Cancer in Dogs: Causes, Symptoms & Treatment

Cancer, a formidable adversary, knows no boundaries and can affect not only humans but also our cherished canine companions. Diagnosing cancer in a beloved pet can be a heart-wrenching moment for any dog owner.

In this guide, we will discuss the various types of cancer that can affect dogs, the causes, diagnosis, symptoms, and treatment options of cancer in dogs.

Cancer is a pervasive health concern among dogs, and it can manifest in various forms. Below, we explore some of the most common types of cancer found in dogs:

1. Canine Lymphoma (Lymphosarcoma)

• Lymphoma, or lymphosarcoma, is a prevalent form of cancer in dogs. This cancer most commonly manifests as the enlargement of multiple lymph nodes throughout the body. 
• These lymph nodes are small structures found in various regions including internal organs.
• While lymphoma is rarely curable, its diagnosis is usually straightforward. A small needle is used to obtain a sample from one of the enlarged lymph nodes (fine needle aspirate), which a pathologist then examines to confirm the presence of the disease.

2. Bone Tumours (Osteosarcoma)

• Bone cancer in dogs predominantly originates within one of their limbs.Warning signs often include lameness and swelling at the site of the tumour.
• Its treatment typically involves amputation of the affected limb, followed by several chemotherapy treatments with the drug carboplatin.

3. Mast Cell Tumours

• Mast cell tumours are the most common skin tumours found in dogs. These tumours typically arise on or just below the skin's surface, although they can occasionally develop inside the chest or abdominal cavities.
• Although not every dog can be cured of mast cell cancer, numerous treatment options can significantly prolong survival while maintaining an excellent quality of life.

4. Hemangiosarcoma

• Hemangiosarcoma is a highly aggressive cancer that originates in the blood vessel walls. Hemangiosarcoma can affect various organs, with the most common sites being the heart and spleen.
•  It is often called "the silent killer" because it tends to go unnoticed until it reaches an advanced stage. Its treatment options are often limited due to the advanced stage at diagnosis.

5. Transitional Cell Carcinoma

• Transitional Cell Carcinoma is a type of cancer that can affect dogs, primarily in their urinary tract. 
• It most commonly develops in the bladder but can also occur in the urethra and other parts of the urinary system.

Cancer in dogs has various causes and risk factors. While it's not always possible to pinpoint a single cause for cancer development, it's important to know many factors and causes that lead to cancer, which include:

• Genetics: Some breeds have a higher predisposition to specific types of cancer due to their genetic makeup. For example, breeds like the Golden Retriever and Boxer are more prone to lymphoma, while large breeds are at a higher risk of developing bone cancer (osteosarcoma).
• Age: Older dogs are more susceptible to various types of cancer, such as mammary tumours and skin cancers. 
  
• Environmental Factors: Exposure to certain environmental factors can contribute to cancer in dogs. These factors include secondhand tobacco smoke, pesticides and herbicides, and ultraviolet (UV) radiation.
  
• Diet and Nutrition: A poor diet or overfeeding can impact a dog's health and potentially contribute to cancer development. Obesity, in particular, has been linked to an increased risk of cancer in dogs.
  
• Viral Infections: Some viral infections can increase the risk of cancer in dogs. For instance, the canine papillomavirus is associated with developing oral squamous cell carcinoma.
  
• Lifestyle Factors: Certain lifestyle factors, including lack of exercise and chronic stress, can weaken a dog's immune system and potentially contribute to cancer development. Regular physical activity and a stress-free environment are beneficial for overall health.
  

Cancer in dogs can manifest in various ways, and the signs may differ depending on the type, location, and stage of the cancer. Common symptoms of cancer in dogs include:

• Lumps and Bumps: The most visible sign in skin tumours is the presence of lumps or bumps on or just below the skin's surface.
• Lethargy: Unexplained lethargy or a significant decrease in energy levels can indicate illness, including cancer.
  
• Vomiting and Diarrhoea: Chronic or unexplained vomiting and diarrhoea can indicate underlying issues, including gastrointestinal cancers.
  
• Blood in Stool: Blood in the stool should always be investigated, as it can be a sign of various conditions, including colorectal cancer.
  
• Coughing: Persistent or chronic coughing, especially with blood, can indicate lung cancer.
  
• Dental Problems: Dental issues that don't improve with treatment can be a sign of oral cancer.
  
• Urinary Issues: Frequent urination, difficulty urinating, or blood in the urine may be signs of urinary tract or bladder cancer.
  
• Swollen Lymph Nodes: Enlarged lymph nodes in the neck, armpits, or groin can be a sign of lymphoma or other cancers.
  
• Recurrent Infections: Dogs with weakened immune systems may be more susceptible to infections due to cancer.
  
• Neurological Symptoms: Dogs with brain tumours may experience seizures, varying in severity and frequency. They can also experience confusion and disorientation.
  

