In order to investigate the influences of acute hypercalcemia on the canine circulatory system, the changes in serum electrolyte concentration, electrocardiogram, blood prassure, body temperature and hematocrit values in anesthetized beagle dogs were observed for 24 hours from the onset of the intravenous infusion of calcium chloride solution (CaCl₂). Four male beagle dogs (age : 12-19 months, body weight : 9.1-12 3 kg) were anesthetized with pentobarbital sodium and received 0.9% sodium chloride (NaCl) and 60, 120 and 240 mg/kg of CaCl₂ successively at 2-week intervals. The solutions were given by an infusion pump for 2 hours at a rate of 0.7 ml/min. The results obtained were as follows:
1.The serum concentration of Ca increased in a time- and dose-dependent manner during the CaCl₂ administration, and the peak of Ca serum level was found at the end of infusion. In the dogs given 240 mg/kg of CaCl₂, the highest peak value in Ca serum level reached was 23.1mg/dl, which was 2. 3-fold pretest value (10.5mg/dl). The Ca concentrations in all dogs decreased promptly after the end of infusion and returned to the pretest level by 24 hours after the infusion. The serum concentration of Na was significantly decreased by CaCl₂ administration, but the concentrations of K and C1 were not affected.
2. QT interval corrected to heart rate of 100 bpm (QTc₁₀₀) was slightly shorter in CaCl₂ groups than in the NaCl group up to an hour the after the infusion. QRS complex duration and PR interval were inclined to be prolonged and ST segment to be elevated in the CaCl₂ groups, but the amplitudes of P, R, S and T waves were not affected by CaCl₂ administration.
3. Heart rate decreased toward the end of CaCl₂ infusion at a dose of 240mg/kg and lasted for an hour after the infusion. Rectal temperature and hematocrit value similarly decreased in both NaCl and CaCl₂ groups during the infusion. These parameters returned to the pretest level soon after the end of infusion in the NaCl group, while recovery in CaCl₂ groups was slower, corresponding to the recovery from anesthesia. There were no significant differences between the two groups in blood pressure changes.
4. Dogs in the NaCl group recovered normally from anesthesia, becoming conscious state 3 hours after the infusion. Recovery from anesthesia in the CaCl₂ groups was slower. Dogs given 60 and 120 mg/kg of CaCl₂ were not yet conscious 3 hours after the infusion, and those given 240 mg/kg of CaCl₂ were deeply anesthetized. All dogs recovered completely 6-8 hours after the infusion.

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Mitral regurgitation (MR) is a common cardiac disease in the dog. It is more frequently diagnosed in small dogs than large ones. We investigated the epidemiology of MR in Maltese dogs, which was one of the most popular breeds in Japan. The prevalence of MR was defined in 460 (male : 230, female : 230) cases of Maltese dogs. MR was diagnosed by radiography and/or2-D echocardiography. 23.5% of all cases were diagnosed on ausculation to have a systolic regurgitant cardiac murmur. MR was diagnosed in 97% of cases which had systolic regurgitant cardiac murmur. The remaining 3% of cases had other cardiac diseases causing systolic regurgitant murmur. The sex ratio of MR cases was male: female= 1.4 : 1.0. The earliest onset of systolic regurgitant murmur was 5 years old, and the most frequent age of onset was 9 years old. Of the dogs that died, 54% of male and 32% of female dogs died as a result of heart failure.

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A 6-month-old female Golden Retriever was presented to Azabu University Animal Hospital for evaluation of a congenital heart disease. Findings fo the right ventricle, which was divided into two chambers by abnormal muscle bands, were detected by two-dimensional and pulsed Doppler echocardiographic examinations. Furthermore, measurement of blood pressure by cardiac catheterization demonstrated a 5.5 mmHg pressure gradient between the two chambers in the right ventricle.
At three and six months after the initial examinations, this disease was re-evaluated. In pulsed Doppler echocardiography, blood velocity in the right ventricular outflow tract tended to increase, and progression of the obstruction in the right ventricle was suggested.
These findings suggested that the cardiac pathophysiology of this case was progressive cardiac disease.

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Double-outlet left ventricle (DOLV) was observed in three (0.9%) of 329 bovine hearts with congenital cardiac anomalies. All three cases presented visceroatrial situs solitus and atrioventricular concordance in the hearts, each of which had two well-devloped ventricles. In cases 1 and 2, subaortic ventricular septal defect (VSD) and pulmonary stenosis were evident. In case 3, doubly committed VSD and coarctation of the aorta were detected.

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Clinical examination of a two-month-old foal revealed evidence of progressive heart failure associated with atrioventricular valvular insufficiency and atrial fibrillation. Atrial fibrillation is rarely reported in foals. This report describes the clinical, electrocardiographic, echocardiographic, and necropsy findings in the case.

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