Does leukocytosis mean there is an infection?

A raised white blood cell count is commonly seen with infection or inflammation, but it can also be related to stress or other underlying conditions. Further blood work and diagnostic tests are needed to determine the cause — consult your vet.

What tests does a vet usually run to find the cause?

Common tests include a complete blood count (CBC), blood biochemistry panel, urinalysis, and when indicated, imaging or culture tests to identify the source of infection or inflammation.

How often does my pet need blood tests for follow-up?

The frequency of follow-up blood tests depends on your pet's condition. Initially, testing may be done every few days to once a week; once the condition stabilises, retesting is typically scheduled every few weeks or as advised by your vet.

What can I do at home to help my pet recover?

At home, ensure your pet gets plenty of rest, encourage water intake, monitor and record appetite and elimination changes, and bring your pet back for scheduled follow-up visits as directed by your vet.

How much do the tests and treatment usually cost?

Costs vary by clinic and region — ask your vet for an estimate before proceeding.

Disease Guide

Leukocytosis in Dogs & Cats: Symptoms, Blood Tests & Care Guide [2025]

Leukocytosis refers to an abnormally elevated white blood cell count in the blood, typically signalling infection or inflammation that requires identifying the underlying cause.

Take 1 minute to check the symptoms first

Last updated: 2026/01/05

Pethealthmap Editorial Team

Sources: AVMA, WSAVA, National Taiwan University Veterinary Hospital

When to See a Vet

Seek Emergency Care Immediately

•Persistent high fever for more than 24 hours accompanied by lethargy
•Noticeably rapid breathing or open-mouth breathing
•Sudden collapse or significantly reduced level of consciousness

Schedule a Clinic Visit Soon (within 24–72 hours)

•Noticeably reduced appetite or continued refusal to eat in a short period
•Persistent low-grade fever or intermittent fever lasting more than two days
•Simultaneous decline in alertness and activity level that does not improve

01What Symptoms Signal a Problem?

The common clinical signs of leukocytosis are often related to systemic infection or inflammation. Below are symptoms owners can watch for, along with important warning signs.

Persistent or recurring fever with body temperature above normal
Reduced appetite, obvious refusal to eat, or decreased food intake
Lethargy and noticeably reduced activity level
Noticeable weight loss or wasting over a short period
Changes in elimination habits such as diarrhoea, bloody stool, or abnormal urine output
Seek veterinary evaluation promptly if symptoms persist or worsen

Seek emergency care immediately if you notice the following symptoms:

⚠️ Persistent high fever lasting more than 24 hours with a depressed mental state
⚠️ Obvious rapid breathing or open-mouth breathing
⚠️ Sudden collapse or significantly reduced responsiveness

02How to Assess Abnormalities at Home: Key Observations & Emergency Criteria

Observing and recording key information at home helps your vet quickly understand the condition and prioritise diagnostic steps.

Record daily food intake, meal times, and any refusal to eat
Weigh your pet weekly or regularly during illness and track weight changes
Use a thermometer to measure and record body temperature if fever is suspected
Monitor mental alertness, sleep patterns, and changes in activity level
Note frequency and character of urination and defecation, including blood or mucus
Take short videos or photos of symptoms to share with your vet at the appointment

03How Does a Vet Diagnose This? Common Diagnostic Tests

Your vet will use a physical examination along with laboratory and imaging tests to identify the source of inflammation or infection and determine whether other systemic diseases are involved.

Complete blood count (CBC)

assesses white blood cell numbers and differential changes

Blood biochemistry panel

evaluates liver and kidney function, and electrolyte abnormalities

Urinalysis

screens for urinary tract infection or kidney issues

X-ray or ultrasound

examines thoracic and abdominal organs and checks for deep-seated lesions

Bacterial culture or PCR

identifies the causative pathogen to guide treatment

04Post-Diagnosis Treatment & Care: Medications, Diet Adjustments & Home Care Guide

Treatment depends on the underlying cause and often requires short- to long-term monitoring of blood values and clinical signs. Home care after discharge is equally important.

Targeted or symptomatic treatment and supportive care based on the identified cause
Severe cases may require hospitalisation, fluid therapy, and intensive supportive care
Follow up as directed after discharge with scheduled blood tests to monitor white cell counts and biochemistry
Adjust diet and record appetite and weight changes to assess recovery progress
Key home care priorities: adequate rest, maintaining hydration, and keeping all follow-up appointments
Referral to a specialist or diagnostic centre may be arranged by your vet if needed

05What to Prepare Before the Vet Visit: Key Information to Help Your Vet Quickly Identify the Cause

Record when symptoms started, how they have progressed, and any possible triggers

Note recent appetite, water intake, and toileting records

Bring a list of current medications or supplements and your pet's feeding routine

Prepare short videos or photos to help the vet observe behaviour and symptoms

Bring originals or copies of any past test reports or imaging results

Call ahead to book an appointment and choose a clinic with in-house diagnostic capabilities

This content is for reference only and cannot replace a professional veterinary diagnosis. If your pet shows signs of illness, please seek veterinary care promptly.