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Pet Health

How to Identify a Dog Cancer Lump

Dog cancer affects dogs as it does humans. Learn about signs, symptoms, and common types of dog cancer, such as lymphoma and osteosarcoma. Early detection is key.

Dr. Karen Whala

April 26, 2024

Understanding Dog Cancer

At CodaPet, we understand the profound bond between pets and their families. One of the most challenging situations for pet owners, as with any family member, is dealing with the realization that your pet may have cancer. Cancer is a group of diseases characterized by uncontrolled growth and spread of abnormal cells. Unfortunately, it affects dogs just as it does humans. There are several types of cancer that can affect dogs, including skin, bone, and internal organ cancers. Each type of cancer has its own set of symptoms, progression rates, and treatment options. It's crucial to understand the signs and symptoms of dog cancer to ensure early detection and effective treatment.

Common Types of Dog Cancer

There are several types of cancer that commonly affect our canine companions, each with unique implications for their health and well-being:


This is the most common form of cancer in dogs and cats and affects the lymphatic system. It is typically noticed by swellings of the lymph nodes located in the neck, shoulders and behind the knee in the early stages. As it progresses, it can include the liver, spleen and GI tract. Rarely, a form of lymphoma called Lymphoma Fungoides affects the skin first and can mimic other types of skin disease. As in people, a cause has not been clearly identified.


Large and giant breeds are particularly susceptible to this aggressive bone cancer. It has a unique propensity for 3 specific areas of the body which, among veterinarians, has popularly resulted in the phrase “Away from the elbow and towards the knee”. Early symptoms include intermittent limping and/or swelling in the wrist or knee. This is believed to be very painful as it progresses and thus many vets will recommend amputation to reduce pain as there are few effective treatment options. Unfortunately, by the time pets are diagnosed (x-rays), about 80% have already microscopically metastasized to the lungs. Typically your vet will ask to take an x-ray of both the affected limb and lungs as part of diagnostic plan.

Mast Cell Tumors

Commonly developing within the skin, these tumors can also metastasize to internal organs. Some breeds are particularly prone to this condition with Boxers being most common. This cancer can mimic ‘benign fatty tumors’ in appearance and thus all fat-like masses should be investigated by your veterinarian as you cannot distinguish by palpation alone. These tumors can classically result in changing sizes from day-to-day. This is because they are made up of histamine-producing cells and when aggravated, can swell up with fluid like in an allergic reaction. The exact causes are varied, with genetic factors playing a significant role. The most common and effective treatment, once diagnosed, is surgical resection to prevent spread.

Understanding the type of cancer is crucial for treatment and prognosis. At CodaPet, we stand ready to support you with compassionate advice tailored to your dog's specific condition.

Importance of Regular Check-ups

Regular veterinary check-ups are essential for maintaining your furry friend's health and can be particularly pivotal in the early detection and treatment of diseases such as cancer. During a standard check-up, your veterinarian will conduct a thorough physical examination, searching for any unusual signs like lumps or abnormal growths that could indicate the presence of a tumor. In addition to a hands-on examination, your vet may also perform a series of diagnostic tests, including blood work and urinalysis, to get a complete picture of your dog's health status.

Scheduling these check-ups should be a routine part of your dog's healthcare regimen. For dogs in the prime of their health, annual check-ups are advisable. However, as dogs age or if they have pre-existing conditions, more frequent visits, ideally every six months, become crucial to monitor their well-being closely. Detecting cancer early can significantly increase the success of treatment, giving your pet the best chance at a longer, healthier life.

Identifying a Cancer Lump in Dogs

Discovering a lump on your beloved dog can be a source of immediate concern. It is essential to recognize the possible indications of a cancerous lump, which vary in appearance. These lumps may feel firm or pliable and could show changes in size over time. The color of the lump can also differ, having no standard hue to indicate malignancy. Importantly, cancerous growths can emerge on any part of your dog’s body, underscoring the need for thorough, regular check-ups.

