12 Types of Cancers in Dogs and Cats You Need to Know

November 14, 2023

Just like humans, dogs and cats can get cancer too. It’s a tough challenge they might have to deal with Pet parents need to understand to know what the symptoms of cancer are and how can support and help our beloved pets. With time pet parents have become conscious than ever. Early detection is the linchpin to effective treatment and ensuring our pets’ well-being. 

Let’s discuss cancer in dogs as well as cats in detail. We will explore the 12 most prevalent types of cancer affecting them, discussing their nuances, symptoms, risk factors, and the latest treatment options. By the end of this blog, you will be able to understand and catch early symptoms in your pet. Now let’s get started!  

12 Types of Cancers in Dogs and Cats

  • Lymphoma 
  • Osteosarcoma 
  • Mast Cell Tumors 
  • Melanoma 
  • Hemangiosarcoma 
  • Mammary Gland Tumors 
  • Leukemia 
  • Squamous Cell Carcinoma 
  • Bladder Cancer 
  • Gastrointestinal (GI) Cancer 
  • Brain Tumors 
  • Sarcomas 

1. Lymphoma

Lymphoma is one of the most prevalent and complex cancers that can affect our dogs and cats. It arises from the lymphatic system, which plays a vital role in maintaining the body’s immune function. This form of cancer can manifest in various parts of the body, making it crucial to grasp its nature, signs, and available treatments. 

Understanding Lymphoma

Lymphoma, also known as lymphosarcoma, is a type of cancer that originates in the lymphocytes, a type of white blood cell found in the lymphatic system. It can affect both dogs and cats and is characterized by the abnormal proliferation of these cells. Lymphoma can manifest in different forms, including multicentric (affecting multiple lymph nodes), dietary (in the gastrointestinal tract), cutaneous (skin-based), and more. 

Symptoms of Lymphoma

  • Enlarged lymph nodes 
  • Weight loss 
  • Decreased appetite 
  • Lethargy 
  • Vomiting and diarrhea 
  • Increased thirst and urination 
  • Difficulty breathing 
  • Skin lumps or lesions in cutaneous lymphoma 


If you suspect your pet might have lymphoma, consult your veterinarian immediately. Diagnosis typically involves a combination of physical examination, blood tests, and imaging such as X-rays or ultrasound. A definitive diagnosis is often made by examining lymph nodes or tissue samples through a biopsy. 

2. Mast Cell Tumors

Mast cell tumors are a common type of skin cancer that can affect our beloved pets. These tumors originate from mast cells, a type of immune cell found in the skin and other tissues. These tumors vary in appearance and can appear as lumps or raised bumps on the skin. While some are benign, others can be malignant and aggressive. 

Signs of Mast Cell Tumors

  • Skin lumps or nodules 
  • Swelling and redness around the lump 
  • Itching or discomfort at the tumor site 
  • Gastrointestinal symptoms if the tumor is in the stomach or intestines 
  • Ulceration or bleeding from the tumor 


To diagnose mast cell tumors, your veterinarian will conduct a physical examination and may perform a fine-needle aspirate or biopsy to analyze the tumor cells. Further tests, such as bloodwork and imaging, may be necessary to determine the extent of the disease. 

3. Osteosarcoma

Osteosarcoma is the most common primary bone tumor in dogs. It often occurs in the long bones of the limbs, such as the leg bones. Osteosarcoma is highly invasive and can quickly spread to other parts of the body. 

Common Symptoms

  • Limping or lameness 
  • Swelling or a palpable mass at the tumor site 
  • Pain and discomfort, especially during physical activity 
  • Fractures or breaks in affected bones 


Diagnosis usually involves X-rays, CT scans, or biopsies to confirm the presence of osteosarcoma. This information helps determine the extent of the disease and potential treatment options. 

4. Hemangiosarcoma

Hemangiosarcoma is a highly aggressive and malignant cancer that primarily affects the blood vessels in dogs and, less commonly, in cats. It usually originates in the spleen, heart, or liver but can spread to other organs. 

Warning Signs

Dogs: Common warning signs in dogs include weakness, lethargy, pale gums, abdominal swelling, and collapse, often due to internal bleeding. 

Cats: Hemangiosarcoma is rarer in cats, and its clinical signs may be similar to those in dogs, such as weakness and pale gums. Cats may also exhibit signs of abdominal discomfort. 

Diagnostic Techniques

Veterinarians typically use a combination of diagnostic methods to confirm hemangiosarcoma. Definitive diagnosis often requires histopathology, which involves analyzing tissue samples obtained through surgery or biopsy. 

Treatment Options

Hemangiosarcoma is challenging to treat, and the prognosis is generally poor due to its aggressive nature. Treatment may involve surgical removal of the tumor if possible, followed by chemotherapy. In some cases, emergency surgery to address internal bleeding may be necessary. 

