Hemogram in Dogs (Complete Blood Count – CBC) – Everything You Need to Know
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What Is a Hemogram in Dogs and Why Is It Important?
A hemogram, also known as a Complete Blood Count (CBC), is one of the most fundamental diagnostic tests in veterinary medicine. It provides a comprehensive assessment of a dog’s red blood cells (RBCs), white blood cells (WBCs), and platelets (PLTs) — the three main cellular components of blood. Through these parameters, veterinarians can evaluate oxygen transport efficiency, immune system performance, and the body’s ability to clot and maintain internal balance.
The test is performed using a blood sample collected into an EDTA (purple-top) tube. Automated analyzers then measure various hematological indices. The results reflect the dog’s hydration status, age, breed, stress level, and presence of disease. Because blood composition changes dynamically in response to illness, the hemogram serves as an early warning indicator for many systemic disorders.
Veterinarians commonly request a hemogram in the following situations:
Unexplained fever, lethargy, or weight loss
Routine pre-surgical evaluation
Suspected infection, inflammation, or immune-mediated disease
Monitoring during chemotherapy or long-term medication use
Assessment of bleeding or clotting abnormalities
In many cases, hemogram changes appear before clinical signs become obvious, making it one of the most valuable tools for early detection and preventive care in dogs.
Normal Hemogram Values and Their Interpretation in Dogs (Table)
The following table summarizes the average reference ranges for adult dogs and their clinical significance. Values can vary slightly depending on laboratory methods, analyzer type, and individual physiological factors, so interpretation should always consider the lab-specific reference range.
White Blood Cells (WBC) and Their Subtypes in Dogs
White blood cells (leukocytes) are the body’s main defense system against infections and inflammation. The total WBC count provides an overview of immune activity, while the differential count — neutrophils, lymphocytes, monocytes, eosinophils, and basophils — helps determine the nature and stage of a disease process.
Neutrophils
Neutrophils make up 60–80% of total leukocytes in healthy dogs. They are the first responders to bacterial infections and acute inflammation.
Neutrophilia (high neutrophil count) suggests bacterial infection, tissue necrosis, corticosteroid response, or stress.
Neutropenia (low neutrophil count) occurs in viral diseases (e.g., parvovirus), severe sepsis, or bone marrow suppression.
Lymphocytes
Lymphocytes account for 10–30% of total WBCs. They play a crucial role in adaptive immunity and viral defense.
Lymphocytosis occurs in chronic infections, immune-mediated disorders, or lymphoid neoplasia.
Lymphopenia is common during stress, corticosteroid therapy, or viral suppression of bone marrow.
Monocytes
Monocytes are phagocytic cells that migrate to tissues and become macrophages.
Monocytosis usually reflects chronic inflammation, tissue injury, or recovery from acute infection.
Monocytopenia is rare and generally lacks clinical significance.
Eosinophils
Eosinophils are increased in allergic reactions and parasitic infections (intestinal worms, heartworm disease, flea allergy dermatitis).
Basophils
Basophils are the rarest leukocytes and often rise concurrently with eosinophils. They release histamine during allergic responses and play a role in hypersensitivity reactions.
In dogs, evaluating both total WBC and the absolute counts of each leukocyte subtype gives a much more accurate picture than total WBC alone. For example, a combination of neutrophilia and lymphopenia typically indicates a stress leukogram, while eosinophilia combined with basophilia suggests allergic or parasitic etiology.
Red Blood Cells (RBC) and Their Clinical Significance in Dogs
Red blood cells are responsible for oxygen transport to tissues and removal of carbon dioxide from the body. In dogs, the normal RBC count ranges from 5.5 to 8.5 ×10¹²/L. Their number, morphology, and hemoglobin content provide essential information about hydration, oxygenation, and anemia status.
Increased RBC Count (Erythrocytosis or Polycythemia)
A high RBC count may result from:
Dehydration (relative erythrocytosis due to plasma loss),
Chronic hypoxia (dogs living at high altitude),
Polycythemia vera, a rare bone marrow disorder causing excessive RBC production.
Decreased RBC Count (Anemia)
Low RBC values indicate anemia, which can be categorized as:
Blood-loss anemia: Acute hemorrhage from trauma, surgery, or internal bleeding.