Distinguishing between a cancerous lump and a benign one like lipomas, which are typically harmless fat deposits, or cysts is vital – yet not always straightforward. Benign lumps often remain consistent in size and texture, whereas malignant ones might grow or evolve unpredictably.

A palpable lump on your dog should never be overlooked or presumed benign without veterinary insight. Changes in a lump's size, shape, or texture, particularly if rapid, necessitate immediate professional evaluation.

Characteristics of Dog Cancer Lumps

Shape and Size of Cancer Lumps

The shape and size of a lump can offer important insights into whether it could be indicative of cancer. While benign tumors are often round and smooth, cancerous lumps may present in a variety of shapes, displaying irregular borders and surface changes. These features may suggest a more aggressive nature of the lump, necessitating prompt veterinary attention.

A characteristic to be concerned about is the rate at which a lump changes. Cancerous growths often increase in size or undergo changes in shape at a noticeably faster pace than benign ones. Also noteworthy is that cancerous lumps can be situated in deeper tissue layers, making them less apparent to the eye but possibly more easily felt when petting or grooming your dog.

It's essential for pet owners to be vigilant about monitoring their pets for any new growths or alterations in existing lumps. By tracking these changes and maintaining open communication with your veterinarian, you can better assess the urgency and nature of the lump. At CodaPet, we are committed to guiding you through this process with empathy and expertise, helping you discern what symptoms may be of concern and offering the resources needed to address them sensitively and knowledgeably.

Color and Texture of Cancer Lumps

The appearance of lumps on your pet can be concerning. When assessing canine cancer lumps, the color and texture are notable markers. Typically, a lump with cancerous potential may show a variation in color of the skin, sometimes presenting as darker than the surrounding skin. Its important to check carefully. Sometimes a cancerous is under the skin and thus hidden by a pets hair. The texture can vary significantly – from firm and fixed to the underlying tissues, which may suggest something more sinister, to soft and mobile, which may be less alarming but still warrants attention.

Location of Cancer Lumps

Cancerous lumps can appear anywhere on a dog's body, but there are certain areas where they are more commonly found. These include the skin, lymph nodes and mammary glands. It's important to check all areas of your dog's body regularly for lumps, including those that might not be immediately visible. The location of a lump can also influence the treatment options available, with some areas being more challenging to treat than others. At CodaPet, we can provide guidance and resources to help you understand what to look for and what to expect if your dog is diagnosed with cancer.

Rate of Growth of Cancer Lumps

The rate of growth in cancer lumps is a vital piece of diagnostic information. Benign tumors tend to exhibit slow growth patterns and may remain static in size over extended periods. In contrast, malignant growths can demonstrate more aggressive expansion. That said, the speed at which cancerous lumps grow can differ dramatically, influenced by cancer's type and the individual dog's health and circumstances.

Observing and tracking the progression of any lump on your dog is crucial. Noticing a remarkable increase in size over a short span could be indicative of malignancy. Should such growth be observed, an immediate veterinary consultation is advised. At CodaPet, we understand the seriousness of these symptoms and offer support as you navigate your pet’s health concerns. Our resources and compassionate guidance are designed to help you during these potentially difficult times.

Difference Between Harmless Lumps and Cancerous Lumps

Understanding Harmless Lumps

Not all lumps are a sign of serious illness; in fact, many are simply harmless growths that may cause little to no discomfort to your pet. Understanding what harmless lumps are can provide peace of mind and inform your approach to your pet's care. Harmless lumps, often referred to as benign tumors, include a variety of growths such as lipomas—fatty tumors that are typically soft, movable, and painless. These growths can appear anywhere on the body and are particularly common in older dogs.

Cysts are another example, frequently arising from blocked oil glands or hair follicles. Sebaceous cysts, specifically, are filled with oils, fluid or skin debris and are generally noncancerous. However, since some lumps may change over time, it is crucial to monitor them. Skin tags are also common benign skin growths that may hang off the skin and are generally of no medical concern.

