Holter’s monitoring and electrocardiogram (ECG) both record the heart’s electrical activity. However, unlike a standard ECG, the Holter’s monitor can continuously record the pet’s heart’s electrical activity for an extended period (24-48 hours). In contrast, a standard ECG is generally used to record the heart’s electrical activity for a few minutes.

Both are used to diagnose arrhythmias (irregular heartbeats, slow or fast heartbeats), which can lead to symptoms such as fatigue, fainting, and shortness of breath in pets.

The reason veterinarians would recommend Holter monitoring: 

When pet owners take their dogs or cats to the animal hospital, it can be an extremely stressful experience for the pets. Due to anxiety, the veterinarian may not be able to capture the pet’s accurate heart activity within the short duration of a standard ECG.

Moreover, arrhythmias often occur suddenly and transiently, and they might not manifest during a hospital visit.

Additionally, arrhythmias can sometimes be triggered by certain factors, such as after vigorous exercise or a change in posture.

Therefore, having the pet wear a Holter’s monitor at home allows for the accurate recording of their “real condition” in a familiar environment.