As pet owners, it’s natural to worry about the health of our furry companions—especially when it comes to something as serious as cancer. Many people have experienced the heartache of supporting a loved one, whether human or animal, through a cancer diagnosis and treatment. It’s a difficult, emotional journey, and understandably, concerns about cancer often weigh heavily on pet parents.
The good news is that our pets are living longer, healthier lives than ever before. Thanks to advancements in preventative care, early disease detection tools, improved treatments for chronic conditions, and a better understanding of nutrition, dogs and cats today are enjoying extended lifespans.
With this extended longevity, routine blood tests—often part of annual wellness exams—have become a key part of proactive pet care. Many pet owners ask if these tests can help spot signs of cancer before more obvious symptoms appear. In this blog, we’ll dive into how blood tests may offer early clues about cancer and discuss what these routine screenings might reveal about your pet’s overall health.
What Are Blood Tests?
Blood tests can vary in meaning depending on the context, but when you bring your pet in for their annual vet visit, a standard set of tests— called a “minimum database”—is usually recommended. This typically includes a Complete Blood Count (CBC), a chemistry panel, and a urinalysis. These tests provide a snapshot of your pet’s overall health, helping your vet spot any potential issues before they become serious.
In some cases, additional testing may be needed based on your pet’s species, age and medical history. For example, tests for thyroid function, feline leukemia virus, or heartworm disease might be added, depending on the circumstances. These routine blood tests are essential for keeping your pet’s health on track, but it’s important to interpret the results in the context of any symptoms your pet might be experiencing.
It’s also crucial to remember that not all diseases—cancer included—will show up in these tests, so even if the results come back normal, your pet may still need further investigation if they’re showing signs of illness. If any results are abnormal, whether or not your pet has symptoms, it’s important to follow up with additional testing to fully understand what’s going on.
In some cases, additional testing may be needed based on your pet’s species, age and medical history.
CBC Changes That Can Occur with Cancer
A Complete Blood Count (CBC) is an essential diagnostic tool that provides critical information about the number and condition of blood cells in your pet’s bloodstream. The CBC measures the number of red blood cells (RBCs), white blood cells (WBCs), and platelets, all of which play key roles in the body. RBCs are responsible for carrying oxygen throughout the body’s tissues, WBCs are central to immune function and fighting infections, and platelets help form blood clots to stop bleeding when tissues are damaged. Changes in the numbers or appearance of these cells can provide important clues about underlying health problems, including cancer.
White Blood Cells (WBCs)
An elevated white blood cell count, or leukocytosis, can be seen in various types of cancer, especially leukemia. Leukocytosis can also be associated with cancers like lymphoma, mast cell tumors, and other tumors that cause inflammation. Tumors often release inflammatory substances that can trigger an immune response, causing an increase in WBCs even without infection. If the WBC count is elevated, it warrants further investigation to determine the cause, whether it’s cancer, an infection, or another inflammatory condition.
Conversely, a decrease in the number of white blood cells, or leukopenia, can indicate a more serious underlying problem. Since WBCs are produced in the bone marrow, cancers affecting the bone marrow directly (like leukemia, lymphoma, or myeloproliferative disorders) can suppress WBC production, leading to a low WBC count. If low WBCs is found, it is essential to conduct additional testing, such as a bone marrow aspirate, to determine the cause.
Red Blood Cells (RBCs)
Changes in the red blood cell count can also signal the presence of cancer. An increased red blood cell count, known as polycythemia, may be seen in certain cancers, particularly kidney cancer. This is because tumors in the kidney can produce excess erythropoietin (EPO), a hormone that stimulates the bone marrow to produce more RBCs. Polycythemia may also occur in cancers involving the lungs (from low oxygenation) or bone marrow (due to a myeloproliferative disorder, such as polycythemia vera).
On the other hand, a decrease in red blood cells, or anemia, is one of the most common blood abnormalities seen in dogs with cancer. Anemia can result from blood loss due to tumors in the gastrointestinal tract, liver, spleen, bladder or pericardium. Cancer-related anemia can also occur as a result of anemia of chronic disease, where inflammation from cancer slows red blood cell production. Bone marrow involvement by cancer can also lead to reduced RBC production. Anemia often causes symptoms like fatigue, weakness, and pale gums and warrants further testing.
Platelets
Changes in platelet counts can also be indicative of cancer. An increased platelet count, known as thrombocytosis, can occur in response to tumors, especially those in the liver, spleen, or lymphatic system. Cancers often lead to an inflammatory response in the body, stimulating the bone marrow to produce more platelets.
On the other hand, a decreased platelet count, or thrombocytopenia, can occur in cancers that affect the bone marrow, such as leukemia or lymphoma. Thrombocytopenia can also result from blood loss caused by tumors in the intestines, spleen, bladder or liver. Low platelets can lead to symptoms like excessive bruising, nosebleeds, or difficulty clotting, all of which require immediate attention.