Differentiating harmless lumps from ones that could be cancerous involves noting characteristics like size, texture, growth rate, and whether the lump is fixed in place or movable. Cancerous lumps may be more irregular in shape, hard, and anchored to the underlying tissue.

While these descriptions may offer a foundation, it's vital to consult with a veterinarian for an accurate diagnosis.

Identifying Characteristics of Cancerous Lumps

Cancerous lumps possess distinctive features that set them apart from non-cancerous growths. Often, these lumps may grow rapidly or irregularly, changing in size more noticeably than benign growths. The surface may become rough or uneven, and the coloring could look different from surrounding skin or tissue. On palpation, cancerous lumps tend to be firmer and may be anchored to underlying tissues, making them less likely to move under the skin than benign lumps, which are generally soft and mobile.

Another alarming sign is the presence of a discharge or bleeding from the lump, which is not a common attribute of harmless growths. Recognizing these characteristics is crucial; however, they are not definitive for a diagnosis of cancer. Due to the nuanced nature of these symptoms, a veterinarian's evaluation is essential for an accurate assessment. At CodaPet, we emphasize the importance of obtaining expert advice and support, ensuring that any concerns about lumps are professionally addressed with the utmost care and consideration for your pet's well-being.

Common Misconceptions About Lumps

There are numerous misunderstandings surrounding lumps on pets that can lead well-meaning owners astray. It's a prevailing myth that a lump is less concerning if it appears painless or doesn't seem to bother the animal. However, the presence or absence of pain doesn't necessarily correlate with the nature of a lump. In fact, some very serious conditions may manifest as lumps that initially cause little to no discomfort. Similarly, there's a fallacy that cancerous lumps are consistently hard and fixed in place. This is misleading, as some malignant growths may be soft or even movable. The texture and mobility of a lump are not definitive indicators of whether it's cancerous.

It's critical for pet owners to understand that these common misconceptions should not guide their decisions. Only a qualified veterinarian can accurately assess a lump's characteristics and its implications for your pet's health. At CodaPet, we emphasize the importance of professional evaluation and are poised to offer compassionate support and information as you navigate your pet's diagnosis and possible treatment paths.

Physical Examination of Your Dog At Home

How to Properly Examine Your Dog

Regular at-home examinations are an important part of your dog's healthcare routine. To properly examine your dog for lumps, start by running your hands over their entire body, applying gentle pressure to feel for any unusual bumps or swellings. Be sure to check all areas of your dog's body, including under the armpits, on the belly, and in the mouth. If you find a lump, it's important not to panic. Take note of where you found the lump and its size, and then schedule an appointment with a vet for a professional evaluation.

Areas to Pay Close Attention to

While lumps can appear anywhere on a dog's body, there are certain areas that you should pay close attention to during your at-home examinations. These areas include the skin, especially in areas with less fur; the mammary glands in female dogs; and the lymph nodes, which are located in various parts of the body including the armpits, groin, and neck. To check these areas, use your fingers to gently feel for any lumps or swellings. Remember, early detection is key when it comes to treating cancer and other health issues. At CodaPet, we're here to provide the guidance and resources you need to conduct thorough at-home check-ups.

What to Look for During the Examination

When conducting a physical examination of your dog at home, it's vital to be observant of any new lumps or bumps or changes in existing ones. Pay particular attention to:

  • The size of any lumps – noting if they appear to be growing.
  • The color and texture – any alterations in these could be significant.
  • Any associated discomfort or signs of pain this could manifest as your dog limping or exhibiting behavior changes.

Beyond the physical characteristics of lumps, you should be watchful for systemic symptoms such as:

  • Unexpected weight loss.
  • Decreased appetite.
  • General lethargy or decreased energy levels.

