| Most common routine panels | CBC + Chemistry Panel |
| Fasting required for bloodwork? | Often yes (8–12 hours), but confirm with your vet |
| Turnaround time (in-house labs) | 30–60 minutes for most panels |
| Turnaround time (reference labs) | Typically 24–72 hours |
| Recommended frequency for senior pets | Every 6–12 months (varies by species and condition) |
| Species note | Reference ranges differ between dogs, cats, and other species |
Why Vets Order Bloodwork
When your vet recommends bloodwork, it can feel alarming — or at least confusing. But lab tests are one of the most powerful tools in veterinary medicine precisely because animals can't tell us where it hurts. A blood panel gives your vet a window into organ function, immune activity, and metabolic health that no physical exam alone can provide.
Bloodwork is ordered in several common situations: routine wellness screening, pre-anesthetic evaluation before surgery, monitoring a known condition such as diabetes or kidney disease, or investigating new symptoms like lethargy or weight loss. Understanding why a test is ordered — and what it's looking for — makes the results far less intimidating. See our guide to wellness exams vs. sick visits to learn how these tests fit into different types of vet appointments.
| Most common routine panels | CBC + Chemistry Panel |
| Fasting required for bloodwork? | Often yes (8–12 hours), but confirm with your vet |
| Turnaround time (in-house labs) | 30–60 minutes for most panels |
| Turnaround time (reference labs) | Typically 24–72 hours |
| Recommended frequency for senior pets | Every 6–12 months (varies by species and condition) |
| Species note | Reference ranges differ between dogs, cats, and other species |
The Complete Blood Count (CBC): Your Pet's Blood Cells Under the Microscope
The CBC measures the three major types of blood cells and is often the first panel a vet reviews.
CBC (Complete Blood Count)
A blood test that measures the quantity and characteristics of red blood cells, white blood cells, and platelets. It helps vets detect anemia, infection, immune disorders, and clotting problems.
Chemistry Panel
A group of blood tests that measures enzymes, proteins, and waste products to evaluate organ function, especially the liver and kidneys. Also called a metabolic panel or blood chemistry.
ALT (Alanine Aminotransferase)
A liver enzyme that rises in the blood when liver cells are damaged or inflamed. Elevated ALT is one of the most common early indicators of liver stress in dogs and cats.
BUN (Blood Urea Nitrogen)
A waste product filtered by the kidneys. Elevated BUN can indicate reduced kidney function, dehydration, or high protein metabolism, and is typically evaluated alongside creatinine.
Hematocrit
The percentage of blood volume made up of red blood cells. Low hematocrit signals anemia; high hematocrit may indicate dehydration or, rarely, a red blood cell disorder.
SDMA (Symmetric Dimethylarginine)
A kidney biomarker detectable in the blood that may indicate reduced kidney function earlier than traditional markers like creatinine. Increasingly included in senior pet wellness panels.
T4 (Thyroxine)
The primary thyroid hormone measured in blood to screen for thyroid disease. Low T4 suggests hypothyroidism in dogs; high T4 is a key indicator of hyperthyroidism in cats.
Differential (WBC Differential)
A breakdown of the white blood cell count into its specific cell types, such as neutrophils, lymphocytes, and eosinophils. The pattern helps vets identify whether an immune response is due to infection, allergy, inflammation, or other causes.
- Red Blood Cells (RBC) & Hematocrit: Low values may indicate anemia; high values can suggest dehydration. Your vet will look at the size and shape of red cells too, which can point to nutritional deficiencies or bone marrow issues.
- White Blood Cells (WBC): Elevated counts often suggest infection, inflammation, or stress. Very low counts may indicate immune suppression or certain viral diseases. The differential — which breaks WBCs into subtypes like neutrophils and lymphocytes — helps narrow the cause.
- Platelets: These tiny cells are critical for clotting. Low platelet counts (thrombocytopenia) can explain unexplained bruising or prolonged bleeding and may require urgent follow-up.
A single abnormal CBC value rarely tells the whole story. Your vet interprets each result alongside the physical exam and your pet's history.
Chemistry Panels: A Snapshot of Organ Health
The chemistry panel (also called a metabolic panel or blood chemistry) evaluates the concentrations of enzymes, proteins, electrolytes, and waste products in the blood. Together, these numbers paint a picture of how well your pet's key organs are functioning.
Here are the markers vets examine most closely:
- BUN & Creatinine: Kidney function markers. Elevated levels can indicate reduced kidney filtration, dehydration, or protein breakdown. Vets often evaluate these alongside urine specific gravity for a fuller picture.
- ALT & ALP: Liver enzymes. Elevated ALT often signals active liver cell damage, while elevated ALP may point to liver, bone, or adrenal issues. Mild elevations are sometimes benign; large or persistent elevations warrant further investigation.
- Glucose: High blood sugar may suggest diabetes mellitus; low glucose can cause seizures or collapse and is a veterinary emergency.
- Total Protein & Albumin: Help evaluate hydration, liver production, and gut absorption. Low albumin specifically can cause fluid accumulation in the abdomen or chest.
- Electrolytes (Sodium, Potassium, Chloride): Imbalances can result from vomiting, diarrhea, kidney disease, or hormonal disorders like Addison's disease.
Ask your vet which specific markers were flagged and what follow-up testing, if any, is recommended.
~75%
Kidney function lost before creatinine rises
Veterinary internists estimate that creatinine may not become elevated until a significant portion of kidney function is already reduced, highlighting why early screening markers like SDMA matter.
1 in 10
Cats estimated to have hyperthyroidism over age 10
Hyperthyroidism is considered one of the most commonly diagnosed hormonal disorders in middle-aged and older cats in North America, making routine T4 testing valuable for senior feline wellness exams.
Thyroid, Urinalysis, and Other Common Add-Ons
Depending on your pet's age, species, and symptoms, your vet may recommend additional tests beyond the standard CBC and chemistry panel.
- Thyroid Hormone (T4): Hypothyroidism is common in dogs and can cause weight gain, lethargy, and coat changes. Hyperthyroidism is one of the most frequent diagnoses in middle-aged to older cats and can masquerade as simple aging. A total T4 (thyroxine) level is the standard starting point.
- Urinalysis: Urine concentration, pH, protein, glucose, and cell content together reveal kidney function, bladder health, and early signs of infection or diabetes. It's most informative when paired with bloodwork.
- SDMA: A newer kidney biomarker that may detect decline earlier than creatinine alone. Many panels now include it as a standard feature, especially for senior pets.
- Fecal Testing: While not bloodwork, a fecal exam checks for intestinal parasites and is an important part of the overall wellness picture.
Nutrition also intersects with lab results in meaningful ways — for example, low protein levels or certain mineral imbalances can reflect dietary gaps. Our guide to reading pet food labels explains how to evaluate what your pet is actually eating.
This article is for general informational purposes only and is not a substitute for professional veterinary advice. Always consult your veterinarian about your specific pet's health and lab results.