Hemolytic anemia: Premature destruction of RBCs due to immune-mediated disease (IMHA), toxins, or infections.
Non-regenerative anemia: Inadequate bone marrow production caused by chronic disease, renal failure, or nutrient deficiency.
To determine the type of anemia, RBC indices (MCV, MCH, MCHC) must be evaluated together.
Low MCV and MCHC: Iron deficiency anemia (microcytic, hypochromic).
High MCV: Regenerative or macrocytic anemia (vitamin B12/folate deficiency).
Normal MCV/MCHC: Chronic disease anemia (non-regenerative).
Microscopic blood smears may also show spherocytes, schistocytes, or Heinz bodies, helping identify immune-mediated or toxic causes of anemia.
Hemoglobin (HGB), Hematocrit (HCT), MCV, MCH, and MCHC Interpretation in Dogs
These parameters collectively describe the oxygen-carrying ability and structural characteristics of red blood cells. Evaluating them together is essential for classifying the type and severity of anemia.
Hemoglobin (HGB)
Hemoglobin is the iron-containing protein inside red blood cells responsible for transporting oxygen. Normal levels in dogs range between 12–18 g/dL.
Low HGB: Indicates anemia, chronic disease, or hemorrhage.
High HGB: Common in dehydration, high-altitude adaptation, or bone marrow disorders such as polycythemia vera.
Hematocrit (HCT)
HCT measures the percentage of blood volume occupied by RBCs (normal range 37–55%).
Decreased HCT: Suggests blood loss, destruction of RBCs, or reduced production (anemia).
Increased HCT: Seen in dehydration, hemoconcentration, or erythrocytosis.
Mean Corpuscular Volume (MCV)
MCV (normal 60–77 fL) indicates the average size of red cells.
Low MCV (microcytic): Iron deficiency, chronic inflammatory disease, or lead poisoning.
High MCV (macrocytic): Regenerative anemia or folate/vitamin B12 deficiency.
Mean Corpuscular Hemoglobin (MCH)
MCH (normal 19–24 pg) represents the amount of hemoglobin per red blood cell. A low MCH indicates hypochromic anemia (cells contain less hemoglobin).
Mean Corpuscular Hemoglobin Concentration (MCHC)
MCHC (normal 32–36 g/dL) expresses hemoglobin concentration within RBCs.
Low MCHC: Hypochromic anemia, usually iron deficiency.
High MCHC: Rare; often due to laboratory artifact or cell dehydration rather than true pathology.
Interpretation combinations:
Low MCV + Low MCHC → Iron deficiency anemia.
High MCV + Normal MCHC → Regenerative or macrocytic anemia.
Normal MCV + Normal MCHC → Chronic disease or non-regenerative anemia.
These indices, combined with reticulocyte counts, reveal whether the bone marrow is actively responding to anemia.
Platelets (PLT), MPV, PDW, and PCT Evaluation in Dogs
Platelets (thrombocytes) play a vital role in blood clotting and wound repair. Their count and morphology reflect both hemostatic status and bone marrow activity.
Platelet Count (PLT)
Normal range: 150–500 ×10⁹/L
Thrombocytopenia (Low PLT): May result from immune-mediated destruction (IMT), viral disease, severe blood loss, or bone marrow suppression. Clinically, it leads to spontaneous bruising or bleeding.
Thrombocytosis (High PLT): Common in inflammation, iron deficiency, or post-splenectomy recovery.
Mean Platelet Volume (MPV)
MPV (normal 9–12 fL) measures the average platelet size.
High MPV: Indicates active platelet regeneration; young platelets are larger.
Low MPV: Suggests bone marrow suppression or decreased platelet production.
Platelet Distribution Width (PDW)
PDW (normal 10–18 fL) reflects variation in platelet size.
Increased PDW: Sign of active platelet turnover or destruction.
Decreased PDW: Homogeneous platelet population, usually less clinically significant.
Plateletcrit (PCT)
PCT represents the total platelet mass (normally 0.20–0.50%). It combines PLT and MPV data to estimate overall clotting capacity.
Low PCT: Indicates thrombocytopenia or blood loss.
High PCT: Suggests reactive thrombocytosis or inflammatory response.
A comprehensive evaluation of PLT, MPV, PDW, and PCT enables the clinician to differentiate between platelet destruction, consumption, and production disorders, which is crucial in diagnosing immune-mediated and inflammatory diseases in dogs.
