How is Pneumocystis pneumonia diagnosed?

Diagnosis typically involves physical examination, chest imaging, and PCR or cytology testing of sputum or bronchoalveolar lavage samples to confirm the pathogen and assess lung damage.

How long does treatment usually take before improvement is seen?

Time to clinical improvement varies between individual pets and disease severity. Some pets show improvement within a few weeks, but a complete treatment course may take weeks to months — follow-up as directed by your vet.

Can this type of pneumonia spread to other pets or people?

Some pathogens carry a risk of transmission; whether infection spreads depends on the specific organism and the immune status of the animals involved. If you have concerns, discuss preventive measures with your vet.

What information should the owner bring to follow-up appointments?

Bring video clips of coughing or wheezing episodes, a log of your pet's weight and temperature, a current medication list, and any previous imaging or test reports so your vet can compare and evaluate progress.

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

Pneumocystis Pneumonia in Dogs & Cats: Symptoms, PCR Diagnosis & Long-Term Care [2025]

A rare fungal pneumonia seen in immunocompromised pets

Take 1 minute to check the symptoms first

Last updated: 2026/01/06

Pethealthmap Editorial Team

Sources: ACVIM, AVMA, National Taiwan University Veterinary Hospital

When to See a Vet

Seek immediate emergency care

•Obvious open-mouth breathing that cannot be calmed down
•Noticeably purple or discolored gums or tongue
•Sudden lethargy, unresponsiveness, or inability to move

Schedule a clinic visit soon (within 24–72 hours)

•Persistent or worsening cough that occurs frequently
•Breathing noticeably faster and more labored than usual
•Significant loss of appetite with continued weight loss

01What symptoms indicate something is wrong?

Pneumocystis pneumonia primarily presents with respiratory and systemic signs. Early stages may be subtle; as the disease progresses, breathing and energy levels become noticeably affected.

Gradual weight loss, reduced appetite or lower food intake
Intermittent or persistent fever, lethargy and decreased activity
Dry or productive cough, increasing in frequency
Rapid breathing, laboured breathing or open-mouth panting
Darkening or bluish discolouration of the lips or gums (suspected hypoxia)

Seek emergency care immediately if you notice the following symptoms:

⚠️ Severe breathing difficulty or persistent open-mouth panting
⚠️ Obvious purple or blue discolouration of the gums or tongue
⚠️ Sudden marked drop in alertness, extreme lethargy or unresponsiveness

02How can you assess the situation at home? Key observations and emergency criteria

Monitoring and recording your pet's breathing and general condition at home can help your vet shorten the diagnostic process and assess disease progression.

Weigh your pet at the same time each day and record the results
Take your pet's temperature morning and evening and log the readings
Record short video clips of coughing or wheezing episodes (front and side views)
Observe and note breathing rate and whether breathing appears effortful
If abnormalities persist or worsen, arrange a veterinary visit as soon as possible

03How will the vet make a diagnosis? Common diagnostic tests

Your vet will combine clinical examination with laboratory and imaging tests to confirm the pathogen and assess the degree of lung involvement.

Physical examination

auscultation of the lungs, assessment of breathing and vital signs

Blood tests

evaluation of inflammatory markers and organ function

Cytology or tissue biopsy (if needed) to characterise lesions

Sputum or bronchoalveolar lavage samples sent for PCR or culture to identify the pathogen

Chest X-ray or CT scan to evaluate pulmonary imaging abnormalities

Referral to an infectious disease or specialist centre recommended for complex cases

04What treatment and care are needed after diagnosis? Medications, diet and home care guide

Pneumocystis pneumonia typically requires long-term medication and regular monitoring. Home care and side-effect surveillance are equally important.

Treatment courses are often prolonged; regular follow-up visits are required to monitor response
Schedule periodic blood tests and imaging as recommended by your vet
Provide adequate calories and fluids to maintain nutritional support
Allow your pet to rest quietly; avoid respiratory irritants and strenuous exercise
Observe and record any discomfort or side effects that arise during treatment
Arrange ongoing follow-up with an infectious disease specialist or referral centre if needed

05What should you prepare before the vet visit? Keys to helping your vet identify the cause quickly

Record short video clips of coughing or wheezing (front and side views) to assist observation

Note when symptoms started, how they have changed, and any signs of improvement or deterioration

Measure and write down your pet's most recent weight and temperature readings

List all current medications, supplements and vaccination history

Prepare a secure carrier and call ahead to book a specialist or clinic appointment

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.

Related Symptoms (You May Also Be Looking For)

Elevated temperature

Bluish discoloration

Difficulty breathing

Reduced exercise capacity

Anorexia

Loss of appetite

Tachypnea

Rapid breathing