We investigated 613 cases of ECG in beagle dogs at 6 to 20 months of age, which are the animals usually employed in general toxicity studies. T wave patterns in the present examples were examined and discussed from the point of toxicity evaluation. Incidence was 52.3, 34.2, and 13.5% for the positive, negative, and biphasic waves, respectively, with the incidence of the positive wave exceeding 50% in animals at 6 months of age. However, the incidence of positive waves decreased to 33.3–36.7% and that of negative waves increased to 50.0–60.0% at the age of 7–10 months, and negative waves showed a tendency to further increase gradually thereafter. T wave pattern also changes in accordance with posture or induction method employed, and therefore it is essential for T wave data to be evaluated in conjunction with other data such as clinical chemistry.

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Clinical pathology, electrocardiography (ECG), and echocardiography (ultrasonocardiography; UCG) were studied from nineteen dogs with heartworm infection. These dogs were classified as class 1 or 2 dirofilariasis. Their conditions were monitored by the following tests: hematology, blood biochemistry, ECG and UCG. ECG measurements included six limb leads and UCG values were obtained from two-dimensional (2D), M-mode, and spectral Doppler (pulsed-wave and continuous wave) examinations. The findings of the present study were summarized as follows. Over 2/3 of the dogs with mild dirofilaliasis had eosinophilia (68.4%). Although thrombocytopenia (36.4%) and increased ALT activities (15.8%) were not as common, they were still noticeable. In the findings of ECG, some dogs in the present study had deep Q and S waves, and high R and P waves. In M-mode UCG observation, some tested dogs had increasing LV ejection phases indices, i.e. EPSS (29.4%), LVFS (17.6%), and LVPWFT (11.6%). There were some dogs with increases of M-mode derived systolic time intervals, i.e. PEP (52.9%), PEP/LVET ratio (35.3%), and QAVC (23.5%). In some dogs, indices of Doppler evaluation of diastolic function also increased, i.e. MV PHT (23.5%) and DT (17.6%). Furthermore, there were dogs with increases of systolic time intervals and pressure recordings of pulmonary flow measured by Doppler UCG, i.e. PV VTI (17.6%), PV ET (17.6%) and MnGrad (11.8%). In conclusion, class 1 and 2 heartworm-infected dogs showed no or only mild clinical signs, however, their cardiopulmonary function and some clinical pathologic parameters may have been altered. Realization of these alterations is essential to adapt the therapeutic program, to decide upon conditions of treatment, and to objectively evaluate clinical improvement after the treatment.

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[in Japanese]

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[in Japanese]

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Two cases of atresia of the left atrioventricular orifice with situs solitus of atria were observed in Japanese Black calves. The atresia of the orifice was derived from atresia of the left atrioventricular valve in one case and absence of the left atrioventricular connection in another, respectively. Both cases revealed the right atrium connected to the morphological left ventricle and concordant ventriculoarterial connection.

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