Morphometric measurements of the hearts in 48 racing pigeons (RP), a breed selected for long-distance flying, aged from 3 months to 10 years were compared with data from 65 feral pigeons (FP), the same breed as RP (Columva livia domestica), in order to clarify the quantitative morphologic features of athletic hearts of RP. Heart weight to body weight ratios were 15.3-16.8% higher in RP than in FP at a given age (P<0.01). Although there was no difference between RP and FP in cross-sectional area of the septal and left ventricular wall in a given transverse plane, myocyte cross-sectional area, and the capillary density calculated as number of capillaries per unit area of the myocardium, the dimensions of the left ventricular cavity and myocyte length were both significantly greater in RP (29.7% and 16.2-20.1%, respectively; P<0.001). From these findings, the greater myocyte length contributed to the higher heart weight to body weight ratio of RP and to the enlargement of the dimensions of the left ventricular cavity without a proportionate increase in the septal and left ventricular free wall area. In conclusion, the results of the present study suggest that athletic hearts observed in RP can be viewed as a form of the eccentric hypertrophy typical of volume-overloaded hearts that occurs with dynamic exercise training in long-distance runners, and that large hearts in RP has a genetic basis.

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We maintained thyroidectomized Wistar male rats for 70 weeks to evaluate the electrocardiographic effects of long-term hypothyroidism, which occurs in humans under treatment with amiodarone, a class III antiarrhythmic drug. We monitored the electrocardiographic changes in the hypothyroid rats up to 70 weeks after the thyroidectomy. Plasma levels of thyroid hormones significantly decreased starting 1 week after the thyroidectomy and remained low until the end of the 70-week observation period. Prolongation of the QT interval and bradycardia were significant from 1 week. However, the QT prolongation rate at 1 and 70 weeks showed no difference, indicating that QT prolongation was not enhanced by the hypothyroid state over the long term. In addition, there were significant correlations between plasma thyroid hormone levels and QT intervals or heart rates of the thyroidectomized animals. This finding suggests that these electrocardiographic changes were caused by hypothyroidism. Changes in the QT interval of animals that subsequently died or were sacrificed and in that of surviving ones showed no difference, and there was no arrhythmia detected during any of the recordings. Therefore, it is conceivable that the cause of the critical state or death might not be connected with the QT prolongation-related abnormal electrocardiographic changes.

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Among 632 cattle with congenital cardiovascular anomalies, additional six cases of criss-cross heart were detected. All cases had situs solitus of the atria and concordant atrioventricular connections. Concordant ventriculoarterial connections were present in two cases and double outlet right ventricles in four. All of these hearts did not show the supero-inferior ventricles but were associated with various congenital heart diseases.

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The purpose of this study was establishment of conditions to measure blood pressure by a oscillometric method in dogs. For this study, 27 dogs and noninvasive blood pressure taking instrument for animal (BP100D) were used. This study got the following results. There were not significant differences between each blood pressure value measured in a foreleg, a hind leg and a tail. However, as for the time before measured value of blood pressure fell, and being stable, the measurement with a tail was shortest in about 5 minutes. The hair of measurement region did not influence a value of blood pressure. The value of blood pressure in the same animal was not influenced in circadian rhythm by heart rate and rhythm. As for the value of blood pressure in the same animal, it was not influenced by environment of the measurement. However, as for the time before measured value of blood pressure fell, the measurement in an accustomed kennel was shortest in about 5 minutes. These results suggest that the oscillometric method is suitable for measurement of blood pressure in dogs using a tail in the environment where dogs can be relaxed, and we can use values of blood pressure after five minutes from start of the measurement.

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A new automatic system of sphygmomanometer based on the oscillometric method has been developed for animals, and the usefulness of this instrument (BP100D, Fukuda M.E. Kogyo Co., Ltd.) was evaluated in this study. Four beagles (average age 5.8 years old, average body weight 9.2 kg) were used for this experiment. The systolic, mean and diastolic blood pressures were measured by indirect method using this instrument and were compared to those measured by direct method (catheterized carotid artery) in unanesthetized dogs. A significantly high correlation (p<0.01) was obtained between the direct (actual) and indirect (oscillometric) blood pressure measurements. The systolic blood pressure showed the highest correlation coefficient (r=0.908), followed by those of the mean and diastolic blood pressures (0.853 and 0.800, respectively). Little variability was observed in repeated measurements of five times by four persons using this instrument. These results proved that this instrument was suitable for routine measurement of blood pressure in the unanesthetized dogs.

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Eleven non-pregnant cows, which were lactating, were used. The heart rates of the animals were measured at rest by electrocardiogram. The relationship between the heart rate and the milk yield of the day was studied, and a significant correlation was found between milk yield and heart rate.

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Three cases of congenital diaphragmatic hernia were detected in necropsied 9,267 cattle. Three cases of them showed the peritoneopericardial diaphragmatic hernia and the sternal part of their diaphragmatic muscular parts was absent. The herniated organs within the pericardial cavity were the rumen, jejunum, liver, and spleen in Case 1, the jejunum and liver in Case 2, and were not decided in Case 3. These three cases had the hypoplastic lungs and various intracardiac defects. The Case 3 showed the sternal cleft, gastroschisis and intracardiac defects.

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Percutaneous balloon dilation was performed on two canine cases of severe subaortic stenosis. As a result, Case 1 demonstrated the reduction of transaortic peak systolic pressure gradient from 128 mmHg to 75 mmHg. The dog has survived for 10 months after surgery in spite of one episode of syncope. Case 2 underwent cardiac arrest at the time of the balloon dilation, and was eventually euthanized owing to poor prognosis. This surgical procedure resulted in no satisfactory improvement. Terefore, indication of balloon dilation for canine subaortic stenosis should be carefully assessed and its efficacy for severe subaortic stenosis remains controversial.

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