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High White Blood Cell Count in Dogs: What It Means

If your dog's bloodwork shows a high white blood cell count, it's natural to worry. White blood cells (WBCs) are part of the immune system and help fight infection and inflammation. This guide explains what a high WBC means, possible causes, and what your vet may recommend next.

A high white blood cell count (above 17,000-20,000/μL) in dogs usually indicates the body is fighting infection, inflammation, or stress, and requires diagnostic testing to determine the underlying cause.

What Is a White Blood Cell Count?

A white blood cell count is part of a complete blood count (CBC). It measures the number of white blood cells circulating in your dog's blood. These cells are the body's primary defense against infections, inflammation, and foreign substances.

Normal White Blood Cell Range in Dogs:

  1. Normal WBC: 6,000–17,000 cells per microliter (μL)
  2. High WBC (Leukocytosis): Above 17,000-20,000/μL
  3. Note: Ranges may vary slightly between laboratories
  4. Age factor: Puppies may have slightly different normal ranges

Types of White Blood Cells

Understanding which type of white blood cell is elevated can help determine the cause:

  1. Neutrophils: Fight bacterial infections (most common type)
  2. Lymphocytes: Handle viral infections and immune responses
  3. Monocytes: Clean up debris and fight certain infections
  4. Eosinophils: Respond to allergies and parasites
  5. Basophils: Involved in allergic reactions (least common)

Causes of High White Blood Cell Counts in Dogs

A high WBC count (leukocytosis) often means the body is responding to a problem, such as:

Infections:

  1. Bacterial infections (skin, urinary tract, respiratory)
  2. Viral infections
  3. Fungal infections
  4. Tick-borne diseases (Rocky Mountain Spotted Fever, Ehrlichiosis)
  5. Parasitic infections

Inflammation:

  1. Pancreatitis
  2. Autoimmune diseases
  3. Severe allergic reactions
  4. Inflammatory bowel disease
  5. Tissue damage or trauma

Other Causes:

  1. Stress response (exercise, excitement, heat)
  2. Steroid use (like prednisone)
  3. Blood cancers (leukemia, lymphoma)
  4. Certain medications

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Symptoms That May Accompany High WBC

Some dogs show no outward symptoms, and the change is only found on bloodwork. When symptoms do occur, they may include:

  1. Fever
  2. Lethargy or decreased energy
  3. Loss of appetite
  4. Swollen lymph nodes
  5. Vomiting or diarrhea (with infections or inflammation)
  6. Difficulty breathing (with respiratory infections)
  7. Changes in urination (with urinary tract infections)

How Vets Diagnose the Cause

Your vet may recommend additional tests to pinpoint why WBC is high:

Common Follow-up Tests:

  1. Blood smear: Microscopic examination to look at WBC types and shapes
  2. Chemistry panel: Check organ function (liver, kidneys)
  3. Infectious disease tests: Tick panels, cultures, or specific disease tests
  4. Imaging: X-rays or ultrasound if internal disease is suspected
  5. Urinalysis: Check for urinary tract infections
  6. Fine needle aspirate: Sample lymph nodes or masses if present

Treatment and Outlook

Treatment depends on the underlying cause:

Treatment Options:

  1. Infections: Antibiotics, antifungals, or antiparasitic medications
  2. Autoimmune diseases: Steroids or immunosuppressive drugs
  3. Inflammation: Anti-inflammatory medications and supportive care
  4. Cancer: Specialist referral for oncology evaluation
  5. Stress-related: Often resolves without specific treatment

Many causes of high WBC are very treatable once identified. The key is determining the underlying cause through appropriate diagnostic testing.

When to Be Concerned

Contact Your Vet If:

  1. Your dog shows signs of illness (fever, lethargy, loss of appetite)
  2. WBC count is extremely high (over 30,000/μL)
  3. Other blood values are also abnormal
  4. Your dog has a history of cancer or immune system problems
  5. Symptoms worsen or don't improve with treatment

Monitoring and Follow-Up

  1. Follow-up bloodwork is often needed to monitor treatment response
  2. Some conditions require regular CBC monitoring
  3. Keep track of any symptoms or changes in your dog's behavior
  4. Complete prescribed treatments even if your dog seems better

Related Reading

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Frequently Asked Questions

Is a high white blood cell count always serious?

Not necessarily. It can range from stress-related temporary elevations to more serious conditions like infections or cancer. The key is identifying the underlying cause through proper testing.

How quickly can white blood cell counts change?

WBC counts can change rapidly - sometimes within hours to days. This is why your vet may recommend repeat bloodwork to monitor treatment response or track changes.

Can stress really cause high white blood cell counts?

Yes, physical or emotional stress, excitement, exercise, and even the stress of a vet visit can temporarily elevate white blood cell counts in some dogs.

What's the difference between high and low white blood cell counts?

High counts usually indicate the body is actively fighting something (infection, inflammation). Low counts may suggest the immune system is suppressed or overwhelmed, which can be more concerning.