What is polycythemia vera in dogs and cats?

Polycythemia vera is a condition in which red blood cell numbers increase abnormally, which can cause thickened blood, circulatory problems, or bleeding irregularities. Diagnosis requires blood tests and imaging — consult your vet for further evaluation.

What warning signs can I watch for at home?

Common warning signs include persistent weakness, changes in appetite, increased drinking and urination, and abnormal vision or behaviour. Keep a record and bring it to the clinic for your vet's reference.

What tests are typically done at the clinic?

Common tests include a complete blood count (CBC), coagulation and biochemistry panels, radiographs or ultrasound, and sometimes echocardiography or bone marrow examination to identify the cause.

How often should my pet be rechecked after treatment?

Revisit frequency depends on your pet's condition. Blood values are typically rechecked within a few weeks initially, then adjusted to monthly or every few months based on stability — follow your vet's guidance.

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

Polycythemia Vera in Dogs & Cats: Weakness, Vision Changes & Blood Test Guide [2025]

Abnormal red blood cell proliferation requiring regular phlebotomy

Take 1 minute to check the symptoms first

Last updated: 2026/01/06

Pethealthmap Editorial Team

Sources: ACVIM, WSAVA, National Taiwan University Veterinary Hospital

When to See a Vet

Seek immediate veterinary care (emergency)

•Persistent inability to stand with extreme weakness and lethargy
•Vomiting blood, black stools, or obvious external bleeding
•Persistent seizures or clearly impaired consciousness

Schedule a veterinary appointment as soon as possible (within 24-72 hours)

•Significantly increased drinking and frequent urination
•Persistent decreased appetite or clearly reduced food intake
•Clearly reduced activity level and less willingness to interact

01What symptoms indicate a problem?

Common clinical signs of polycythemia vera in dogs and cats that owners can observe, helping with early detection and tracking of disease progression.

Persistent weakness or a significant drop in activity level
Reduced appetite or a noticeable change in food intake over a short period
Increased water consumption accompanied by changes in urination frequency
Blurred vision, bumping into objects, or sudden vision loss
Lethargy or reduced interest in interacting with people or other animals
Monitor for changes in mucous membrane colour (e.g. darker or deeply flushed gums)

Seek emergency care immediately if you notice the following symptoms:

⚠️ Seek immediate veterinary care if heavy bleeding or black tarry stools occur
⚠️ Go to an emergency clinic immediately if sudden vision loss or seizures develop

02How to assess concerns at home: key monitoring points and when to go to emergency

Important items to record at home to help your vet quickly assess disease progression and treatment response.

Log daily appetite and food intake changes, including feeding times
Track total daily water intake, urination frequency, and urine colour changes
Monitor fluctuations in energy level, willingness to jump, and play behaviour
Record short videos as visual evidence of vision problems or abnormal behaviour
Note when symptoms first appeared, how often they occur, and whether they are worsening
Bring all records and videos to the clinic for your vet's reference

03How does the vet diagnose this condition? Common diagnostic tests

Blood tests and imaging are typically used after arrival to identify the underlying cause and determine whether further workup or referral is needed.

Complete physical examination

assessing cardiovascular and pulmonary function, mucous membrane colour, and overall condition

Haematology (CBC)

measuring red blood cell count, haemoglobin, and packed cell volume (haematocrit)

Coagulation panel and biochemistry

evaluating liver, kidney, and metabolic status

Radiographs or abdominal ultrasound

ruling out thoracic or abdominal causes

Echocardiography or bone marrow examination when needed to clarify the underlying cause

04What comes after diagnosis? Treatment, diet adjustment, and home care guide

Regular follow-up tests and home monitoring are essential after treatment, and long-term management plans should be discussed with your vet.

Follow the vet's plan for prescribed tests, medications, or procedures and attend all scheduled appointments
Regular blood draws to monitor haemoglobin, red blood cell count, and packed cell volume
Adjust the treatment plan and revisit frequency based on test results
Continue monitoring at home for signs of bleeding, weakness, seizures, or vision changes
Discuss long-term monitoring frequency and quality-of-life adjustments (diet and activity) with your vet

05What to prepare before the vet visit: key information to help your vet reach a diagnosis quickly

Write down when symptoms started, how they have progressed, and how often they occur

Prepare a record of daily water intake and urination frequency over the past few days

List recent changes in appetite and all current medications or supplements

Capture photos or videos of important behavioural or vision abnormalities

Bring previous blood test results, imaging, or medical records if available

Ask the clinic to arrange necessary blood tests and imaging on arrival

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.