🐕 Understanding Blood Work in Pets: What Each Value Means
When your vet says, “We’ll need to run some blood work,” it can feel overwhelming. Blood tests are one of the most powerful tools veterinarians use to assess your pet’s internal health. But what do those confusing numbers really mean?
This complete guide will help you understand every common value found in your pet’s blood report — from CBCs to chemistry panels, thyroid markers to electrolytes. With expert input, scientific sources, and summary charts, you’ll know exactly what to look for and when to act.
🔮 Why Blood Work Matters for Pets
Routine blood tests help:
- Detect early signs of disease (kidney, liver, infection)
- Monitor chronic conditions
- Check organ function before surgery
- Guide medication doses
- Provide baseline data for senior pets
“Blood work is a window into your pet’s organs. It helps us find problems before symptoms start.” — Dr. Emily Meadows, DVM
🦚 Common Types of Blood Tests in Pets
| Test | What It Evaluates |
|---|---|
| CBC (Complete Blood Count) | Red/white blood cells, platelets |
| Chemistry Panel | Kidney, liver, pancreas, protein, glucose |
| Electrolyte Panel | Sodium, potassium, chloride, calcium |
| Thyroid (T4, fT4) | Thyroid gland function (common in cats/dogs) |
| SDMA | Early kidney function detection |
| Heartworm/Tick Tests | Vector-borne disease status |
🦉 Understanding CBC: Complete Blood Count
1. Red Blood Cells (RBC, HCT, HGB)
- Function: Carry oxygen from lungs to tissues
- Low? May suggest anemia, bleeding, or chronic disease
- High? Could mean dehydration or polycythemia
2. White Blood Cells (WBC)
- Function: Fight infection & inflammation
- High? Indicates infection, inflammation, or stress
- Low? May reflect immune suppression or viral infections
3. Platelets (PLT)
- Function: Help blood clot
- Low? Risk of bleeding (e.g., tick-borne disease)
- High? May signal inflammation, anemia, or bone marrow issue
4. MCV, MCH, MCHC
- Provide details about RBC size and hemoglobin content
- Help classify types of anemia
🌟 Blood Chemistry Panel Explained
1. BUN (Blood Urea Nitrogen) & Creatinine
- Indicate: Kidney function
- High? Kidney disease or dehydration
- Low? Liver disease or overhydration
📈 SDMA is more sensitive than creatinine for early kidney disease (Source)
2. ALT (Alanine Aminotransferase)
- Indicates: Liver cell health
- High? Liver damage or inflammation
3. ALP (Alkaline Phosphatase)
- Function: Liver and bone enzyme
- High? Cholestasis, bone growth, or steroid use
4. Total Protein (TP), Albumin, Globulin
- High or low? Suggests liver/kidney disease, inflammation, or malnutrition
5. Glucose (GLU)
- Low? Hypoglycemia (especially dangerous in small dogs/cats)
- High? Diabetes, stress
6. Amylase, Lipase
- Role: Pancreatic enzymes
- High? Possible pancreatitis
⚡ Electrolyte Values
| Electrolyte | Normal Function | Abnormal Values May Indicate |
| Sodium (Na) | Fluid balance, nerve function | Dehydration, Addison’s, kidney issues |
| Potassium (K) | Muscle & heart function | Kidney disease, GI loss, Addison’s |
| Chloride (Cl) | Acid-base balance | Vomiting, metabolic alkalosis |
| Calcium (Ca) | Bone, muscle, nerve regulation | Cancer, kidney failure, parathyroid disease |
🤢 Thyroid Function Tests (Common in Seniors)
T4 (Total Thyroxine)
- Low T4: Hypothyroidism (dogs)
- High T4: Hyperthyroidism (cats)
Hyperthyroidism is one of the most common hormonal diseases in senior cats. Cornell Feline Health Center
🥦 Interpreting the Full Picture: Not Just One Value
Veterinarians never interpret one value alone.
“We always look at trends, combinations, and your pet’s clinical signs. A single high value doesn’t always mean disease.” — Dr. Karen Louis, Internal Medicine Specialist, DACVIM
Example:
- High BUN + normal creatinine = dehydration
- Low RBC + high MCV = regenerative anemia
- High glucose + stress = transient rise (not diabetes)
📊 Sample Summary Table: Key Blood Test Values
| Test | Normal Range (Dogs) | Normal Range (Cats) | High May Indicate | Low May Indicate |
| RBC | 5.5-8.5 x10^6/µL | 5.0-10 x10^6/µL | Dehydration, bone marrow issue | Anemia, bleeding |
| WBC | 6.0-17.0 x10^3/µL | 5.5-19.5 x10^3/µL | Infection, inflammation | Viral disease, immune suppression |
| ALT | 10-125 U/L | 20-100 U/L | Liver damage | Rarely low |
| Creatinine | 0.5-1.5 mg/dL | 0.8-2.4 mg/dL | Kidney dysfunction | Overhydration, liver dysfunction |
(Always refer to your vet for lab-specific reference ranges)
🎓 Expert Quote Section
“Blood work is the foundation of preventive care. Even young pets can hide illness that only blood tests reveal.” — Dr. Michael Kaufman, VMD
Source: American Veterinary Medical Association
“We often detect early kidney disease or diabetes in pets during routine pre-surgical blood work. Owners are shocked their pet showed no signs.” — Dr. Lisa Radosta, DVM, DACVB
🔍 Step-by-Step: What to Do After a Blood Test
- ✅ Get a printed copy of your pet’s blood report.
- ❓ Ask your vet to explain each abnormal value.
- ✍️ Track trends over time if your pet has ongoing issues.
- 📊 Follow vet advice for further testing, diet, or treatment.
- 📱 Consider uploading results to a pet health app for history tracking.
📆 When to Re-Test?
| Scenario | Suggested Retest Window |
| Mild elevations with no symptoms | 2-4 weeks |
| Monitoring chronic illness | Every 3-6 months |
| Before anesthesia | Within 30 days of surgery |
| Senior wellness screening | Every 6-12 months |
🧵 FAQs About Pet Blood Work
1. How often should my pet get blood work?
At least annually for healthy adults, and every 6 months for seniors or pets with chronic conditions.
2. Can blood work detect cancer in pets?
It can reveal signs suggestive of cancer (like abnormal WBCs), but imaging or biopsy is often needed to confirm.
3. What does a high ALT level mean in dogs?
It suggests liver stress or damage. Your vet may recommend a liver ultrasound or further liver function tests.
4. Are blood tests safe for small dogs and cats?
Yes, modern testing uses very small volumes, even for puppies or kittens.
5. How quickly are blood test results available?
In-house labs may provide results within 30 minutes; external labs usually take 1–2 days.
6. Does my pet need to fast before blood work?
Yes, 8–12 hours fasting is ideal, especially for glucose and lipid panels.
7. Why did my pet’s bloodwork come back “borderline”?
Values slightly out of range may be normal depending on breed, age, hydration, or stress. Your vet will assess context.
🔲 Final Thoughts
Understanding your pet’s blood work doesn’t have to be scary. With guidance from your veterinarian and knowledge of what each value means, you can stay ahead of disease and give your pet the healthiest life possible.
⚠️ Disclaimer
This guide is for educational purposes only and does not replace veterinary diagnosis. Always consult your vet to interpret blood test results and make decisions about your pet’s health.
