What can cause supraventricular tachycardia in dogs and cats?

Supraventricular tachycardia may be linked to structural heart changes, metabolic abnormalities, or other systemic diseases. A vet needs to run tests such as an ECG, ultrasound, and blood tests to look for possible causes, so ask your vet about further assessment.

How does a vet confirm whether my pet has an arrhythmia?

The vet will use a physical examination together with an electrocardiogram (ECG) and echocardiography to assess heart rhythm and heart function. If needed, a 24-hour Holter monitor may be arranged to observe episodes, and the next steps will be discussed based on the results.

If I notice brief fainting or an irregular heartbeat, how soon should my pet see a vet?

Seek veterinary care immediately if your pet has repeated or prolonged fainting, obvious breathing difficulty, or altered consciousness. For other signs such as brief fainting or frequent coughing, arrange a consultation within 24-72 hours and bring episode records or videos for your vet to review.

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

Supraventricular Tachycardia in Dogs and Cats: Weakness, Fainting, Heart Rhythm Tests & Care [2025]

A fast heart rhythm starting above the ventricles that may need medication to control the heart rate.

Take 1 minute to check the symptoms first

Last updated: 2025/01/06

Pethealthmap Editorial Team

Sources: ACVIM, AAHA, National Taiwan University Veterinary Hospital

When to See a Vet

Seek immediate veterinary care (emergency)

•Repeated or prolonged fainting with inability to recover
•Rapid breathing that clearly does not settle
•Complete loss of responsiveness or inability to be awakened

Schedule a clinic visit as soon as possible (within 24-72 hours)

•Brief fainting with quick return of consciousness but changes in behavior
•Persistent or repeated dry cough with frequent coughing
•Clearly reduced activity level but still able to eat on their own

01What symptoms suggest something is wrong?

In dogs and cats, supraventricular tachycardia often appears as non-specific signs such as reduced activity or fainting caused by an abnormal heart rhythm.

Sudden weakness or a clear drop in activity level
Repeated or persistent dry coughing that is more noticeable than usual
Brief fainting or suddenly collapsing needs special attention
You may notice a fast heartbeat, irregular rhythm, or palpitations
A new or changed heart murmur may be heard during auscultation

Seek emergency care immediately if you notice the following symptoms:

⚠️ Repeated or prolonged fainting needs immediate veterinary care
⚠️ Laboured breathing or rapid breathing should be treated as an emergency
⚠️ Unable to wake up or completely unresponsive

02How can you assess abnormalities at home? Key observations and emergency warning signs

Recording key changes at home can help your vet assess severity and identify the pattern of episodes.

Record how often coughing episodes happen, when they occur, and how long they last
Watch daily changes in mood and activity level, and note the time
Track daily appetite and water intake to see whether they change
Record urination, bowel movements, and body weight changes to assess overall condition
Take a phone video of an episode and mark the time it occurred
If fainting occurs, note what happened before and after it and how long it lasted
Bring these records to a cardiology appointment so the vet can review them

03How will the vet diagnose it? Common tests

At the clinic, the vet will start with a physical examination and use ECG and imaging tests to look for possible causes.

A complete physical examination, including heart and lung auscultation and vital sign assessment

Electrocardiogram (ECG) to assess heart rhythm and abnormal conduction patterns

Echocardiography to evaluate heart structure and cardiac function

Chest X-rays, or CT when needed, to assess the lungs and heart on imaging

Blood tests and biochemistry to rule out metabolic or electrolyte abnormalities

A 24-hour ECG monitor (Holter) may be arranged when needed to observe episodes

A hospital with echocardiography and ECG expertise is recommended

04How is it treated and managed after diagnosis? Medication, diet changes, and care guide

After diagnosis, treatment usually involves medication management, regular monitoring, and lifestyle adjustments to reduce the risk of recurrence.

Start or adjust heart rhythm control medication as recommended by the vet, and monitor the response
Return for regular check-ups and arrange ECG or echocardiography follow-up to track changes
At home, avoid strenuous exercise and emotional excitement that can increase cardiac workload
Diet and weight control can reduce strain on the heart and improve the outlook
Owners can monitor heart rate and symptom changes at home and keep records
Referral to a cardiology specialist hospital may be needed for further assessment and treatment

05What should you prepare before seeing the vet? Key details that help identify the cause

Prepare a timeline of symptoms, episode frequency, and possible triggers

List all current medications, supplements, and the dosing schedule

Bring videos of coughing or fainting episodes and note the time they occurred

Prepare recent blood test, imaging, or other test reports if available

Record recent changes in diet, drinking, urination, and bowel movements for the vet

Use a secure carrier and book with the clinic in advance to reduce waiting time

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.