Clinical Pathology: Understanding Bloodwork, Urinalysis, and Interpreting Test Results

As veterinarians, we are trained to assess animals from various angles—through physical examination, history taking, and diagnostic testing. Among the most valuable tools at our disposal are the laboratory tests that provide insight into the internal workings of an animal's body. Clinical pathology, encompassing bloodwork, urinalysis, and the interpretation of these test results, plays a critical role in diagnosing illnesses, monitoring chronic conditions, and assessing overall health. For veterinary professionals, a solid understanding of clinical pathology is essential to provide comprehensive care to our patients.

At VetPro Expo, we aim to empower veterinary professionals by delving into the importance of clinical pathology, the processes involved in obtaining and interpreting results, and how these insights can guide effective treatment plans. In this blog post, we will explore how bloodwork and urinalysis can help reveal underlying health issues, how to interpret test results with accuracy, and how a thorough understanding of clinical pathology can improve patient care.

The Importance of Clinical Pathology in Veterinary Medicine

Clinical pathology is the branch of veterinary medicine that focuses on understanding the physiological and biochemical changes in an animal’s body. It involves analyzing biological samples, such as blood, urine, and other bodily fluids, to diagnose diseases, monitor treatment progress, and evaluate the overall health status of an animal.

Lab tests can help veterinarians:

Diagnose conditions early: Many diseases and health conditions show no obvious symptoms in the early stages. Blood and urine tests can provide vital clues before clinical signs develop.
Monitor ongoing conditions: Chronic conditions such as diabetes, kidney disease, and liver disorders require regular monitoring. Clinical pathology provides an objective means to track the progression of these diseases.
Assess organ function: Tests like liver enzymes, kidney markers, and electrolyte levels give insight into the function of essential organs.
Evaluate the body’s response to treatment: Bloodwork and urinalysis are crucial for determining whether a treatment is working and if any adjustments are needed.

Accurate interpretation of clinical pathology results is crucial in making informed decisions and formulating appropriate treatment plans.

Bloodwork: A Key Diagnostic Tool

Bloodwork is one of the most frequently performed laboratory tests in veterinary practice. A standard blood test typically includes a Complete Blood Count (CBC) and a Biochemical Profile (Chem Panel). These tests provide information about the cellular components of the blood and the levels of various biochemical markers that reflect organ function and overall health.

Complete Blood Count (CBC)

The CBC measures the concentration of red blood cells, white blood cells, and platelets in the blood. It helps identify conditions like anemia, infections, and blood clotting disorders. A CBC typically includes the following components:

Red Blood Cells (RBCs): RBC count is essential for diagnosing anemia (a low RBC count) or polycythemia (an abnormally high RBC count).
Hemoglobin (Hgb): The protein in red blood cells that carries oxygen. Low levels can indicate anemia or insufficient oxygen delivery to tissues.
Hematocrit (HCT): The percentage of blood volume made up of RBCs. A decrease in HCT can indicate anemia, while an increase could suggest dehydration or polycythemia.
White Blood Cells (WBCs): WBCs are part of the immune system. A high WBC count (leukocytosis) may indicate an infection, inflammation, or immune response. A low count (leukopenia) can suggest bone marrow disorders or viral infections.
Platelets: These are essential for blood clotting. Low platelet counts (thrombocytopenia) may lead to bleeding disorders, while high counts (thrombocytosis) can be associated with inflammation or certain types of cancer.

By evaluating the CBC, veterinarians can identify early signs of infection, anemia, inflammation, and other hematologic abnormalities.

Biochemical Profile (Chem Panel)

The biochemical profile provides a snapshot of the animal’s internal organ function, metabolic processes, and electrolyte balance. It typically includes tests for the following:

Liver Enzymes: Liver function is assessed using enzymes like ALT (alanine aminotransferase), AST (aspartate aminotransferase), ALP (alkaline phosphatase), and bilirubin levels. Elevated levels can indicate liver damage, hepatitis, or cholestasis.
Kidney Function: Blood urea nitrogen (BUN) and creatinine are key markers of kidney function. Elevated levels can indicate kidney disease, dehydration, or urinary obstruction.
Electrolytes: Sodium, potassium, chloride, and calcium levels help assess hydration status, kidney function, and metabolic abnormalities.
Protein Levels: Total protein, albumin, and globulin levels give insight into the body’s nutritional status and liver function. Abnormal levels can suggest liver disease, kidney disease, or nutritional deficiencies.
Glucose: Blood sugar levels are used to diagnose conditions such as diabetes mellitus and hypoglycemia. Elevated glucose levels may indicate diabetes, while low glucose levels could be due to insulin overdose or liver failure.

