Some forms of heart disease affect the heart structurally, while other forms of heart disease can affect the heart’s electrical system. In some cases, both structure and electrical activity are affected.

Echocardiograms allow us to evaluate heart size and function, whereas electrocardiograms (ECGs) measure the heart’s electrical activity. The spread of electricity through the heart muscle is what signals the heart muscle to pump, so impairment to the electrical system can affect heart function.

At Massachusetts Veterinary Referral Hospital, ECG monitoring plays a critical role in both emergency stabilization and long-term cardiac management.

What Is an ECG?

An electrocardiogram records the electrical activity of the heart. Small clips or electrodes are placed on the skin to detect electrical impulses moving through the heart muscle. The machine transmits these impulses to paper as a tracing, which is then interpreted by the cardiologist.

An ECG allows cardiologists to:

• Identify abnormal heart rhythms (arrhythmias)

• Detect irregular conduction patterns

• Measure heart rate, particularly in cases where listening with a stethoscope may be less accurate

This test is non-invasive and typically completed within minutes.

When Is ECG Monitoring Recommended?

Your primary veterinarian or our emergency or cardiology team may recommend ECG evaluation when:

• An abnormal heart rhythm is detected during examination

• A pet experiences episodes of weakness or collapse

• There are unexplained changes in heart rate

• A patient is being stabilized during an emergency

• Monitoring is needed during or prior to anesthesia

In critical care situations, continuous ECG monitoring may be recommended to ensure immediate recognition of rhythm changes and assess for intermittent arrhythmia. For continuous monitoring, adhesive electrodes are applied to the animal’s chest and held in place with a padded wrap or vest, which is worn throughout hospitalization.

“Electrical disturbances can be linked to structural heart disease, but they can also occur even when the heart’s structure appears normal on echocardiogram,” says Dr. Elizabeth Wiley, DVM, DACVIM, Veterinary Cardiologist at Massachusetts Veterinary Referral Hospital. “ECG testing allows us to further characterize abnormal heart rhythms and assess whether intervention is necessary, as some arrhythmias require treatment, whereas others do not.”

Short-Term vs. Extended Monitoring

Not all rhythm disturbances are constant. Some occur intermittently. In these cases, an ECG that takes place over a few minutes may not be sufficient to fully evaluate the arrhythmia, and more extended monitoring may be recommended.

Depending on the case, your pet may undergo:

• Short-term rhythm assessment (an ECG is performed, lasting a few minutes)

• In-hospital continuous ECG monitoring (a monitor is worn by the patient during hospitalization for real-time rhythm assessment, usually for hours or days)

• At-home Holter monitor (a monitor is placed by the cardiology team and worn at home by the patient, usually for 24 hours, then returned for interpretation)

Extended monitoring helps us capture arrhythmia that may not appear during a brief examination, which allows us to determine more accurately whether additional intervention is necessary.

Why Early Detection Matters

Some forms of arrhythmia can affect blood circulation and oxygen delivery, which can lead to organ dysfunction and compromise patient stability. In severe cases, some arrhythmias can put patients at risk of fainting (syncope) or sudden death. Early identification allows us to reduce patient risk by:

• Initiating appropriate medication

• Adjusting existing cardiac therapy

• Determining whether advanced intervention is needed

• Coordinating care with other specialties, including Emergency and Critical Care

At Massachusetts Veterinary Referral Hospital, cardiology works seamlessly alongside all our specialty services, including Emergency & Critical Care. When an unstable pet arrives, ECG monitoring often begins immediately through the emergency service, with cardiology consultation available if the need is identified.

Calm, Focused Cardiac Care

Heart-related concerns can be urgent and frightening for pet parents. Our cardiology team prioritizes timely, thoughtful evaluation and clear communication.

ECG and Holter monitoring are some of several advanced diagnostic tools that allow us to create a treatment plan tailored to your pet’s individual needs.

If a veterinarian recommends ECG or Holter evaluation, it is because detailed rhythm assessment provides essential information for safe, effective care.

Massachusetts Veterinary Referral Hospital Cardiology & 24-Hour Emergency Care in Woburn, MA

Expert Care When It Matters Most