By Russel J Leadsom BVSc CertVC MRCVS
Signalment and history
A 9-year-old male crossbred dog presented with a recent history of exercise-induced syncope. Heart rate alternated between 130 bpm and 65 bpm, both with regular rhythms.
Echocardiography was unremarkable.
- Intermittent second-degree 2:1 AV block with concurrent left bundle branch block.
- The blocked P waves are indicated *.
- The arrhythmia deteriorated to second-degree 2:1 AV block with periods of advanced 3:1 block, and increased frequency of syncopal episodes.
- There was no response to atropine, and a pacemaker was fitted.
- To date this dog has a healthy active life.