By analysing these markers, veterinarians can identify dysfunction in organs such as the liver, kidneys, and pancreas, providing vital information for diagnosis and treatment.

Urinalysis: Insights into Kidney and Metabolic Health

Urinalysis is another essential diagnostic tool that offers valuable insight into an animal’s metabolic health and kidney function. Urine analysis typically involves three key components: physical examination, chemical analysis, and microscopic examination.

Physical Examination

The color, clarity, and specific gravity of urine can provide important clues about an animal’s hydration status and potential underlying issues:

Color: Normal urine should be light yellow. Dark yellow or amber urine may indicate dehydration, while very pale urine could suggest excessive water intake or kidney problems.
Clarity: Cloudy urine may indicate the presence of cells, bacteria, or crystals, which could point to infections or urinary tract disease.
Specific Gravity: This measures the urine’s concentration and is important for assessing kidney function. A low specific gravity may suggest the kidneys are not concentrating urine effectively, a sign of renal failure.

Chemical Analysis

Urine dipsticks are used to assess various chemical properties of the urine:

pH: The acidity or alkalinity of urine can indicate metabolic imbalances or urinary tract issues. Alkaline urine may be seen with infections or certain kidney conditions.
Protein: The presence of protein in the urine can indicate kidney disease, particularly glomerular disease.
Glucose: Glucose in the urine (glucosuria) often suggests uncontrolled diabetes mellitus, as the kidneys excrete excess glucose when blood levels are too high.
Ketones: Ketones in the urine are commonly seen in diabetic ketoacidosis (DKA) or when an animal is fasting or in a state of starvation.
Bilirubin: Bilirubin in the urine can indicate liver disease or hemolysis, where red blood cells break down too quickly.
Blood: The presence of blood in the urine can suggest urinary tract infection, bladder stones, or trauma.

Microscopic Examination

A thorough urinalysis includes looking at the urine under a microscope to identify cells, bacteria, crystals, and casts. Common findings include:

Bacteria: Presence of bacteria can indicate a urinary tract infection.
Crystals: Different types of crystals may form in the urine depending on the pH and the presence of certain substances. For example, struvite crystals are often seen in urinary tract infections, while calcium oxalate crystals may indicate kidney stones.
Red Blood Cells (RBCs): A small number of RBCs in urine can be normal, but an increased number may indicate bleeding from the urinary tract due to infection, trauma, or stones.
White Blood Cells (WBCs): The presence of WBCs in urine may suggest an infection or inflammation in the urinary tract.

By analysing these components of urine, veterinarians can assess kidney function, detect infections, and identify metabolic disorders.

Interpreting Test Results: A Holistic Approach

When interpreting bloodwork and urinalysis results, it’s crucial to consider the patient as a whole—its clinical history, physical exam findings, and any presenting symptoms. Is the patient showing signs of lethargy, vomiting, or weight loss? Are there any chronic conditions that may affect the results, such as diabetes or kidney disease?

Understanding the normal reference ranges for various blood and urine parameters is essential for interpreting results accurately. These ranges can vary by species, age, sex, and even laboratory methods, so familiarity with these benchmarks is critical.

Furthermore, abnormal test results do not always indicate disease. Many factors, such as stress, medications, or sample collection errors, can affect test outcomes. It’s important to evaluate the results in context and, when necessary, follow up with additional tests to confirm a diagnosis.

Conclusion: The Power of Clinical Pathology in Veterinary Practice

Bloodwork, urinalysis, and the careful interpretation of these test results form the backbone of modern veterinary diagnostics. As veterinary professionals, a strong grasp of clinical pathology helps us identify underlying health conditions, guide treatment plans, and provide proactive care for our patients. By understanding how to interpret these tests accurately, we can ensure that our diagnoses are precise, and that our treatments are effective.

At VetPro Expo, we encourage veterinary professionals to continually expand their knowledge and stay up to date with the latest advances in clinical pathology. With a commitment to lifelong learning, we can deliver the best possible care to our patients, improving outcomes and enhancing their quality of life.