As pet owners, staying proactive with regular vet check-ups and understanding the role that routine blood tests play in overall health is essential.
Chemistry Changes That Can Occur with Cancer
A chemistry profile is a blood test that measures various substances in the blood, providing valuable insight into organ function and overall health. Abnormalities in these measurements can point to cancer-related conditions. Below are some of the key chemistry profile abnormalities that may suggest the presence of cancer.
Liver Enzymes
Elevated liver enzymes can indicate liver cancer. Tumors such as hepatocellular carcinoma, hemangiosarcoma, and lymphoma can lead to increased liver enzymes like alkaline phosphatase (ALP) and alanine aminotransferase (ALT). In addition, Cushing’s disease can also elevate ALP levels. Especially in large-breed dogs, Cushing’s disease can be caused by a tumor involving one of the adrenal glands. These changes may warrant further investigation into liver and adrenal health.
Glucose
Hypoglycemia, or low blood sugar, is often seen in cancers such as insulinoma, a tumor of the pancreas that overproduces insulin. Other tumors, including those affecting the liver, gastrointestinal tract, lymphatics, and oral cavity, can also cause hypoglycemia through paraneoplastic mechanisms. These tumors often disrupt the normal metabolic processes, leading to abnormal glucose levels that should prompt further diagnostic evaluation. Symptoms of hypoglycemia can include weakness, lethargy and even seizures.
BUN, Creatinine, SDMA
Abnormal levels of blood urea nitrogen (BUN), creatinine, or symmetric dimethylarginine (SDMA) can point to kidney disease, which could be cancer. Tumors directly affecting the kidneys or those that metastasize to the kidneys can impair renal function and lead to elevated kidney values.
Calcium
Elevated blood calcium levels, or hypercalcemia, is an important cancer marker, especially in dogs. Cancers of bone (osteosarcoma), anal sac adenocarcinoma and lymphoma are cancers that cause increased calcium levels. Parathyroid tumors, which may be benign or malignant, can also result in elevated calcium levels (hyperparathyroidism). In cats, the most common cause of hypercalcemia is called idiopathic hypercalcemia, which is a non-malignant disease but still requires attention due to its potential impact on the urinary system and overall health.
Electrolytes (Sodium, Potassium)
Abnormalities in electrolytes can point to adrenal tumors, particularly those causing hyperaldosteronism. This condition leads to the overproduction of aldosterone, a hormone that regulates sodium and potassium levels. Elevated sodium and decreased potassium are common findings in cases of hyperaldosteronism, and adrenal tumors should be considered if these imbalances are detected.
Globulins
Increased globulin levels can indicate the presence of certain cancers like multiple myeloma (MM) and lymphoma. In MM, cancerous plasma cells produce excess immunoglobulins, leading to an elevated globulin level in the blood. Similarly, lymphoma, a cancer of the lymphatic system, can cause increased globulin levels due to the overproduction of immune cells.
Bilirubin
Elevated bilirubin levels can indicate liver, gallbladder, bile duct, or pancreatic cancer. When cancer affects the liver or its bile ducts, it can interfere with the normal metabolism and excretion of bilirubin, leading to jaundice (yellowing of the skin or eyes) and elevated levels in the blood. Pancreatic cancer can block the excretion of bile from the liver, leading to increased bilirubin levels. Increase in bilirubin should prompt further evaluation of the liver and surrounding organs.
Conclusion
Routine blood tests play a crucial role in monitoring the health of our pets, helping veterinarians identify potential health issues before they become more severe. While these tests are not a definitive diagnostic tool for cancer, they can provide early clues that warrant further investigation. Abnormalities in the Complete Blood Count (CBC) and chemistry profile—such as changes in white blood cells, red blood cells, platelets, liver enzymes, glucose levels, and other markers—can suggest the presence of cancer or related conditions.
By catching these changes early, blood tests can help veterinarians detect cancer sooner, leading to better outcomes and treatment options. However, it’s important to remember that many of these changes can also be associated with other health issues, so additional diagnostic testing is often needed to confirm a cancer diagnosis.
As pet owners, staying proactive with regular vet check-ups and understanding the role that routine blood tests play in overall health is essential. If any abnormalities are found in these tests, working closely with your veterinarian to explore further testing and treatment options can help ensure the best possible care for your pet. Early detection is key to managing your pet’s health, and routine blood tests are one important step in that process.
Contact Us
Abnormal blood work can be confusing, and concerning symptoms can be alarming. Don’t try to navigate this alone. Contact us today, and let us help you understand the situation and develop a plan to get your pet back to their happy, healthy selves.
Author:
James Woods DVM, MS, DACVIM (SAIM)
Ph: (912) 721-6410
Contact Us
