Signalment, clinical signs, and prognostic indicators associated with high-grade second- or third-degree atrioventricular block in dogs: 124 cases (January 1, 1997-December 31, 1997).
OBJECTIVE
To evaluate signalment, clinical signs, and prognosis associated with high-grade second- or third-degree atrioventricular block (AVB) in dogs.


METHODS
Retrospective case series.


METHODS
124 dogs.


METHODS
Data were gathered from ECGs, veterinarian questionnaires, echocardiograms, and radiographs submitted for review; compared with data from a large control group; and examined for association between variables and duration of survival. A new classification system for AVB was evaluated.


RESULTS
Afghan, Catahoula Leopard Dog, Chow Chow, Cocker Spaniel, German Wirehaired Pointer, and Labrador Retriever breeds were predisposed to high-grade second- or third-degree AVB. Heavier, older, and sexually intact female dogs were overrepresented in the study group. Weakness, lethargy, exercise intolerance, and syncope were the most common clinical signs. The presence of clinical signs was not associated with duration of survival. Dogs with high-grade second-degree AVB had a duration of survival similar to that of dogs with third-degree AVB. Dogs with high-grade second- or third-degree AVB were at high risk for sudden death in the first 6 months after diagnosis. High ventricular escape rhythm rate and narrow escape-complex QRS width were negatively associated with duration of survival. Pacemaker implantation had a significant positive association with survival.


CONCLUSIONS
Pacemaker implantation should be strongly considered in all dogs with high-grade second- or third-degree AVB regardless of whether clinical signs are evident. If medical treatment is warranted, vagolytic medications may be the best choice. A new classification system for AVB may merit further investigation.
Schrope
Donald P
DP
Oradell Animal Hospital, 580 Winters Avenue, Paramus, NJ 07652, USA.
Kelch
William J
WJ
D000367:Age Factors; D000818:Animals; D001835:Body Weight / Q000502:physiology; D001947:Breeding; D003645:Death, Sudden / Q000209:etiology / Q000662:veterinary; D004283:Dog Diseases / Q000145:classification / Q000401:mortality / Q000473:pathology*; D004285:Dogs; D004562:Electrocardiography / Q000379:methods / Q000662:veterinary; D005260:Female; D006327:Heart Block / Q000145:classification / Q000401:mortality / Q000473:pathology / Q000662:veterinary*; D008297:Male; D010138:Pacemaker, Artificial / Q000662:veterinary*; D011379:Prognosis; D012189:Retrospective Studies; D012720:Severity of Illness Index; D012737:Sex Factors; D016019:Survival Analysis