Clinical Importance of NLR and PLR Ratios in Dogs
The Neutrophil-to-Lymphocyte Ratio (NLR) and Platelet-to-Lymphocyte Ratio (PLR) are emerging as valuable indicators of systemic inflammation and physiological stress in dogs. These ratios provide deeper insights into immune system dynamics than individual cell counts alone.
Neutrophil-to-Lymphocyte Ratio (NLR)
NLR is calculated by dividing the absolute neutrophil count by the lymphocyte count. In dogs, the normal range typically lies between 2 and 5.
NLR >5: Suggests acute stress, bacterial infection, sepsis, pancreatitis, pyometra, or systemic inflammatory response syndrome (SIRS).
NLR <2: Associated with viral infections, immune suppression, or lymphoid malignancies.
Because NLR is less affected by hydration status and corticosteroid therapy, it is considered a stable and reliable inflammatory marker in dogs. It can also serve as a prognostic indicator in severe infections, neoplasia, and metabolic diseases.
Platelet-to-Lymphocyte Ratio (PLR)
PLR is calculated by dividing the platelet count by the lymphocyte count. In healthy dogs, it generally ranges from 100 to 300.
High PLR (>300): Indicates chronic inflammation, oxidative stress, or tumor-associated immune response.
Low PLR (<100): May occur in viral infections or immune-mediated disorders where lymphocytosis predominates.
In clinical practice, both ratios are often used together.
High NLR + High PLR: Suggests severe systemic inflammation.
High NLR + Normal PLR: Indicates acute infection or corticosteroid effect.
Low NLR + Low PLR: Seen in viral or immunosuppressive conditions.
These ratios are cost-effective, rapidly measurable, and extremely useful in differentiating bacterial versus viral infections and evaluating disease prognosis in dogs.
Hemogram Changes in Anemia, Dehydration, and Infection in Dogs
Hemogram patterns shift significantly in response to physiological and pathological processes. Among the most common alterations are those related to anemia, dehydration, and infection.
Anemia
Anemia is defined by reduced RBC, HGB, and HCT levels.
Regenerative anemia: Caused by blood loss or hemolysis; characterized by increased reticulocyte counts.
Non-regenerative anemia: Due to chronic kidney disease, endocrine disorders, or bone marrow failure.
Microcytic, hypochromic anemia: Typical of iron deficiency.
Macrocytic anemia: Suggests active regeneration or vitamin B12/folate deficiency.
Pale mucous membranes, lethargy, and tachycardia are common clinical findings. Microscopic evaluation for spherocytes or Heinz bodies helps confirm hemolytic processes.
Dehydration
In dehydration, HCT, HGB, and RBC values appear artificially elevated due to plasma volume loss. Total protein and albumin levels often rise in parallel. Rehydration therapy typically normalizes these parameters within 24–48 hours.
Infection and Inflammation
Bacterial infections: Characterized by neutrophilia, left shift (presence of immature neutrophils), and monocytosis.
Viral infections: Usually cause lymphopenia or lymphocytosis depending on the stage of infection.
Parasitic infestations: Lead to eosinophilia (common in heartworm or intestinal parasite infections).
Chronic inflammatory diseases: Often show mild monocytosis and elevated PLR.
Interpreting these changes holistically allows veterinarians to differentiate between acute bacterial, chronic inflammatory, and viral conditions, providing valuable guidance for therapy and prognosis.
Reference Value Differences in Puppies, Senior Dogs, Pregnant Dogs, and Various Breeds
Hemogram reference intervals are not universal — they differ depending on age, breed, sex, reproductive status, and environmental factors. Interpreting blood results without accounting for these physiological variations can lead to diagnostic errors.
Puppies (Neonates and Juveniles)
In puppies, hematologic parameters differ markedly from adults due to immature bone marrow function and developing immune systems.
RBC, HGB, and HCT values are typically lower because erythropoiesis is not yet fully established.
MCV and MCH may be slightly higher (physiological macrocytosis).
WBC counts are often elevated due to lymphocyte predominance — a normal developmental finding.
Platelet counts (PLT) reach adult levels within a few weeks after birth.
