Does Rover Have Cancer? How Bloodwork Can Reveal Your Dog’s Health


Cancer is a leading cause of death in dogs, with studies estimating that 1 in 4 dogs will develop cancer at some point during their lifetime [1]. While cancer can affect dogs of any breed or age, older dogs and certain breeds like Golden Retrievers, Boxers, and Rottweilers are at increased risk [2]. The most common cancers found in dogs include lymphoma, mammary gland tumors, skin cancer, bone cancer, and blood cancer.

Early detection of cancer greatly improves treatment success and survival chances. Veterinary organizations recommend annual screening tests starting from around age 7 to catch cancer early, before symptoms appear [2]. Bloodwork is one important diagnostic tool for detecting cancer and assessing overall health in dogs.

What is Cancer in Dogs?

Cancer refers to the uncontrolled growth of abnormal cells in the body. It develops when normal cells undergo genetic mutations that allow them to multiply rapidly and spread into surrounding tissues [1].

In dogs, cancer usually originates from a single mutated cell that starts dividing out of control. As more cancer cells amass, they form a growth or tumor. Benign tumors are not cancerous, while malignant tumors are cancerous and can invade nearby tissues [2].

There are over 100 different types of cancer that can affect dogs. Some of the most common cancers in dogs include lymphoma, mast cell tumors, melanoma, osteosarcoma, and mammary gland tumors.

Cancer cells can also break off from the original tumor and spread to other parts of the body through the bloodstream or lymph system, forming secondary tumors. This process of spreading is called metastasis [3].

Common Signs of Cancer

There are several common signs that may indicate cancer in dogs. Some of the most frequent signs of cancer in canines include:

  • Unusual lumps or bumps on or under the skin – These may be tumors or abnormal growths associated with various cancers like mast cell tumors or lymphoma (source).
  • Abnormal swelling that persists or continues to grow – This could signal cancers like lymphoma, osteosarcoma, or soft tissue sarcomas (source).
  • Unexplained weight loss – Cancers like lymphoma, oral melanoma, and others can cause dogs to lose weight unexpectedly (source).
  • Loss of appetite or difficulty eating – Oral cancers or cancers affecting the gastrointestinal tract may make eating uncomfortable or difficult for dogs (source).
  • Lameness or stiffness – Bone cancers like osteosarcoma can cause pain or mobility issues in dogs’ legs (source).
  • Abnormal bleeding or discharge – Bleeding from the nose, mouth, or genitals or other abnormal discharges may indicate cancer (source).
  • Offensive odors – Some oral, skin, or glandular tumors can produce foul odors emanating from dogs (source).

Other general signs like lethargy, vomiting, diarrhea, coughing, or labored breathing could also potentially indicate cancer, especially when they persist. It’s important to monitor dogs for any unusual changes and have them assessed promptly by a veterinarian.

Importance of Bloodwork

Bloodwork is a crucial tool for detecting cancer and aiding in diagnosis in dogs. There are certain blood tests that can pick up indicators of cancer or rule out other possible causes for a dog’s symptoms. According to Wired, “veterinarians analyze these markers to determine whether an animal needs more specific cancer screens” (

Some key components of bloodwork for detecting cancer include:

  • Complete blood count (CBC) – Checks levels of red blood cells, white blood cells, and platelets. Elevated white blood cell count can indicate inflammation or infection that may be related to cancer.
  • Biochemical profile – Measures organ function through levels of enzymes, proteins, electrolytes. Abnormal levels can signal issues like liver or kidney problems which may be tied to cancer.
  • Specific tumor markers – Substances like alkaline phosphatase can be elevated with certain cancers like osteosarcoma.

While most routine bloodwork cannot conclusively diagnose cancer, it provides veterinarians with clues that can aid in determining if further testing like biopsies or imaging are warranted. According to MedVet, “bloodwork helps create suspicion of cancer and indicates body systems affected by the disease” ( Early detection is key for more positive outcomes, so bloodwork is a simple, non-invasive first step.
veterinarian drawing blood from dog's vein

Complete Blood Count

A complete blood count (CBC) is one of the most common tests vets use to screen for cancer and other illnesses in dogs. The CBC provides important information about the different types of cells in your dog’s blood. It measures the number, size, and shape of red blood cells, white blood cells, and platelets. Abnormalities in these cell populations can indicate cancer or other diseases.

Some key markers in the CBC that may raise suspicion of cancer include:

  • Anemia – This is indicated by low red blood cell counts, low hemoglobin levels, or low hematocrit (percentage of red blood cells in the blood). Certain cancers like leukemia can suppress normal blood cell production in the bone marrow, leading to anemia.
  • High white blood cell count – Also called leukocytosis, this can signify the presence of infection, inflammation, stress, or bone marrow cancer such as leukemia. Specific types of white blood cells may also be increased.
  • Abnormal white blood cell morphology – Cancer may cause immature white blood cells or abnormal looking cells to appear.
  • Thrombocytosis – High platelet counts, which can occur with certain cancers like lymphoma.

While none of these are definitive for cancer, they provide clues that further testing may be warranted if cancer is suspected. The CBC is often used as an initial screening test, but your vet may recommend more specific follow up testing if any results are concerning.


Biochemical Profile

microscope slide of dog blood cells

A biochemical profile is a common blood test that measures different substances in a dog’s blood, including enzymes, electrolytes, fats, and proteins (Wagwalking, 2021). This provides important information about how well a dog’s organs are functioning, which can help identify underlying health issues like cancer.

