Bradycardia-associated syncope in 7 Boxers with ventricular tachycardia (2002-2005)

Area of Science:

• Veterinary Cardiology
• Canine Medicine

Background:

• Syncope is a common issue in Boxers, often linked to rapid ventricular tachycardia (VT).
• While dilated cardiomyopathy may be present, echocardiograms are frequently normal in affected dogs.
• Neurocardiogenic bradycardia is another potential cause of syncope in this breed.

Observation:

• This study focused on seven Boxer dogs with both documented VT and neurocardiogenic bradycardia.
• These dogs were selected from a larger group of Boxers with Holter-documented VT.
• The syncopal episodes in these selected dogs were attributed to bradycardia rather than VT.

Findings:

• All seven Boxers had Holter-documented VT.
• However, the syncopal episodes were consistently attributed to neurocardiogenic bradycardia.
• This indicates that bradycardia was the primary cause of syncope in these cases.

Implications:

• In Boxers, neurocardiogenic bradycardia and VT can occur independently or concurrently.
• When both conditions coexist, syncope may be primarily due to bradycardia.
• Treatments like beta-blockers or sotalol can worsen or trigger syncope related to neurocardiogenic bradycardia in these dogs.