Puppies are more susceptible to anemia caused by parasites (fleas, ticks, intestinal worms) and malnutrition, so species- and age-specific reference ranges must always be used.
Senior Dogs
Aging brings a gradual decline in hematopoietic activity and immune efficiency.
Mild decreases in RBC, HGB, and HCT are common.
WBC may increase slightly due to chronic low-grade inflammation (termed “inflamm-aging”).
PLT may decrease or MPV increase, reflecting reduced platelet function.Anemia of chronic disease and reduced erythropoietin production from renal insufficiency are frequent findings in geriatric dogs.
Pregnant Dogs
Physiological changes during pregnancy alter hemogram parameters substantially:
HCT and HGB decrease due to plasma volume expansion (hemodilution).
WBC increases, with neutrophil dominance.
PLT may decrease slightly but usually remains within the normal range.These shifts are normal and should not be mistaken for pathological anemia or infection unless accompanied by clinical symptoms.
Breed-Specific Differences
Certain breeds show unique hematologic traits that must be recognized during interpretation:
Greyhounds and Sighthounds: Naturally high RBC, HGB, and HCT due to superior oxygen-carrying capacity.
Akita and Shiba Inu: Physiological microcytosis (low MCV) without true anemia.
Cavalier King Charles Spaniels: Mild thrombocytopenia (low PLT) is common but non-pathological.
Poodles: Slight neutrophilia and elevated total protein levels are typical.
Veterinarians should always consult breed-adjusted reference intervals to prevent misclassification of normal physiological variations as disease.
Clinical Use of Hemogram Results in Veterinary Practice
The hemogram is one of the most valuable diagnostic tools in veterinary medicine, serving as a window into the dog’s systemic health. However, its interpretation must always be integrated with the clinical history, physical exam findings, and other laboratory data.
Diagnostic Applications
General screening: Detects hidden diseases before clinical signs emerge.
Preoperative evaluation: Identifies anemia, infection, or coagulation problems before anesthesia.
Monitoring chronic conditions: Tracks disease progression and therapeutic response in disorders like renal failure, endocrine diseases, or cancer.
Therapeutic Monitoring and Prognosis
Antibiotic therapy: A decreasing WBC and normalization of neutrophil count indicate recovery.
Anemia treatment: Rising HCT and reticulocyte count demonstrate bone marrow regeneration.
Cancer or inflammation: Reductions in NLR and PLR ratios reflect improved systemic inflammation.
Common Clinical Scenarios
Canine Parvovirus: Severe leukopenia and neutropenia.
Cushing’s Disease (Hyperadrenocorticism): Neutrophilia, lymphopenia, eosinopenia, and high NLR.
Heartworm Disease: Eosinophilia and monocytosis.
Iron Deficiency Anemia: Low HGB, HCT, MCV, and MCHC.
Acute Blood Loss: Low HCT with normal MCV and MCHC early on; regenerative response later.
Integrative Interpretation
A hemogram alone cannot provide a definitive diagnosis. When combined with biochemical panels, urinalysis, and clinical examination, it becomes a powerful indicator of systemic health and a guide for further diagnostics or therapy planning.
Frequently Asked Questions (FAQ)
What is a hemogram (CBC) in dogs?
A hemogram, or Complete Blood Count (CBC), measures the number and quality of red blood cells, white blood cells, and platelets in a dog’s blood. It helps evaluate oxygen transport, immune response, and clotting ability, offering crucial insight into the dog’s overall health.
Why is a CBC test important for dogs?
Because it provides early detection of infections, anemia, dehydration, and inflammatory or immune-mediated diseases. Veterinarians use it for screening, pre-surgical checks, and ongoing monitoring of chronic conditions.
How long does it take to get CBC results for dogs?
Most modern veterinary clinics can produce results within minutes. In-house hematology analyzers instantly process blood samples, allowing same-day diagnosis.
When should my dog have a hemogram test done?
A CBC is recommended if your dog shows lethargy, pale gums, weight loss, fever, or appetite loss. It’s also routine before surgery or anesthesia and during long-term drug therapy.
What does high white blood cell count (WBC) mean in dogs?
An elevated WBC count (leukocytosis) indicates bacterial infection, inflammation, stress, or corticosteroid administration. It may also occur in immune-mediated diseases or cancer.
What causes low white blood cell count in dogs?
