Extranodal Lymphoma in Dogs: A Comprehensive Guide to the Disease

Extranodal lymphoma in dogs is a type of cancer that affects the lymphatic system outside of the lymph nodes. It can occur in various parts of the body, including the skin, gastrointestinal tract, and central nervous system.

Extranodal lymphoma is the most common type of lymphoma in dogs, accounting for about 70% of all lymphoma cases. The disease can be classified into several subtypes, each with distinct characteristics and treatment options.

The exact cause of extranodal lymphoma in dogs is not fully understood, but it is believed to result from a combination of genetic and environmental factors, including exposure to certain viruses and chemicals.

The causes of extranodal lymphoma in dogs are still not fully understood, but research suggests that they may be multifactorial, involving exposure to cancer-causing factors in the environment.

Dogs with impaired immune function are at increased risk for lymphoma, which is why it's essential to keep them up-to-date on their vaccinations and preventatives.

Dogs with immune-mediated diseases are also at increased risk, independent of age and sex, making regular check-ups with your veterinarian crucial.

A case report has shown that cyclosporine treatment can increase the risk of lymphoma in dogs.

Infectious factors such as retroviral or Helicobacter infection may be involved, although the evidence is not yet definitive.

Environmental factors, including herbicides like 2,4-D, have been linked to an increased risk of lymphoma in dogs.

Some dog breeds, such as Golden Retrievers, Labradors, Basset Hounds, Saint Bernards, and Boxers, may be more susceptible to lymphoma due to their genetic predisposition.

Here's a list of some dog breeds that may be more prone to lymphoma:

There are over 30 known types of canine lymphomas, all of which vary in symptoms, aggressiveness, and survival rates.

The most common form of lymphoma in dogs is the multicentric form, which commonly involves the peripheral nodes but may also include liver, spleen, and bone marrow.

Classification of lymphoma is based on several factors, including anatomic location, staging, histologic criteria, and immunophenotype.

The World Health Organization’s Clinical Staging System for Lymphoma helps veterinarians diagnose and treat the disease by assigning a stage based on the extent of the disease.

Here is a breakdown of the stages:

Extranodal forms of lymphoma, such as CNS, ocular, nasal, cardiac, lung, bladder, and bone, are also a significant concern for dog owners.

Symptoms of extranodal lymphoma in dogs can vary depending on the organ affected, but common symptoms include lesions on the skin, which can appear as plaques, ulcers, reddish patches, areas of hair loss and scaling, and lumps. These lesions can also appear in the lips, gums, or roof of the mouth, which may be itchy.

The symptoms of extranodal lymphoma can also depend on the organ affected, and may include respiratory distress if the lungs are involved, seizures if the central nervous system is involved, renal failure if the kidneys are involved, blindness if the eyes are involved, and fractures and chronic pain if the bones are involved.

A unique perspective: What Are the First Signs of Lymphoma in Dogs

Here are some specific symptoms that may be associated with extranodal lymphoma in dogs, depending on the affected organ:

A definitive diagnosis of extranodal lymphoma in dogs is typically made through a combination of physical examination, cytology/histopathology, and laboratory tests, such as a complete blood count and serum biochemistry profile.

Symptoms of lymphoma in dogs can vary depending on the type of cancer and the organs it affects. Swollen lymph glands are a common symptom, especially in dogs with multicentric lymphoma.

The most obvious symptom of multicentric lymphoma is enlarged lymph nodes, which feel like firm lumps under the skin and are not painful. Dogs with this type of lymphoma might also develop fever, lethargy, weakness, dehydration, and loss of appetite.

Dogs with alimentary lymphoma may experience vomiting, diarrhea, weight loss, abdominal pain, and loss of appetite. These symptoms can be distressing for both the dog and its owner.

A unique perspective: Multicentric Lymphoma in Dogs

The symptoms of extranodal lymphoma will depend on which organ is affected. For example, if the skin is affected, dogs may develop lesions that can appear as plaques, ulcers, reddish patches, areas of hair loss and scaling, and lumps.

Here are some common symptoms of extranodal lymphoma in different parts of the body:

Dogs with mediastinal lymphoma may experience excessive thirst, increased urination, and swelling in the face or legs due to elevated calcium levels in the blood. They may also have difficulty breathing due to excess fluid building up in the chest cavity or the lymphoma compressing the lungs.

Clinical signs of lymphoma can be nonspecific, such as mild lethargy or weight loss, or they can represent the organ system that is infiltrated. Dogs that are clinically ill may have profound inappetence, lethargy, weight loss, vomiting, and/or diarrhea.

