The Rhode Island Red (RIR) shows a significantly higher incidence of spontaneously occurring arrhythmia due to atrial and ventricular premature depolarization compared with other breeds of chickens as evidenced by our previous study. It has been reported that arrhythmia develops from vitamin B₁ (thiamine) deficiency in various animals and that RIR is more susceptible to thiamine deficiency than other breeds of chickens. This study was therefore carried out to investigate the relationship between the higher incidence of arrhythmia in RIR and the higher susceptibility of RIR to thiamine deficiency. Thirty young RIR and 30 young White Leghorns (WL), aged 30 days after hatching, were used for experiments in the study. For both the RIR and the WL, one group consisting of 20 chicks was raised on thiamine-deficient rations as a special diet and another consisting of 10 chicks as normal controls was raised on a conventional diet containing sufficient thiamine; thus the chicks were divided into 4 groups for this experiment. Electrocardiographic examinations were performed during the observation period of 17 day to investigate the occurrence of arrhythmia. In contrast with the findings that the control RIR and WL exhibited stable heart rates of approximately 450/min and neither arrhythmia nor alternated ECG amplitude, electrocardiographic abnormalities were noted in both the groups of VB₁-deficient RIR and WL. Moreover, the heart rate tended to decrease gradually during the course of the study in both VB₁-deficient groups. Five types of arrhythmia were observed in RIR (8 cases) and WL (4 cases) as follows : sinus bradycardia (RIR : 2 ; WL : 3), sinoatrial exit block (1 ; 0), sinus arrest (3 ; 0), sinus arrhythmia (2 ; 1) . In addition, ECGs showing alternated amplitudes were observed in RIR (6 cases) and WL (6 cases) as follows : T wave abnormality (5 ; 3), elevation and depression of S-T segments (1 ; 3) . The VB₁-deficient groups showed significantly higher percentages of occurrence of arrhythmia and alternated EGG amplitude (p<0.001) . There was no significant difference in the percentage of occurrence or arrhythmia and/or alternated ECG amplitude between the two VB₁-deficient groups.
In conclusion, it seems unlikey that the higher incidence of arrhythmia in RIR found in our previous study is directly related to their higher sensitivity to VB₁ deficiency.

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In order to clarify the characteristics of the ultrasound pulsed Doppler waveforms in dogs, we measured the blood flow Doppler waveforms at the inflow tracts of the right and left ventricle in 35 clinically healthy mongrel dogs with a age of 2 years or less. Seven measurements were performed for the inflow tract and three measurements for the outflow tract. The values were then processed, and a composite waveform was obtained. The results showed that the blood flow velocity waveform of the left ventricular inflow tract is M-shaped, and that the early diastolic peak, peak 1, is always higher than the late diastolic peak, peak 2.
The blood flow velocity waveform of the left ventricular outflow tract was halfway between a V-shape and the shape of a check mark (∨), and the peak was located in the early systole. The blood flow velocity waveform of the right ventricular inflow tract was M-shaped, but both the wave height of peaks 1 and 2 and the differences between their height of peaks were small, and the waveform peak inversion rate was 40%. The blood flow velocity waveform of the right ventricular outflow tract was V-shaped. Its peak was located between early and mid-systole. These findings demonstrated that the characteristics of the Doppler waveforms in dogs are basically as the same as in humans.

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A multi-center field study to assess the safety and efficacy of enalapril maleate (enalapril) in household dogs with naturally acquired Class III or Class IV heart failure caused mainly by mitral regurgitation was conducted at 20 animal hospitals in Japan. One hundred and thirty-six dogs of various breeds and each sex, aged 5 to 18 years and weighing 1.4 to 19.7 kg were included in the study and were randomly allocated to a vehicle control group (control group) or to an enalapril treatment group (enalapril group). Dogs in the enalapril group received the medication at the starting dose of approximately 0.25 mg/kg once a day (s.i.d.) for 7 days, followed by 0.5 mg/kg s.i.d., with an option to increase the dose on Day 14 to 0.5 mg/kg twice a day (b.i.d.) based on the results of physical examination and laboratory testing on Day 14. Dogs in the control group received vehicle tablets. Doses were administered for approximately 28 days. All but one dogs received standard therapy for congestive heart failure : 125 (92%) dogs received furosemide (maximum 4 mg/kg/day) and 125 (92%) dogs received digoxin (maximum 10μg/kg/day) at the discretion of the investigator. Sixtyseven and 69 dogs were allocated to the control group and the enalapril group, respectively. Forty-four (66%) dogs in the control group completed the study when compared to 57 (83%) dogs in the enalapril group. The improvement from baseline to Day 28 was significantly greater for dogs in the enalapril group than for those in the control group for all scored parameters: activity, mobility, appetite, coughing, respiratory effort, pulmonary edema, and class of heart failure. Overall evaluation judged by the investigators were significantly better for the enalapril-treated dogs than for the control dogs on Days 7, 14 and 28. No differences were observed between the enalapril group and the control group for changes in all laboratory testing parameters (serum chemistry, electrolytes, etc.). No adverse reactions attributable to enalapril treatment were observed. The results of the study demonstrate that enalapril administered at 0.25 to 0.5 mg/kg s.i.d. with standard therapy of heart failure improves the clinical signs associated with heart failure. There were no enalapril-related adverse reactions.

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A 10-year-old female toy poodle dog was diagnosed as angiosarcoma of the right atrium. The ultrasonographic examination detected the tumor mass of 2 cm in the basal part of the right atrium, causing cardiac tamponade.
The autopsy revealed an angiosarcoma which may be resulted from repeated hemorrhage. There was no metastasis in other organs. Based on these findings, the lesion was diagnosed as the primary angiosarcoma.

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