5. Mammary Gland Tumors in Female Dogs and Cats

Mammary gland tumors are relatively common in female dogs and cats. These tumors can be benign (non-cancerous) or malignant (cancerous). They typically occur in unspayed or late-spayed females. Early detection and prompt treatment are essential for the best possible outcome. 

Early Detection

Pet owners should routinely check their female dogs and cats for any lumps or abnormalities in the mammary glands. Early tumors are often small and firm, and they can be mistaken for small pebbles under the skin. 

Prompt Veterinary Examination: If a lump or mass is detected, it’s crucial to consult a veterinarian. They can perform a thorough physical examination and recommend further diagnostic tests. 


Surgery: The primary treatment for mammary gland tumors is surgical removal. The entire chain of mammary glands may need to be removed, which is why early detection is crucial. Spaying the pet at the time of surgery is often recommended to reduce the risk of recurrence. 

Biopsy and Staging: A biopsy of the tumor is necessary to determine its type and aggressiveness. Staging helps assess whether the cancer has spread to nearby lymph nodes or other organs, influencing the treatment plan. 

Additional Treatments: Depending on the tumor’s type and stage, additional treatments such as chemotherapy or radiation therapy may be recommended to further reduce the risk of recurrence or metastasis. 

6. Melanomas

Melanoma is a type of skin cancer that can affect dogs and, to a lesser extent, cats. It originates in the melanocytes, the pigment-producing cells of the skin, and can be highly aggressive if not detected and treated early. 


Melanomas often appear as dark, pigmented growths on the skin. These growths may be flat or raised and can sometimes resemble moles or warts. They may also change in size, color, or shape over time. 

Oral Melanoma (In Dogs): In dogs, oral melanomas are more common than cutaneous (skin) melanomas. Symptoms can include swelling, bleeding from the mouth, difficulty eating, and bad breath. 

Lymph Node Enlargement: If melanoma has spread (metastasized), lymph nodes may become enlarged. 


Biopsy: To confirm a melanoma diagnosis, a biopsy is performed. In some cases, fine needle aspiration is used to obtain a tissue sample for examination. 

Staging: If melanoma is diagnosed, staging is done to determine the extent of the disease. This may include imaging studies like X-rays, ultrasound, or CT scans. 

7. Squamous Cell Carcinoma in Pets

Squamous cell carcinoma (SCC) is a type of cancer that can affect both dogs and cats. It typically arises from the squamous cells, which are found in the skin, mucous membranes, and other tissues. SCC can occur in various areas of the body. 


Skin SCC: In pets, skin SCC often presents as non-healing ulcers, raised lumps, or scaly lesions on the skin, particularly in areas exposed to sunlight. 

Oral SCC: In cats, oral SCC is relatively common and can cause symptoms like drooling, difficulty eating, and bad breath. In dogs, it can also occur in the mouth and may cause similar signs. 

Nasal SCC: Nasal SCC in dogs and cats can lead to nasal discharge, difficulty breathing, sneezing, and sometimes facial swelling. 


  • A biopsy is usually necessary to confirm SCC. Tissue samples are taken from the affected area and examined under a microscope. 
  • Radiographs (X-rays) or advanced imaging like CT scans may be used to assess the extent of the tumor and any potential metastasis. 

8. Bladder Cancer

Bladder cancer is less common in pets than in humans but can still occur in both dogs and cats. The most common type is transitional cell carcinoma (TCC). 

Common Symptoms

  • Bladder cancer often causes urinary symptoms, including blood in the urine, straining to urinate, frequent urination, and urinary accidents in the house. 
  • Pets with bladder cancer may exhibit signs of pain and discomfort in the lower abdominal area. 
  • As the disease progresses, pets may become lethargic and lose weight. 

Diagnostic Procedures

Urinalysis: Urinalysis can reveal blood in the urine and other abnormalities. 

Imaging: Imaging studies such as ultrasound or contrast radiography may be used to visualize the bladder and any tumors within it. 

Biopsy: A biopsy may be performed to confirm the diagnosis and determine the type of cancer. 

9. Brain Tumors in Pets

Brain tumors can occur in both dogs and cats, though they are relatively rare. These tumors can be primary (originating in the brain) or secondary (metastasizing from another location). Primary brain tumors in pets are most commonly gliomas or meningiomas. 


  • Signs may include seizures, changes in behavior, circling, head pressing, loss of coordination, and paralysis. 
  • Pets may exhibit altered mental states, such as disorientation, confusion, and abnormal vocalizations. 