These signs might suggest that a lump could be more than just a benign growth. Always keep in mind that while these signs can indicate cancer, they might also be indicative of other health issues. That's why if you detect any such changes, it's imperative to seek veterinary expertise. Contacting a professional will help ensure an accurate diagnosis and the best course of action for your furry friend's health. At CodaPet, we're dedicated to supporting you through these concerns, helping you to safeguard the happiness and health of your pet.

What to Do If a Lump is Found

If you discover a lump on your pet during a routine check-up at home, it's pivotal to approach the situation with a sense of composed vigilance. Immediately document the lump's details, noting its precise location, size, texture, and if it has recently changed in any manner. The initial action should be to arrange a veterinary consultation for a thorough evaluation. At the vet's office, anticipate a comprehensive physical examination. Your vet may suggest diagnostic tests such as a fine-needle aspiration, biopsy, or imaging like an ultrasound to ascertain the characteristics of the lump. At CodaPet, we understand the worry that accompanies the discovery of a lump on a beloved pet. Rest assured, we’re here to offer compassion, to guide you with the pertinent resources and unfaltering support during these times.

Common Tests Performed by Vets

When you discover a lump on your beloved pet, understanding what it means for their health is paramount. Veterinarians use a series of tests to diagnose lumps, including:

  • Physical Examination: The vet thoroughly palpates the lump to assess its size, texture, and mobility. They also examine the surrounding tissue and lymph nodes for any abnormalities.
  • Blood Tests: Comprehensive blood panels are used to evaluate your pet’s general health, organ function, and can sometimes hint at the presence of certain cancers.
  • Fine-Needle Aspiration (FNA): A small, thin needle is inserted into the lump to extract cells for examination under a microscope. This test can differentiate between types of cells and often identify cancerous ones.
  • Biopsy: A more invasive, but highly informative test where a piece of the lump’s tissue is surgically removed and analyzed to arrive at a definitive diagnosis.
  • Imaging Tests: X-rays, ultrasounds, and sometimes advanced imaging like CT scans or MRIs provide a visual perspective of the lump and can reveal the extent of its growth or spread.

These tests are necessary not just for diagnosis but also for crafting a carefully tailored treatment plan. At CodaPet, we're here to walk you through these procedures with understanding and support, ensuring you and your pet face this challenge with clarity and confidence.

Understanding the Testing Process

Understanding the testing process for cancer lumps is an essential step in preparing both you and your pet for what lies ahead. When you bring your pet into the vet for an examination of a lump, here's what you can generally expect:

  • Physical Examination: The vet will start with a thorough physical examination, where they will palpate the lump, observing its size, shape, texture, and whether it appears to be fixed or mobile.
  • Biopsy or Aspiration: Depending on the initial assessment, your vet may recommend a biopsy or a fine-needle aspiration. These procedures are important to obtain a definitive diagnosis.
  • Fine-needle Aspiration: This minimally invasive procedure is typically done without sedation. The vet will use a needle to extract cells from the lump for cytology.
  • Biopsy: This is a more invasive process and your dog may need to be sedated or anesthetized. It involves the removal of a small piece of tissue from the lump for histopathological examination in the lab.
  • Laboratory Analysis: The gathered samples are sent to a veterinary pathologist who will analyze the cells or tissue. This step is critical to determine the nature of the lump—whether it's benign or cancerous.
  • Waiting for Results: The timeframe from initial testing to obtaining the results can vary. It generally takes several days to a week or more, based on the complexity of the tests and the workload of the laboratory.
  • Preparing Your Pet: Prior to testing, ensure your pet is calm and comfortable. If a biopsy is planned and anesthesia is required, your vet will guide you on the pre-test fasting or any other necessary preparation.

At CodaPet, we understand the anxiety that comes with waiting for a diagnosis. Rest assured that our compassionate team is here to offer guidance and emotional support. We're committed to providing you with resources and the care needed during this uncertain time, so you can focus on what's most important: being there for your pet.

