Electrocardiographic monitoring in normal and abnormal pregnant dogs

P.G. BLANCO; P.R. BATISTA; M. TÓRTORA; R. RODRÍGUEZ; D.O. ARIAS; C. GOBELLO

Sevilla

Congreso; 21st Congress of the European College of Veterinary Internal Medicine ? Companion Animals; 2011

ECVIM-CA

Canine cardiac conduction system might be modified by anatomical and functional adaptations of maternal heart to gestation. The aim of this study was to describe dog electrocardiographic features during normal and abnormal pregnancy. Thirty-three Brucellosis-negative pregnant bitches were retrospectively classified as normal (n = 12) or abnormal (n = 11). A control group of non-pregnant dioestrous female dogs (n = 10) was also included. Normal pregnant animals delivered healthy puppies at term while abnormal bitches interrupted their pregnancy between days 52 to 60 (from luteinizing hormone peak) or presented perinatal litter death higher than 60%. All the dogs were electrocardiographically evaluated every ten days from day 0 to day 65 of the estrous cycle, to parturition or abortion. Percentage heart rate change increased 31.3% from day 40 to 60 in normal gestation while it decreased -1.8% in dioestrous bitches, and it did not change in the abnormal group (P < 0.01). In the abnormal pregnant group but not in the others, percentage QRSa change fell to -34% on day 60 (P < 0.01). At the same time point, percentage QRSd change was 6.2% vs. -4.9% in normal gestations and dioestrous animals, respectively (P < 0.05). Corrected QT interval augmented from day 40 onwards up to 9.9% and 4.3% in the normal pregnant and dioestrous females, respectively. Conversely, this parameter remained unchanged in abnormal bitches (P < 0.05). In this study, cardiovascular dissimilarities between normal and abnormal pregnant bitches preceded the appearance of complications. For this reason, the use of electrocardiography in canine obstetrics might contribute to identify pathologycal outcomes before they become clinically evident. It is concluded that during normal canine pregnancy, some electrochardiographic parameters begin to change from day 40 onwards, while abnormal gestations began to electrochardiographically differ from normality from day 30 onwards. Therefore, monitoring the maternal electrocardiogram during pregnancy might be important to support medical decision making in canine obstetrics.