This study had the following aims: (i) to evaluate the circulatory galectin-3 levels in dogs with various diseases including cardiac diseases, (ii) to identify the difference between galectin-3 levels according to the type of heart disease or cardiac hypertrophy type, and (iii) to analyze the correlation between galectin-3 levels and conventional echocardiographic indices with NT-proBNP levels. The gene discussed is LGALS3; the disease is cardiac hypertrophy.