Interpreting the Test Results

After conducting veterinary tests for potential cancer lumps on your beloved pet, the ensuing step is to comprehend what the results convey. This can be an overwhelming moment, but your veterinarian will play a key role in breaking down the findings clearly. When the results are in, they could reveal that the lump is benign, meaning it is noncancerous and may not require further treatment. However, if it presents an issue due to its size or location, causing discomfort or impacting your pet's quality of life, your vet might suggest its removal.

In the case that the lump is determined to be cancerous, your vet will collaborate with you to explore the various treatment pathways available. Options could range from surgery to remove the lump to more intensive methods like radiation therapy or chemotherapy. The recommended course of action will heavily depend on a few critical factors: the type and stage of the cancer, your pet's age, and their overall health.

Next Steps After a Positive Result

Upon receiving a positive result, which indicates that the lump on your pet is cancerous, it’s natural to feel a sense of fear or uncertainty. However, it's important to know that, depending on the type and stage, many forms of canine cancer can be managed or treated with today's veterinary advancements. The available treatment avenues can vary greatly and may include surgical procedures to excise the tumor, radiation therapy targeting cancerous cells, or chemotherapy intended to halt the proliferation of these cells. Each option is selected based on the cancer's location, type, and progression, as well as your pet’s overall health and well-being.

Equally significant is the implementation of diligent follow-up care. Consistent vet check-ups and attentiveness to your dog's condition are fundamental for monitoring the treatment's effectiveness and promptly addressing any complications or recurrences.

Treatment Options for Dog Cancer

Surgical Treatment for Dog Cancer

Surgical treatment may be recommended if the cancer is localized and hasn't spread to other parts of the body. The procedure involves removing the tumor, as well as some of the surrounding healthy tissue to ensure all cancer cells are removed. While surgery can be an effective treatment for many types of dog cancer, it's not without risks, including the risks associated with anesthesia, infection, and complications during recovery. However, many dogs recover well from surgery and go on to live healthy lives. A

Radiation Therapy for Dog Cancer

Radiation therapy employs high-energy beams, such as X-rays or electron beams, to target and destroy cancer cells. It is often an option for treating localized tumors that have not spread or as an adjunct to other modalities like surgery or chemotherapy. The aim is to deliver a high dose of radiation to the tumor cells while minimizing damage to the surrounding healthy tissue.

Benefits of radiation therapy may include shrinking the tumor, improving your pet's quality of life, or even potentially curing the cancer. Vets typically recommend radiation for certain types of cancer, including but not limited to, bone tumors, brain tumors, and nasal cavity tumors, especially if surgical removal is challenging or impossible.

However, radiation therapy is not free of side effects, and your pet's well-being remains our utmost concern at CodaPet. Possible adverse reactions include skin irritation, resembling a sunburn, hair loss in the treatment area, and general fatigue. In some cases, more severe side effects might occur, depending on the location and intensity of the treatment.

Chemotherapy for Dog Cancer

Chemotherapy is a form of cancer treatment that utilizes medication to destroy cancer cells. It is particularly effective for types of cancer that have metastasized or spread throughout the body, as well as for shrinking tumors prior to surgical removal.

The way chemotherapy drugs work is by targeting rapidly dividing cells, a common characteristic of cancer cells. Unfortunately, this can also affect some of the body's normal cells, such as those within the gastrointestinal tract or hair follicles, which can lead to side effects.

Veterinarians may recommend chemotherapy for your dog when other treatments are not viable or when cancer is too advanced for surgery alone to be effective. It is not a cure-all, but it can significantly prolong the quality and duration of your beloved pet's life when administered appropriately.

Possible side effects of chemotherapy in dogs can differ from those in humans and often are less severe. Some dogs might experience symptoms including but not limited to mild nausea, temporary decrease in appetite, and just like humans, a level of fatigue after treatment. It’s noteworthy that dogs rarely lose their fur, but certain breeds with continuously growing hair may experience some thinning.

