Establishing 24-hour Holter reference intervals for clinically healthy puppies

Area of Science:

• Veterinary Cardiology
• Canine Electrophysiology

Background:

• Normal Holter reference intervals are not established for dogs under one year of age.
• This data gap hinders early screening for cardiac arrhythmias in puppies, particularly in predisposed breeds like German Shepherds and Boxers.

Purpose of the Study:

• To establish Holter minimum, average, and maximum heart rates for healthy puppies (<1 year).
• To determine the incidence of arrhythmias in healthy puppies.
• To compare puppy Holter data with existing adult dog data.

Main Methods:

• Prospective study of 44 client-owned, healthy puppies (12-51 weeks old).
• Age confirmed by birth records and dental examination.
• 24-hour Holter (ECG) recordings were obtained; echocardiography was performed for murmurs.

Main Results:

• Median Holter heart rates: Minimum 51 bpm, Average 99 bpm, Maximum 274 bpm.
• Arrhythmias: 9% ventricular premature complexes, 13% supraventricular premature complexes, 5% second-degree AV block.
• Puppies exhibited higher minimum, average, and maximum heart rates than adult dogs.

Conclusions:

• Established reference ranges for puppy Holter heart rates and common arrhythmias.
• Puppy heart rates are significantly higher than adult dogs.
• The incidence of premature complexes in puppies is comparable to adult dogs, suggesting Holter monitoring is valuable for young dogs.