What to Know About Lymphoma in Dogs

corgi being examined at the vet

Dogs can develop illnesses and need medical treatment as they age just as we can. No one wants to think about their dog getting seriously sick or developing cancer, but knowing what to look for can help with early detection. Here’s what to know about lymphoma in dogs:

What is Lymphoma in Dogs?

Lymphoma is an umbrella term that describes a variety of cancers that stem from lymphocytes, which are a type of white blood cell found in the lymph nodes and throughout the lymphatic system. Lymphocytes play a vital role in assisting the immune system in fighting off infections in addition to moving fluids throughout the body.

Because of this, they are highly concentrated in organs that are highly active in the lymphatic system, including the kidneys, bone marrow, lymph nodes, and more. Although lymphoma can affect any organ in the body, it is most common in these organs and areas.

Lymphoma in dogs, which is also called canine lymphoma, is similar to non-Hodgkin’s lymphoma in people and tends to affect the body in the same way. Whether treating a human or a dog with lymphoma, the chemotherapy protocols are almost the same.

What Causes Lymphoma in Dogs?

In both humans and dogs, we still don’t know a lot about what specifically causes lymphoma. Although underlying genetic predispositions and causes are suspected, more genetic studies are required to establish this connection and identify specific markers or causes.

There are environmental factors and toxic substances that have been linked to cancer in humans. Since dogs share the same environment as we do, there is potential that any of these factors that affect humans also affect dogs similarly.

What Are the Symptoms of Lymphoma in Dogs?

Although more than 30 different types of lymphoma in dogs have been identified, most cases tend to fall into four main types. Because each one affects different areas, the early symptoms will vary.

It’s important to note that many of the symptoms overlap with other common illnesses that aren’t usually anything to worry about long-term. But, they are also symptoms you should never ignore in your dog, so you should still make sure you visit the vet as soon as possible.

4 Common Types of Canine Lymphoma & Their Symptoms

Here are the four most common types of canine lymphoma and the early symptoms that tend to present for each of them:

1. Alimentary Lymphoma

Alimentary lymphoma is the second most common type of lymphoma in dogs and accounts for less than 10% of canine lymphoma cases. It targets the intestines and causes gastrointestinal lesions. Abdominal pain, vomiting, diarrhea, appetite loss, and weight loss can all be symptoms of alimentary lymphoma.

2. Extranodal Lymphoma

While the other types of canine lymphoma are associated with a slightly more general area of the body, extranodal lymphoma is a type of lymphoma that targets a specific organ. This type of lymphoma in dogs is also rare.

When it occurs, the most common type of extranodal lymphoma is called cutaneous lymphoma and affects the skin. Other types of extranodal lymphomas include those that affect the central nervous system, eyes, lungs, or kidneys. Because this type of canine lymphoma is organ-specific, the symptoms will also tend to be specific to the affected organ.

Symptoms of Cutaneous Lymphoma

With cutaneous lymphoma, which targets the skin, you will often see scaly lesions that are more widely dispersed across the skin or individual, raised nodules. This type of lymphoma can occur anywhere on the skin, including the mouth. Should it appear here, these nodules or lesions can affect the roof of the mouth, the gums, and the lips.

Symptoms of Other Types of Extranodal Lymphoma

Respiratory distress is the most common symptom of extranodal lymphoma in the lungs while sight loss is common to lymphoma in the eyes. Should the lymphoma affect the bone marrow, bones often become brittle and fracture, which causes pain. Seizures are a common symptom of canine epilepsy and they can also be an early symptom of extranodal lymphoma targeting the central nervous system.

3. Mediastinal Lymphoma

Mediastinal lymphoma affects lymph nodes in the chest area and is caused by high-grade malignant T lymphocytes in the thymus and/or mediastinal lymph nodes. This type of lymphoma in dogs is rare.

Because mediastinal lymphoma can cause fluid to accumulate or a swollen mass to form in the chest, dogs with this type of canine lymphoma will have difficulty breathing. They will often have shortness of breath and be coughing. They may also experience increased thirst, which is often paired with frequent urination. Their face and front legs may also swell.

4. Multicentric Lymphoma

Multicentric lymphoma accounts for around 80-85% of canine lymphoma cases, which makes it the most common type of lymphoma in dogs. This type specifically targets and affects the lymph nodes.

The most common symptom of multicentric lymphoma is the rapid enlargement of the lymph nodes that can be 3-10 times their normal size. This makes swollen lymph nodes one of the first symptoms of multicentric lymphoma, especially in the lymph nodes in the neck, armpits, behind the knees, chest, and groin as these are the easiest to feel when they are enlarged.

Although these swollen lymph nodes will feel like firm, rubbery lumps, they should move freely beneath the skin and not be painful. Accompanying symptoms can include fever, weakness, dehydration, weight loss, loss of appetite, and lethargy.

How Do You Treat Lymphoma in Dogs?

If your dog is diagnosed with lymphoma, chemotherapy is the most effective treatment. The type of chemotherapy will vary depending on the type of lymphoma. The vet may also recommend surgery or radiation therapy if it is a low-grade localized type. However, most cases of lymphoma in dogs require chemotherapy.

Dogs going through chemotherapy may experience some side effects, but they do not generally get as severe as side effects can be in humans and some dogs may not experience them at all. If they experience side effects, the most common include mild diarrhea, mild vomiting, a decrease in activity levels, and a decrease in appetite.

Hair loss is common in humans, but is uncommon in dogs. Although it is rare in dogs overall, hair loss can occur in certain breeds. Poodles, Bichon Frise, Old English Sheepdogs, and more are breeds where hair loss has been a documented side effect of chemotherapy treatment.

The prognosis for lymphoma varies greatly depending on the type, progression, aggressiveness, treatment used, etc. There may be some unknowns, but your vet will be able to give you guidance, outline what to expect, and help you navigate this situation as best as possible.

These are the basics of lymphoma in dogs. Because the symptoms for so many things overlap, especially early symptoms, you don’t want to automatically assume the worst, but you should still make sure you visit your vet to rule out more serious conditions and get your dog the treatment they need to feel better.

Regular vet visits in addition to paying attention to changes in your dog’s appetite, behavior, etc. are essential to your dog’s overall health and make a big difference when it comes to early detection.