Atrial fibrillation in dogs with and without structural or functional cardiac disease: A retrospective study of 109 cases.

Objectives: To determine if the heart rate and survival of dogs with atrial fibrillation (AF) varied amongst those: (1) without structural and functional disease (Group NoDz), (2) with structural or functional disease without pulmonary edema or ascites (Group DzNoF), and (3) with structural or functional disease with pulmonary edema or ascites (Group DzF).

Animals, Materials And Methods: The records of 109 dogs from the Veterinary Teaching Hospital of the University of Montreal (n=30) and the Cornell University Hospital for Animals (n=79) were examined.

Results: Large and giant breed dogs were most commonly affected (95.5%) with the Irish Wolfhound, Mastiff, Newfoundland, and Rottweiler overrepresented (P<0.01) in Group NoDz and the Irish Wolfhound, Boxer, English Sheepdog, Great Dane and Doberman Pincher overrepresented (P<0.01) in Groups DzNoF and DzF. Males (73.4%) were more commonly affected (P<0.001). Heart rate (mean+/-SD) on presentation was different amongst the 3 groups of dogs (P<0.001) (Group NoDz: 120+/-8.0bpm, Group DzNoF: 155+/-7.6bpm, and Group DzF: 203+/-6.2bpm). Kaplan-Meier survival analysis revealed a longer survival for dogs in Group NoDz (P=0.006) and large and giant breeds (P=0.02). Initial heart rate could not be separated from diseased group as an independent determinant of survival.

Conclusions: Results suggest that dogs with AF and no demonstrable cardiac disease have a slower presenting heart rate and greater survival than dogs with structural disease with and without heart failure.