

Short- and Medium-nosed breeds, like Pugs, Bulldogs, Beagles, and Brittany Spaniels, have a higher risk of lung cancer. Why? Because their noses are much shorter, fewer tobacco smoke particles get filtered out and more go directly into the lungs. 28 Those ultra-fine particles like to go deep into the lungs, leading to the increased risk of lung cancer.

Watch the video: FeLV and FIV - conference recording (July 2021).