When Should You Worry About Lymphoma in Dogs?

You are likely aware that lymphoma is a form of cancer that impacts both humans and dogs. Hearing that your dog received its first canine lymphoma diagnosis, could be particularly concerning and troublesome. However, there are more than 30 types of canine lymphomas, each of them impacting your pet differently.

When it comes to dogs, hearing a “lymphoma” diagnosis should not cause immediate concern. Certain types of lymphoma should generate significant interest, while there are others with which you don’t need to concern yourself. Below, we’ve provided a breakdown of lymphoma in dogs, hopefully clarifying when you should be the most worried.


What is Lymphoma in Dogs?

Canine lymphoma and non-Hodgkin’s lymphoma are quite similar, the primary difference being that the former effects dogs while the latter effects people. As mentioned, there are more than 30 types of canine lymphoma. Lymphoma is a broad term that refers to any group of cancers impacting the lymphocytes.

lymphoma in dogs

Lymphocytes are white blood cells meant to aid the immune system. In both dogs and humans, they exist in organs that aid with the fight against infections. Technically, because white blood cells exist throughout the entire body, lymphoma can occur anywhere. Typically, however, doctors and veterinarians tend to find them in:

  •  The lymph nodes
  • Bone marrow
  • The spleen

Unfortunately, researchers are unaware of what causes lymphoma in dogs. Over the past few years, they have focused more of their efforts on finding the cause. Recently, their studies have keyed in on advanced genetic studies, as they believe that there are genetic and chromosomal factors that predispose some dogs to the condition.


Types of Canine Lymphoma

Canine lymphoma makes up anywhere from 7 to 14 percent of the diagnosed cancers found in dogs. Although there are 30 different types of canine lymphoma, there are four that are more common than the rest. They are multicentric lymphoma, alimentary lymphoma, extranodal lymphoma, and mediastinal lymphoma. These are the four about which you’ll most want to learn.



Multicentric Lymphoma

lymphoma in dogs

Although the four types of lymphoma listed above are the most commonly seen in dogs, veterinarians see multicentric lymphoma most frequently. Some studies say that as much as 80 percent of the lymphomas seen in dogs are of the multicentric variety. This lymphoma affects the lymph nodes directly, often enlarging them to the point that they become noticeable.

Swollen lymph nodes are often the first symptoms that your dog will show. The lymph nodes will be noticeably more massive, with the potential to swell to ten times their usual size. Your dog will likely not find these painful, and you can touch them without issue. They should feel like a solid fat mass. As time progresses, your dog may exhibit other symptoms like loss of appetite, dehydration, fever, and lethargy.


Alimentary Lymphoma

dog

Of the 30 canine lymphomas, alimentary lymphoma is the second-most common. Vets report that approximately ten percent of dogs suffering from lymphoma have the alimentary form. Alimentary lymphoma often targets the intestines, and symptoms will reflect as such. Because the intestines are internal, owners should be on the lookout for other types of warning signs, such as:

  • Tenderness in the abdominal area
  •  Loss of appetite
  • Vomiting
  • Diarrhea
  • Weight Loss



Extranodal Lymphoma

black dog

This type of lymphoma refers to any lymphoma attacking a specific organ. It is a broad term that encompasses various other types of lymphoma. Typically, extranodal lymphoma will impact a dog’s skin, although it could affect organs such as the kidneys, eyes, lungs, and central nervous system. Sometimes, it can be difficult for veterinarians to determine where extranodal lymphoma began.


Symptoms of extranodal lymphoma can vary drastically depending on which organ is affected. If the lymphoma impacts your dog’s skin, you may notice lesions that are dry or scaly. If the lymphoma is in your dog’s mouth, you may see sores on its lips or bums. If the lymphoma were to affect other organs, the symptoms could be more severe.


For instance, if extranodal lymphoma makes it’s way to your dog’s lungs, then you may begin seeing signs of a respiratory infection. If the disease were to make its way to your dog’s kidneys, they’d likely suffer from renal failure. Furthermore, your dog will probably go blind if lymphoma impacts their eyes, while lymphoma of the bones could make them frailer and prone to fractures.


