What are the early signs of carbon monoxide exposure in dogs and cats?

Early signs commonly include lethargy, reduced appetite, repeated vomiting, and rapid breathing — symptoms may appear within a few hours of exposure. If poisoning is suspected, seek veterinary care or advice promptly.

What tests will the vet typically run once my pet arrives at the clinic?

The vet will perform a physical examination, blood and blood gas tests, chest imaging, and cardiopulmonary monitoring. Further imaging or hospitalisation may be arranged depending on the severity.

What can I do at home while waiting to see the vet?

Record the time symptoms started, the number of vomiting episodes, and film your pet's breathing and general condition. Bring all records to the clinic or call your vet for guidance as soon as possible.

How long does recovery and follow-up usually take after carbon monoxide poisoning?

Prognosis depends on the severity of exposure. Mild cases may improve within a few days, while more severe cases may require hospitalisation for days to weeks. Follow your vet's schedule for check-ups and monitoring tests.

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

Carbon Monoxide Poisoning in Dogs & Cats: Symptoms, Diagnosis & Care Guide [2025]

Carbon monoxide poisoning is a medical emergency that can cause brain damage — move your pet to fresh air immediately and seek veterinary oxygen therapy.

Take 1 minute to check the symptoms first

Last updated: 2026/01/05

Pethealthmap Editorial Team

Sources: AVMA, Merck, National Taiwan University Veterinary Hospital

When to See a Vet

Seek emergency care immediately

•Obvious difficulty breathing or respiratory arrest
•Persistent unresponsiveness or prolonged deep coma
•Noticeably purple or pale lips or gums

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

•Significantly reduced appetite combined with markedly low activity level
•Repeated or frequent vomiting with no improvement
•Breathing faster than normal or showing obvious labored breathing

01What Symptoms Indicate Something Is Wrong?

Common clinical signs and warning indicators of carbon monoxide poisoning — severity can change rapidly, so close monitoring is essential.

Lethargy, drowsiness, or noticeable weakness
Repeated vomiting or frequent vomiting in a short period
Persistent coughing or signs of throat irritation
Rapid breathing or laboured breathing (dyspnoea)
Reduced activity levels and noticeably decreased appetite
If poisoning is suspected, seek a veterinary evaluation promptly

Seek emergency care immediately if you notice the following symptoms:

⚠️ Severe difficulty breathing or respiratory arrest
⚠️ Prolonged unresponsiveness or deep unconsciousness
⚠️ Obvious cyanosis (blue or purple discolouration) or pallor of the lips or gums

02How to Assess the Situation at Home: Key Observations and When to Go to the Emergency Vet

Keeping records and filming at home before the vet visit can help your veterinarian assess the situation quickly.

Note the time symptoms began and the order in which they appeared
Record the number of vomiting episodes, the times they occurred, and what the vomit looked like
Use your phone to film your pet's breathing from the side and close up
Observe any changes in appetite, water intake, and activity level
Track urination and defecation frequency, and note any abnormal colour or consistency
Bring all notes and photos to your appointment and seek veterinary care as soon as possible

03How Will the Vet Diagnose My Pet? Common Examination and Tests

The veterinarian will combine a physical examination with imaging and blood tests to assess the severity of poisoning and identify potential complications.

Physical examination

cardiopulmonary auscultation, mucous membrane colour, and neurological reflexes

Blood biochemistry and blood gas analysis to evaluate organ function and oxygenation status

Chest X-ray to assess the lungs and heart

Electrocardiogram (ECG) and vital sign monitoring to evaluate cardiopulmonary function

CT scan or advanced imaging if needed to evaluate complex cases

A specialist or emergency hospital with oxygen therapy and imaging equipment is recommended

04Treatment and Aftercare: Medications, Dietary Adjustments & Home Care Guide

Treatment focuses on restoring oxygenation and monitoring organ function, with appropriate hospitalisation or outpatient follow-up as required.

Immediate oxygen supplementation with close monitoring of vital signs and respiratory function
Hospitalisation may be arranged to monitor cardiac, pulmonary, and neurological function
Supportive therapy tailored to the patient's condition with ongoing blood parameter monitoring
At-home care: provide a quiet environment and ensure adequate rest
Regular follow-up appointments to monitor blood work and imaging changes
Specialist or emergency vet follow-up is recommended for ongoing assessment

05What to Prepare Before the Vet Visit: Key Information to Help the Vet Act Quickly

Write down the time symptoms began and how they progressed

Bring photos of any vomit or stool, along with your written records

List recent exposure history (location, heating appliances, etc.) and any relevant items

Prepare video footage of your pet's activity and breathing for the vet's reference

Transport your pet in a secure carrier and call ahead to schedule your 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)

Ataxia

Incoordination

Coma

Unconsciousness

Cough

Forceful air expulsion from airways

Lethargy

Decreased activity

Dyspnea

Difficulty breathing

Hypotension

Low blood pressure