Low WBC (leukopenia) can result from viral infections such as parvovirus, bone-marrow suppression, toxin exposure, or severe sepsis. It weakens the dog’s immune defense against pathogens.
What does low hematocrit (HCT) indicate?
A low HCT value signals anemia — caused by blood loss, hemolysis, or decreased production of red cells. Values below 30% typically warrant immediate investigation.
Why might a dog’s RBC count be high?
Commonly due to dehydration, which concentrates the blood. It can also be caused by chronic hypoxia (living at high altitude) or bone-marrow disorders like polycythemia vera.
Is low platelet count (thrombocytopenia) dangerous in dogs?
Yes. Thrombocytopenia increases the risk of spontaneous bleeding and bruising. Immune-mediated thrombocytopenia (IMT) is a common cause and requires urgent treatment.
What does high MPV mean on a dog’s CBC?
High MPV (Mean Platelet Volume) indicates that the bone marrow is producing larger, younger platelets — usually following blood loss or platelet destruction.
What are NLR and PLR ratios in dogs?
NLR (Neutrophil-to-Lymphocyte Ratio) and PLR (Platelet-to-Lymphocyte Ratio) are markers of systemic inflammation and stress. High ratios suggest infection, sepsis, or chronic inflammation.
What does a high NLR ratio suggest in dogs?
An NLR greater than 5 often reflects severe bacterial infection, trauma, or systemic inflammatory response syndrome (SIRS). It may also indicate physiological stress or corticosteroid influence.
What does PLR tell us about a dog’s health?
A high PLR (>300) usually signals chronic inflammation or neoplastic activity, while a low PLR (<100) may occur in viral infections or immune stimulation.
What are the signs of anemia in dogs?
Pale gums, fatigue, rapid breathing, cold extremities, and poor exercise tolerance. A CBC showing low RBC, HGB, and HCT confirms anemia.
Can anemia in dogs be treated?
Yes, but treatment depends on the cause. Iron supplementation helps with nutritional deficiency; transfusions are used for severe blood loss; and immune-mediated anemia requires corticosteroids or immunosuppressants.
What causes high eosinophil levels in dogs?
Eosinophilia commonly results from parasite infestations (heartworm, intestinal worms) or allergic conditions such as atopy or dermatitis.
What is lymphopenia in dogs?
Lymphopenia means reduced lymphocyte count, often due to stress, steroid medication, or viral suppression of bone-marrow function.
What is a stress leukogram in dogs?
A stress leukogram refers to a pattern of neutrophilia, lymphopenia, and eosinopenia caused by stress, corticosteroid therapy, or post-surgical conditions.
Do pregnant dogs show different CBC values?
Yes. Pregnancy causes hemodilution (lower HCT and HGB) and mild neutrophilia due to hormonal and physiological changes. These are normal adjustments.
Should dogs fast before a CBC test?
Ideally yes — fasting for 8–10 hours helps ensure plasma clarity and prevents post-prandial changes in certain parameters.
What is the significance of reticulocytes in a dog’s blood test?
Reticulocytes are immature red cells. An increased reticulocyte count shows the bone marrow is responding properly to anemia and producing new RBCs.
What factors can cause inaccurate CBC results?
Clotted samples, improper storage, delayed analysis, or mixing errors can all distort cell counts. Blood should be analyzed promptly after collection.
How often should a CBC be done for healthy dogs?
Once a year during routine wellness exams. Senior dogs or those with chronic illnesses should have it repeated every 3–6 months.
What’s the difference between CBC and biochemistry in dogs?
A CBC assesses blood cells, while biochemistry evaluates organ function (liver, kidney, glucose, electrolytes). Both are complementary diagnostic tools.
How should CBC results be interpreted in dogs?
Always in context — with the dog’s breed, age, medical history, and physical exam findings. Single parameters should never be evaluated in isolation.
Keywords
dog hemogram, complete blood count in dogs, canine CBC interpretation, anemia in dogs, dog blood test values
Sources
American College of Veterinary Internal Medicine (ACVIM)
Cornell University College of Veterinary Medicine
Merck Veterinary Manual
Clinical Pathology of Domestic Animals – Thrall et al.
Mersin Vetlife Veterinary Clinic – Map Link: https://share.google/XPP6L1V6c1EnGP3Oc
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