Abstract: The assay was aimed to explore the effects of Ca²⁺ or K⁺ on dog cardiac function, and the role of Ca²⁺ and/or K⁺ on treating canine electrolyte disorders. 20 Chinese rural dogs at the age of 24 to 48 months were divided into two groups by age, gender and weight. Hyperkalemia (group Ⅰ) model was created by intravenous injection with 5% KCl at flow velocity of 1.5 mL/min, and then relieved the symptoms of hyperkalemia by intravenous injection with CaCl₂ at flow velocity of 1 mL/min; hypercalcemia (group Ⅱ) model was created by intravenous injection with 5% CaCl₂ at flow velocity of 1 mL/min, and then relieved the symptoms of hypercalcemia by intravenous injection with KCl at flow velocity of 1.5 mL/min.The blood was collected before and after the models built, and at the time of CaCl₂ (KCl) was injected to the models.The sera were separated and used to detect the concentrations of K⁺, Ca²⁺, Na⁺, Cl^-. Simultaneously, blood pressure, heart rates and electrocardiogram (ECG) were monitored at the same collecting points. The results showed that hyperkalemia model was established by intravenous injection with 5% KCl to the dog at flow velocity of 1.5 mL/min.At this time the serum concentration of K⁺ was significantly increased (P＜0.05),heart rate extremely significantly decreased (P＜0.01),SBP significantly decreased (P＜0.05). The ECG showed that the model dogs were arrhythmia, P wave became flat or even disappeared, T wave was tall as mantle.While CaCl₂ was injected to the hyperkalemia model by intravenous injection, the concentration of K⁺ was significantly decreased (P＜0.05),the heart rate significantly increased (P＜0.05), The ECG showed that P wave reappeared,mantle-like T wave disappeared.Hypercalcemia model was established by intravenous injection with 5% CaCl₂ to the dog at flow velocity of 1 mL/min.At this time the serum concentration of Ca²⁺ was extremely significantly increased (P＜0.01), the concentration of Na⁺ decreased (P＜0.05),the heart rate significantly increased （P＜0.05）,pulse pressure extremely significantly decreased（P＜0.01）. The ECG showed that T wave was widened,ST segment was shortened or even disappeared,QT interval was shortened,U wave was appeared.While KCl was injected to the model dogs by intravenous injection, the serum concentration of Ca²⁺ decreased (P＞0.05), the heart rate significantly decreased （P＜0.05） and returned to normal, but pulse pressure continued to decline.The ECG showed that T wave was apparently elevated.The time limit of ST segment increased.U wave was disappeared. The conclusions were that hyperkalemia (hypercalcemia) model could established after 5% KCl (5% CaCl₂) injected to the healthy dogs. The heart fuction recovered obviously when CaCl₂ was injected to the hyperkalemia dogs, therefore, CaCl₂ had a better therapeutic effect for hyperkalemia. However, it had no good therapeutic effect when KCl injected to the hypercalcemia dogs.

Key words: dog; hyperkalemia; hypercalcemia; electrocardiogram （ECG）; therapeutic mechanism