Confused by your animal’s lab results? This guide breaks down some of the most common blood tests your veterinarian may perform, helping you interpret those numbers and notations. While you might not always see a copy of your pet’s lab results, understanding them can be empowering.
Defining “Normal” in Lab Results
It’s crucial to understand what “normal” signifies in laboratory testing. Each lab establishes its own set of normal values based on its patient population. Furthermore, a pet can sometimes present with results that appear abnormal yet indicate a perfectly healthy individual. This is because normal values are typically determined using a bell-shaped curve, where approximately 90% of healthy patients fall within the central range. This means that 5% of normal pets might have results falling below the lower end of the normal range, and another 5% might have results above the higher end.
For instance, consider the Blood Urea Nitrogen (BUN) test, commonly used to assess kidney function. For most labs, normal BUN values range from 10 to 30. This implies that 90% of healthy dogs will have a BUN within this range. However, 5% of healthy dogs might exhibit a BUN below 10, and 5% above 30. If your dog’s BUN is 40, which is outside the typical normal range, your veterinarian’s expertise is essential in determining if this is indeed normal for your pet or a potential indicator of serious kidney disease. Factors like previous test results, trends over time, and other related kidney function tests (such as creatinine and urinalysis) are considered. If previous results were consistently around 40, it might simply be your dog’s normal. Repeating the test in one to two weeks and monitoring other kidney function indicators can provide further clarity. For senior dogs, where kidney disease is more prevalent, regular monitoring is especially important.
Common Blood Tests Explained
Kidney Function
Blood Urea Nitrogen (BUN): While a common indicator of kidney function, BUN can also be influenced by factors like intestinal bleeding and dietary protein. In kidney disease, BUN levels tend to rise gradually. Mild elevations, as mentioned, might be normal if other kidney function tests are within normal limits. Therefore, an isolated elevated BUN may not be clinically significant but can be a crucial alert when considered alongside other diagnostic markers.
Creatinine: This test is a more sensitive indicator of kidney dysfunction. Even minor increases in creatinine levels can suggest significant kidney problems. As it is less affected by dietary protein than BUN, any elevation in creatinine should raise a strong suspicion of underlying kidney disease.
Urinalysis: A urinalysis provides a wealth of information, including the urine specific gravity, which is vital for assessing kidney function. Healthy kidneys can efficiently dilute or concentrate water from the bloodstream to produce urine. When kidney function declines, this ability is compromised, leading to an abnormal specific gravity. Similar to blood tests, a single abnormal specific gravity reading might not be conclusive. However, repeated abnormalities, especially when coupled with abnormal blood kidney test results, can signal a kidney problem.
Diabetes
Diabetes, though less common in dogs than in humans, is a serious condition. It’s typically diagnosed through laboratory tests and observable clinical signs. The blood glucose test is a primary diagnostic tool. While stress can elevate blood glucose levels, persistently high levels often strongly suggest diabetes. A urinalysis also aids in diagnosis. Normally, dogs do not excrete glucose in their urine. However, as blood glucose rises, some glucose “spills” into the urine. In severe cases, such as diabetic ketoacidosis, glucose levels are very high, as are levels of ketones, a type of fatty acid. Combining blood profile results with urinalysis helps veterinarians diagnose diabetes. In ambiguous cases, a fructosamine blood test can be performed. Elevated fructosamine levels indicate persistently high blood glucose levels, distinguishing diabetes from temporary stress-induced hyperglycemia.
Liver Function
True liver disease is relatively uncommon in most dogs. The alanine transaminase (ALT) test is the primary diagnostic tool for liver disease. When the liver experiences trauma, infection, inflammation, or cancer, cells are damaged, causing ALT to leak into the bloodstream, resulting in elevated ALT levels. Minor elevations can be considered normal, particularly in older dogs or those on certain medications like corticosteroids or phenobarbital. Elevated ALT levels indicate that something is affecting the liver, but they don’t specify the exact cause, which could range from infection and inflammation to benign or cancerous lesions.
Adrenal Function
The overproduction of adrenal hormones, especially cortisol, is a frequent issue in older dogs. An elevated alkaline phosphatase (ALP) value often points to excess cortisol, either from overactive adrenal glands or from corticosteroid medications. While ALP can also be elevated in liver disease, its most common cause in dogs is adrenal disease, particularly when other liver tests are normal. A frequent diagnostic error is misdiagnosing adrenal disease as liver disease based solely on an elevated ALP level. There are no conventional medications specifically for elevated ALP, but certain herbs and homeopathics may help slow the progression of Cushing’s disease, a condition resulting from excessive cortisol production.
Conclusion
Regular laboratory testing is essential for your dog’s health, helping to establish baseline normal values and enabling early detection and treatment of potentially life-threatening diseases. Remember, even results that appear “abnormal” might be perfectly normal for your individual pet. If there are any doubts, repeating the test or seeking a second opinion can alleviate concerns. Understanding these common tests empowers you to have more informed discussions with your veterinarian about your pet’s well-being.