Diagnosing cancer in dogs involves a combination of clinical assessments, diagnostic tests, and procedures. Here are the key steps in diagnosing dog cancer:

1. Physical Examination

• Palpate for Lumps and Bumps: The vet will check for any palpable lumps, tumours, or abnormalities on or beneath the skin.
• Assess Vital Signs: Vital signs, including temperature, heart rate, and respiratory rate, are measured to evaluate the dog's overall health.
  
• Examine Mucous Membranes: The colour and condition of the gums and other mucous membranes are assessed.
  
• Evaluate Body Condition: The dog's body condition, weight changes, and any visible symptoms are noted.
  
• Check for Pain and Discomfort: Observe the dog's reaction to touch and movement, as pain or discomfort can indicate cancer.
  

2. Diagnostic Imaging

• X-rays: X-rays are commonly used to detect tumours in the chest, abdomen, and bones. They are especially useful for identifying lung tumours, bone cancer, and the spread of cancer to other organs.
• Ultrasound: Ultrasound can visualise soft tissues and organs in real-time. It is often used to assess abdominal tumours, including those in the liver, spleen, and gastrointestinal tract.
  
• CT Scan: A computed tomography (CT) scan provides detailed cross-sectional images and is valuable for identifying the extent of tumour involvement in various organs.
  

3. Blood Tests

Blood tests may be conducted, including a complete blood count (CBC) and a biochemical profile. These tests help evaluate the dog's overall health and can provide insights into potential abnormalities associated with cancer, such as changes in blood cell counts or organ function.

4. Fine Needle Aspiration (FNA)

A small sample of cells is collected from a suspicious lump or mass using a fine needle. These cells are examined under a microscope to determine if they are cancerous. FNA is commonly used for diagnosing skin tumours and some internal masses.

5. Surgical Biopsy

Sometimes, a surgical biopsy may be necessary to obtain a larger tissue sample for a definitive cancer diagnosis. This involves the removal of a portion or the entire tumour, and the tissue is sent to a pathologist for analysis.

6. Histopathology

Histopathology involves the microscopic examination of tissue samples collected during biopsies or surgeries. A pathologist analyses the tissue to determine the type of cancer, stage, and grade (aggressiveness). This information guides treatment decisions.

The treatment journey for canine cancer often involves a multidisciplinary approach to eradicating or managing the disease. The primary treatment modalities include:

• Surgery: Whenever feasible, complete removal of a tumour is performed through surgery. The extent of surgery depends on factors such as tumour size, location, and type.
• Debulking Surgery: In cases where complete removal of a tumour isn't possible, debulking surgery may be performed to reduce the tumour's size, making it more manageable for other treatments like radiation or chemotherapy.
  
• Limb Amputation: For bone cancers like osteosarcoma, amputation of the affected limb is often recommended. This procedure aims to relieve pain and improve the dog's quality of life. It is usually followed by chemotherapy to target any remaining cancer cells.
  
• Chemotherapy: Administering chemotherapy drugs can shrink tumours, slow their growth, or eliminate cancer cells that have spread to other body parts.
  
• Radiation Therapy: This localised treatment involves directing high-energy beams at cancerous tissue to destroy or damage cancer cells.
  
• Immunotherapy: Immunotherapy is an emerging field in treating dog cancer, where the dog's immune system is activated to target and destroy cancer cells.
  
• Palliative Care: In cases where a cure is not possible, palliative care focuses on improving the dog's quality of life and managing cancer-related symptoms. This may include pain management, nutritional support, and strategies to enhance comfort.

Recovery after cancer treatment can be challenging for dogs and their owners. Here are some crucial aspects to consider during this period:

• Dietary Modifications: Proper nutrition is vital for rebuilding strength, maintaining a healthy weight, and supporting the immune system. This might involve special diets rich in nutrients like protein, vitamins, and minerals. 
• Monitoring for Side Effects: Common side effects of chemotherapy, for example, can include nausea, vomiting, diarrhoea, and fatigue. Keep a close eye on your dog's behaviour and health during this time. 
  
• Physical Therapy and Exercise: Physical therapy can benefit dogs recovering from cancer treatment, especially if they've undergone surgery or experienced mobility issues. Your veterinarian or a certified canine rehabilitation therapist can create a tailored exercise plan to help your dog regain strength and mobility.
  
• Emotional Support: Maintain a stable and comforting environment for your dog. Spend quality time with them, engage in enjoyable activities, and offer plenty of love and reassurance.
  
• Regular Veterinary Check-Ups: Continued monitoring of your dog's health is essential post-treatment. Schedule regular check-ups with your veterinarian to assess the progress of recovery, monitor for any recurrence of cancer, and promptly address any emerging health issues.
  

Therefore, cancer in dogs is a complex and emotionally challenging issue, but with knowledge, early detection, and access to advanced treatments, many dogs can experience an improved quality of life.  Dog owners who are vigilant in monitoring their pets for any signs of cancer, such as lumps, changes in behaviour, or unexplained weight loss can get early detection and timely treatment.