Mediastinal Lymphoma

lymphoma in dogs

Although it is one of the four most common canine lymphomas, mediastinal lymphoma is relatively rare. This type of cancer impacts the mediastinal or thymus lymph nodes. If severe enough, both could be affected. When a dog has mediastinal lymphoma, high-grade malignant T lymphocytes enlarge. It could be more difficult visibly locate mediastinal lymphoma than it is to pinpoint multicentric lymphoma.



Diagnosing Lymphoma

If you notice a large mass, or your dog displaying other bizarre symptoms, you should not panic. Even if your dog does have lymphoma, it may not be fatal. Before panicking, you should call your pet’s veterinarian and inform them of what’s causing your concern. Your vet will likely advise you to come in so that they can further evaluate your pet’s condition.

lymphoma in dogs

If your vet suspects that your dog is suffering from lymphoma, they will likely draw a sample of the organ they believe is affected. They typically do so through a fine-needle aspiration, which allows them to take a histopathologic tissue exam or cytology exam. This exam will only work if the vet draws a tissue sample from the correct organ.

Additionally, this test will only confirm or deny whether your dog has lymphoma. If you wish to determine how far along the lymphoma is, and thus how much you need to worry, your vet may recommend a staging test. Your vet will conduct a staging test only after they’ve confirmed a definite lymphoma diagnosis. The staging test allows them to see how far cancer has spread and includes:

  • Blood tests
  • X-Rays
  • Bone Marrow Aspirations
  • Abdominal Sonograms
  • Urinalysis

Deciding to Treat Lymphoma in Dogs

After your vet has confirmed lymphoma and determined how advanced it is, they will likely advise you on their recommended course of action. Typically, your vet will either encourage you to treat the lymphoma, to not address the lymphoma and allow it to run its course, or to ignore the lymphoma because it does not threaten your dog’s quality of life.

This is the point where you can begin worrying about lymphoma in dogs, as your veterinarian will likely give you a candid outlook on how the disease will impact your dog’s life. Chemotherapy in dogs can be useful, but it’s a costly and grueling process. After careful discussions with your vet, you should have a better idea if it’s the correct course of action at that particular point in time.

dog checkup

Your vet may also recommend various forms of surgery or radiation therapy to help treat the cancerous cells. Fortunately, if your dog requires chemotherapy, the process is less invasive than it is for humans. For instance, dogs often keep their hair when undergoing chemotherapy, and the process does notmake them as sick as it does people. It will likely cause diarrhea, vomiting, anorexia, and lethargy.

However, you may also determine that it’s not in your or your pet’s best interest to undergo chemotherapy. For instance, take this person’s story, where he decided that the cost of the surgery was not worth, considering that their dog would likely face death a few months down the road and that chemotherapy was merely kicking the proverbial can down the road.

In summary, you should not worry about lymphoma in dogs until your veterinarian has given you a grim diagnosis. First and foremost, some of the symptoms that you may see in your dog, such as lethargy or a loss of appetite, may not necessarily occur because of lymphoma. There are a wide array of diseases that could cause these issues, and you should not immediately assume the worst.

Secondly, even if a vet diagnoses your dog with lymphoma, it may not mean the end is near. With more than 30 different types of lymphoma that could affect dogs, there’s no need to panic until you’ve received the proper diagnosis from your vet. It’s entirely possible that your dog has a non-fatal form of lymphoma and that they can continue living a high-quality life without treatment. It’s only after your vet has given a fatal diagnosis that you can begin to worry. Each situation is different, however. For instance, your vet may tell you treatment is not necessary and that the lymphoma is spreading slowly. Or, they could inform you that treatment should prove useful and that it can extend your dog’s life by a couple of years.

The times when you should most worry are when your vet informs you the cancer is moving quickly and that they cannot guarantee that chemotherapy will work. This is when you’ll have to make a tough decision, as you must decide whether the chemo if worth the cost. If you decide that it’s not, you must choose whether your dog will live their last few months with painful lymphoma.

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Dr Roger Johnson

Roger K. Johnson, DVM, Diplomate ACVIM (internal medicine) is a board- certified veterinary internal medicine specialist. His professional interests include cardiology as well as using advanced diagnostics to help his patients. His particular favorites include echocardiography, abdominal ultrasonography, and endoscopy.

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