Diagnostic Methods:

  • A thorough neurological examination by a veterinarian is often the first step in diagnosing a brain tumor. 
  • Advanced imaging, such as MRI or CT scans, is necessary to visualize the brain and identify the tumor. 
  • In some cases, a sample of cerebrospinal fluid may be collected to assess for abnormalities or the presence of cancer cells. 

10. Lung Cancer

Lung cancer can occur in both dogs and cats, and it is often categorized as primary (originating in the lung) or secondary (metastasizing from another site). The most common primary lung cancer in pets is carcinoma. 


  • Coughing 
  • Difficulty breathing  
  • Rapid breathing 
  • Wheezing 
  • Lethargy and Weight Loss 


Radiography (X-rays): Chest X-rays are commonly used to identify lung tumors and assess their size and location. 

Fine Needle Aspiration or Biopsy: A sample of lung tissue may be obtained through aspiration or biopsy to confirm the diagnosis and identify the type of cancer. 

CT Scans: Advanced imaging, such as CT scans, can provide more detailed information about the tumor’s extent and characteristics. 

11. Oral Tumors

Oral tumors are relatively common in both dogs and cats, and they can manifest as benign or malignant growths in the mouth, gums, tongue, or throat. 

Prevalence: Oral tumors account for a significant proportion of tumors in the head and neck region in pets. 

Warning Signs

  • Drooling 
  • Difficulty Eating 
  • Oral Bleeding 
  • Bad Breath 

Diagnostic Techniques

A veterinarian will perform a thorough oral examination to assess the size, location, and characteristics of the tumor. A biopsy is essential to determine if the tumor is benign or malignant. X-rays or CT scans may be used to evaluate the extent of the tumor and potential involvement of nearby structures. 

12. Leukemia

Leukemia is a type of cancer that primarily affects the bone marrow and blood cells in both dogs and cats. Leukemia can be classified into different types, including lymphocytic leukemia and myelogenous leukemia. 


  • Lethargy: Affected pets may appear lethargic and have decreased energy levels. 
  • Weakness: Leukemia can lead to weakness and exercise intolerance. 
  • Pale Gums: Pale gums and mucous membranes may be indicative of anemia, a common symptom in leukemia. 


Blood Tests: Blood tests, such as a complete blood count (CBC) and a blood smear, are performed to evaluate the type and extent of leukemia. 

Bone Marrow Aspiration: A bone marrow aspiration may be necessary to confirm the diagnosis and determine the specific type of leukemia. 

Treatment Options for Cancer in Dogs and Cats:  

The treatment approach for Cancer depends on various factors, including the stage and type of lymphoma, your pet’s overall health, and your personal preferences. Common treatment options include Chemotherapy, Steroids, Radiotherapy, etc.  

Cancer is as common as any other disease in dogs or cats. It can impact your pet’s well-being. Understanding exactly what your pet might be feeling can be challenging. That is why we recommend to all pet parents to timely take your pet for veterinarians’ consultation.  

Do not wait for an opportunity when your pet goes through serious illness, after all, prevention is better than cure!  


In conclusion, the key to ensuring the best possible outcomes for pets is regular check-ups with a veterinarian and early detection of any potential health issues, including cancer. If you notice any warning signs or changes in your pet’s health, do not hesitate to consult with a veterinarian.  

Early intervention and appropriate treatment can make a significant difference in the prognosis and quality of life for your beloved companion. Your veterinarian is your best ally in providing guidance, prevention, and treatment options tailored to your pet’s specific needs. 

Frequently Asked Questions:  

What are the most common types of cancer in dogs and cats? 

In dogs, common cancers include lymphoma, mast cell tumors, and osteosarcoma. In cats, lymphoma, squamous cell carcinoma, and mammary gland tumors are frequently seen.

Are there any breed-specific risks for certain cancers in dogs and cats? 

Yes, certain breeds are predisposed to specific cancers. For example, Golden Retrievers are at higher risk for lymphoma, while Siamese cats are more susceptible to mammary gland tumors.

What are the typical signs and symptoms of cancer in dogs and cats?

Warning signs may include lumps or bumps, unexplained weight loss, changes in appetite, lethargy, and difficulty breathing. It’s essential to consult a veterinarian if you notice any of these symptoms. 

How is cancer diagnosed and treated in dogs and cats?

Diagnosis often involves physical exams, blood tests, imaging (X-rays, ultrasounds), and biopsies. Treatment options can include surgery, chemotherapy, radiation therapy, and immunotherapy, tailored to the specific type and stage of cancer. 

Can cancer in pets be prevented or managed with lifestyle changes and early detection?

While cancer can’t always be prevented, maintaining a healthy lifestyle, regular check-ups, and early detection through routine veterinary visits can improve the chances of successful management and treatment. 

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-Petofy India
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