Holistic Treatments for Dog Cancer

Holistic treatments are therapies that aim to treat the whole patient, not just the disease. They can include a range of therapies, such as acupuncture, herbal medicine, nutrition therapy, and physical therapy. While holistic treatments are not typically used as the primary treatment for dog cancer, they can complement conventional treatments by helping to manage symptoms, reduce side effects, and improve overall quality of life. For example, acupuncture can help manage pain and nausea associated with cancer treatments, while nutrition therapy can help maintain your dog's strength and vitality during treatment. At CodaPet, we're here to provide the guidance and resources you need to explore holistic treatment options for your pet, and to support you and your pet through the process.

Early Detection and Prevention

Importance of Early Detection

Early detection of cancer can significantly improve the prognosis for your pet. Many types of cancer are more treatable when they're caught early, before they've had a chance to spread. Regular veterinary check-ups and at-home examinations are key to early detection, as they can help identify lumps and other signs of cancer at their earliest stages. Signs and symptoms that might indicate cancer include new lumps or changes in existing lumps, unexplained weight loss, loss of appetite, lethargy, and changes in behavior.

Preventive Measures for Dog Cancer

While it's not always possible to prevent cancer, there are meaningful actions you can take to decrease your dog’s risk and catch it early if it does develop. Providing your dog with a balanced diet rich in antioxidants can support their immune system and overall health, which might be a factor in cancer prevention. Regular exercise not only keeps your dog physically fit but also helps reduce the risk of obesity—a known contributor to cancer.

Exposure to carcinogens, such as tobacco smoke, lawn chemicals, and certain household cleaners, can also increase the risk of cancer in dogs. By minimizing these exposures, you can further reduce their risks.

Consistent and proactive veterinary care plays a pivotal role in early cancer detection and prevention. Regular check-ups offer opportunities for veterinarians to spot any health concerns early on, which is critical for successful treatment and recovery. Diagnostic screenings, such as blood tests and imaging, can be essential for catching cancer in its initial stages when it’s most treatable.

Additionally, be aware of genetic predispositions. Some dog breeds are more susceptible to certain types of cancer, which is why a breed-specific approach to prevention and early detection can be beneficial. You can discuss with your veterinarian about any specific measures you should take based on your dog’s breed, size, and risk factors.

Supporting Your Dog During and After Treatment

Supporting your dog during and after cancer treatment is crucial for their well-being. This can include providing a comfortable and stress-free environment, ensuring your dog gets plenty of rest, and feeding them a balanced diet. Managing the side effects of treatment is also important. This might involve giving medications to help control nausea or pain, providing extra comfort and care, and keeping an open line of communication with your vet.

Wrapping Up: Your Dog's Health is in Your Hands

Recognizing the signs of illness early on and being proactive with your dog’s health care are some of the most loving actions you can take as a pet owner. If you're ever faced with the heartbreaking reality of a cancer diagnosis for your cherished companion, remember that you're not walking this path alone. Take the steps outlined above and seek veterinary care and guidance as soon as you can. Early diagnosis, as it is with our human family members, is crucial to helping to increase the possibility of a favorable outcome so you can enjoy many more days and years with your beloved pet.

When the time approaches, long after cancer diagnosis, when our beloved pets need help peacefully passing in the comfort of their homes, CodaPet is here to help guide and support you through the end-of-life experience. Our compassionate CodaPet veterinarians offer in-home support and help with kindness and expertise through this difficult time

As difficult as this journey may be, take heart in knowing that hope and healing are possible. By working closely with your vet and with our dedicated assistance, you can create a nurturing environment for your dog to thrive in, hopefully long beyond their diagnosis. Schedule Home Visit

Dr. Karen Whala

Fresno, CA


Dr. Karen Whala has always had a soft spot for the older pets she’s treated in practice and saw a need for these beloved pets to pass peacefully at home rather than in a clinic setting. To that end, she started Peaceful Passing in 2018 to help families assist their terminally ill, injured, or suffering pets as they transitioned from life in the Fresno and Clovis areas.  Read More

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