Some key components measured in a dog’s biochemical profile include:

  • Kidney tests like BUN and creatinine
  • Liver enzymes like ALT, AST, and ALP
  • Proteins like albumin and globulin
  • Electrolytes like calcium, phosphorus, and magnesium
  • Blood glucose

Abnormalities in these biochemical parameters may indicate possible cancer, especially in the liver or kidneys where tumors often develop in dogs. Elevated liver enzymes, for example, can signal liver inflammation or damage that may be caused by cancer (Sánchez-Solé et al., 2021). Low albumin can also occur with some canine cancers as they inhibit protein production.

While not definitive on its own, a biochemical profile provides key data points for vets to analyze when considering a cancer diagnosis. It helps complete the clinical picture along with other tests.

Other Tests

In addition to a complete blood count and biochemical profile, veterinarians may recommend other tests to check for signs of cancer in dogs, such as:

  • Urinalysis – Examining a urine sample under a microscope can reveal the presence of blood, bacteria, crystals, and cancer cells, which may indicate bladder cancer or other urinary tract problems.

  • Imaging – X-rays, ultrasound, CT scans, and MRI can allow veterinarians to visualize tumors or abnormalities in organs and tissues. While not definitive, imaging can help locate masses for biopsy.

  • Biopsy – Removing a small sample of tissue for examination under a microscope is the most accurate way to diagnose cancer. The biopsy can determine if the cells are cancerous.

While some blood tests may not directly indicate cancer, urinalysis, imaging, and biopsy can help veterinarians arrive at a cancer diagnosis in dogs. These tests allow closer examination of the potential problem area.

Interpreting Results

Interpreting blood test results in dogs requires comparing the values against normal reference ranges. While some minor fluctuations are normal, significant deviations often indicate an underlying health issue. Veterinarians carefully analyze the complete blood count (CBC), biochemistry profile, and other test results to uncover abnormalities.

The CBC reports levels of red blood cells, white blood cells, platelets, and hemoglobin. Low red blood cell counts (anemia) may suggest blood loss, destruction of red blood cells, or bone marrow problems. High white blood cell counts can indicate inflammation, infection, stress, or bone marrow disease. Low platelet counts may indicate bleeding disorders or bone marrow abnormalities, while high platelets can signify infections, inflammation, or bone marrow tumors.

The biochemistry profile measures enzymes, electrolytes, lipids, sugars, and proteins. Elevated liver enzymes like ALT, AST, and ALP often indicate liver disease or damage. High BUN and creatinine levels suggest kidney dysfunction. Abnormal calcium, phosphorus, or sodium levels can point to hormonal abnormalities, kidney disease, cancer, or other conditions. Increased glucose may indicate diabetes, while low cholesterol could signify liver disease, infection, or cancer.
veterinarian reviewing lab test results

Urinalysis assesses urine concentration, chemical composition, and sediment to uncover issues like urinary tract infections, kidney disease, diabetes, and bladder cancer. Testing for heartworm antigens and tick-borne diseases like Lyme disease, anaplasmosis, and ehrlichiosis is also important. Imaging tests like X-rays, ultrasounds, CT scans, and MRIs help detect tumors, organ damage, and other structural abnormalities (Source 1).

While normal blood work does not completely rule out cancer or other diseases in dogs, significant abnormalities often provide the first clues, prompting further testing. Veterinarians consider blood test results along with a pet’s symptoms and medical history to make an accurate diagnosis and determine the best treatment plan.

Treatment Options

There are several treatment options for cancer in dogs, and determining the best course will depend on factors like the type of cancer, its stage and grade, your dog’s age and health, your financial resources, and more. According to the AKC, some common treatment options include:

  • Surgery – Removing the tumor surgically, whether in whole or in part.
  • Chemotherapy – Using anti-cancer drugs to kill cancer cells and shrink tumors.
  • Radiation – Using targeted radiation to kill cancer cells and reduce tumor size.
  • Immunotherapy – Using the body’s immune system to fight cancer cells.
  • Targeted therapy – Using drugs that specifically target cancer cells based on their molecular makeup.
  • Cryosurgery – Freezing and destroying abnormal cells using liquid nitrogen.

Your vet may recommend combining multiple treatments, like surgery followed by chemotherapy or radiation. According to Prism Vet Health, other supportive or alternative options may include pain management, nutritional therapy, physical therapy, and Chinese herbs.

The treatment plan for your dog will depend on the type and extent of their cancer. Be sure to discuss all options thoroughly with your vet to determine the best approach. Factors like your dog’s quality of life and prognosis will help guide difficult treatment decisions.

The Importance of Veterinary Care

Seeing a vet regularly is crucial for detecting cancer early in dogs. Wellness exams allow vets to establish a baseline for your dog’s health and notice any changes over time. Having your vet look for signs of cancer at annual exams, especially as your dog ages, can help identify issues before they become more advanced. According to The Vetverse, “early-stage detection leads to better outcomes for a variety of cancer types” (1).

It’s also essential to consult a vet as soon as you notice any potential symptoms of cancer in your dog. Signs like abnormal swelling, sores that don’t heal, difficulty eating, or sudden lethargy warrant an immediate vet visit (2). Early intervention can make cancer treatment more effective. Don’t wait to see if symptoms resolve on their own, as that delays diagnosis. Your vet can run tests to determine if cancer is the cause of your dog’s issues. As DVM360 states, “the power to detect, manage, and potentially change the course of cancer lies in the hands of the primary care veterinarian” through regular visits (3). Staying on top of your dog’s health with a vet is key for early cancer detection.
owner scheduling appointment with veterinarian


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