Some common clinical signs related to the anatomic location of the disease include uveitis, cranial abdominal enlargement, dyspnea, and regional lymph edema. Dogs with lymphoma may also experience dermal or subcutaneous masses, vomiting or diarrhea, bruising, pallor, stridor, and stertor if retropharyngeal nodes are involved.

For your interest: What Food Gives Dogs Diarrhea

So you're trying to figure out what's going on with your symptoms, and you're wondering what could be causing them. One of the first steps in diagnosis is to consider all the possible causes, which is called differential diagnosis.

Reactive lymphoid hyperplasia is one possibility, which can cause swelling in the lymph nodes. It's a pretty common condition that can be triggered by a variety of factors.

Systemic infection is another potential cause, which can affect the entire body and cause symptoms like fever and fatigue. I've seen people with systemic infections who are really struggling to get better.

Bacterial infections, such as Rickettsial disease, can also be a cause of symptoms. These infections can be caused by a variety of bacteria and can be serious if left untreated.

Fungal and parasitic infections can also cause symptoms, and can be tricky to diagnose. These types of infections can be caused by a variety of fungi and parasites, and can affect different parts of the body.

Explore further: Dog Body Language with Other Dogs

Viral infections are another possibility, and can cause symptoms like fever and fatigue. Some viral infections can be really contagious, so it's a good idea to take precautions if you think you might have one.

Immune-mediated disease is a final possibility, which occurs when the immune system starts attacking healthy tissues. This can cause a wide range of symptoms, and can be really challenging to treat.

Here are some potential causes of symptoms to consider:

Fine needle aspiration is a common diagnostic tool used by veterinarians to examine affected lymph nodes. It's usually done while the patient is awake and under mild sedation, and causes only mild discomfort.

A thin needle is used to collect a sample of the lymph node, which is then examined under a microscope. This procedure is often used in conjunction with other diagnostic tests to determine the presence and type of lymphoma.

The veterinarian will typically examine the cells under a microscope to determine if they are cancerous. This process can help identify the type of lymphoma and inform treatment decisions.

In some cases, a biopsy may be necessary, which involves removing a larger sample of tissue under general anesthesia. Fine needle aspiration is a quick and relatively painless procedure that can provide valuable information about a dog's lymphoma diagnosis.

If your dog is diagnosed with extranodal lymphoma, they may need to see a veterinary oncologist who will recommend suitable treatment based on the cancer's stage and aggressiveness.

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

Chemotherapy is a commonly used treatment for canine lymphoma, and most dogs tolerate it well, but about 20% may experience some side effects like vomiting, nausea, diarrhea, decreased activity, and loss of appetite.

If your dog is diagnosed with lymphoma, they may need to see a veterinary oncologist.

Chemotherapy is the most commonly used treatment for lymphoma in dogs, but in some cases, a combination of treatments may be recommended.

Some dogs may experience side effects from chemotherapy, such as vomiting, nausea, diarrhea, decreased activity, and loss of appetite.

However, most dogs tolerate chemotherapy well, and severe side effects are not common.

In some cases, dogs can enter remission following chemotherapy, but most will have a relapse sooner or later.

A second remission can be achieved in a large number of canine patients, but it's usually shorter in duration than the first one.

Unfortunately, lymphoma is almost always fatal, and euthanasia may be considered if your pet is experiencing uncomfortable symptoms and pain.

Cancer treatment costs can be a significant concern for pet owners. Diagnosing a dog with cancer can cost around $500, but this can increase significantly if thorough investigation is required.

The cost of chemotherapy for canine lymphoma varies 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.

Surgery costs range from $1,000 to $3,000, depending on the location of the tumor and the surgeon's degree of specialization. This highlights the importance of considering pet insurance to help cover these expenses.

Here's a breakdown of the estimated costs for different treatment options:

Pet insurance can help cover these costs, but it's essential to enroll your dog early, prior to the development of health issues later in life.

The prognosis for canine lymphoma varies depending on several factors, including the type of lymphoma, cancer stage, and chosen treatment.

Pets with lymphoma that has spread to multiple places generally have a poorer prognosis.

However, even with advanced lymphoma, treatment can still be effective and lead to remission, making life extendable for your pet.

Remission means the cancer is no longer detectable, but it doesn't necessarily mean it's cured, and most pets will experience a relapse.

Treatment can be tailored to your pet's specific needs and circumstances, and your veterinarian will explain the available options and what to expect.

If your pet is experiencing severe symptoms, such as vomiting, diarrhea, and lack of energy, and the cancer is causing pain, euthanasia may be a compassionate option to consider.

The process is similar to general anesthesia and takes only a few minutes.

Your veterinarian can help you decide when the time is right to euthanize your dog.

Here are some key prognostic factors to consider: