Electrocardiographic abnormalities in an English bulldog with amitraz toxicity

A 4-month-old female English bulldog was admitted to the clinic suffering with confusion after being found on the floor by a client. The clinical signs started a few hours after the dog was bathed with amitraz by the owner at home. Initial examinations revealed that the dog was recumbent and had signs of depression. Cardiac auscultation revealed a heart rate of 80 bpm. No heart murmur or obvious arrhythmia was auscultable. Electrocardiogram (ECG) revealed a regular sinus rhythm with a heart rate of approximately 80 bpm; however, the QT intervals were prolonged. The rate-corrected QT interval was calculated about 0. 29 s. Over the course of 3 h of supportive treatment and surface rewarming, the dog's general condition and temperature slightly improved, but the dog was still lethargic and recumbent. The ECG became normal with normal sinus rhythm and QT interval. In view of this information we suggest that clinicians use ECG in combination with other clinical data during the assessment of dogs with amitraz toxicity. © Springer-Verlag London Limited 2009.