A 5-month-old intact female Scottish Fold cat weighing 2.1 kg was presented at Nippon Veterinary and Life Science University for consultation of cardiac murmur. The cat had no history of clinical signs. Careful auscultation detected a slight systolic murmur (Levine I/VI). Electrocardiography, thoracic radiography and non-invasive blood pressure measurements (systolic blood pressure 112 mmHg) were normal. At the first visit (day 0), conventional 2D and Doppler examinations were performed using a Vivid 7 echocardiographic system (GE Healthcare). The cat was not sedated, but was manually restrained in the right and left lateral recumbent positions. LV wall thickness was measured by 2D methods. The end-diastolic interventricular septum thickness was 4.5 mm, end-diastolic LV free-wall thickness was 2.7 mm, end-diastolic LV internal dimension was 12.2 mm, end-systolic LV internal dimension was 4.9 mm and fractional shortening was 50.4% on a short-axis view. All wall thicknesses, including the subaortic interventricular septum wall thickness on a long-axis view of 4.9 mm, were <6 mm, indicating the absence of LV hypertrophy. The left atrial to aortic root ratio derived from the 2D short-axis view was 1.6. Transmitral E- and A-wave velocities were 0.68 and 0.61 m/s, respectively. The deceleration time for the E-wave was 101 ms. The peak velocity of the LV outflow tract at rest was 0.8 m/s. This value slightly increased on excitation (1.2 m/s), although it was not found to be turbulent by pulse-wave Doppler methods. Obvious systolic anterior motion of the mitral valve or mitral regurgitation was not detected. Conventional 2D and Doppler echocardiography did not reveal any sign of HCM (). High-quality images for 2D-STE analysis were carefully obtained by the same investigator. Images were analysed using an offline EchoPAC workstation (GE Healthcare), as described previously. We measured the peak global and segmental systolic (S) strain and strain rate and the peak early diastolic (E) and late diastolic (A) strain rate in the longitudinal, circumferential and radial directions. The mean values of measurements for three consecutive cardiac cycles obtained from high-quality images were used in all analyses. Observer variability of 2D-STE analysis in our laboratory was previously described. Healthy cat ranges were established from a population of 14 young healthy cats (median age 10.0 months, median body weight 3.5 kg) as in this report. These cats are part of our previously published controls. Diastolic 2D-STE deformations on day 0 were dramatically different from healthy cats data (). The early diastolic strain rate (peak E) in the radial and circumferential directions was decreased. The early-to-late diastolic strain rate ratio (E:A) in the longitudinal, radial and circumferential directions was decreased. Although the global peak systolic 2D-STE variables on day 0 were within the healthy cats ranges (), post-systolic shortening during the diastolic phase () and lower and non-synchronous segmental strains (basal septum) corresponding to the gradually hypertrophied segments on follow-up examinations (subaortic interventricular septum) were observed (). Conventional 2D and Doppler examinations, and 2D-STE analysis were performed on days 90 and 150 using the same echocardiographic system by the same investigator. The LV wall thickness of the cat had gradually increased () and the papillary muscles had subjectively hypertrophied. On day 150, the end-diastolic subaortic interventricular septum thickness was 7.2 mm. Obvious systolic anterior motion of the mitral valve with mitral regurgitation and LV outflow tract obstruction (peak velocity of LV outflow tract was 3.9 m/s, with a turbulent Doppler signal) were also observed. We identified LV hypertrophy and made a clinical diagnosis of HCM. However, fractional shortening assessed by 2D methods was 37.1%. The left atrial to aortic root ratio derived from the 2D short-axis view was 1.6. Transmitral E and A wave velocities were 0.92 and 0.67 m/s, respectively. The deceleration time of the E wave was 113 ms. On day 150, 2D-STE revealed a decrease in the systolic global strains in the longitudinal, radial and circumferential directions (). Diastolic deformations were also observed (). Furthermore, the basal septum, middle lateral and basal lateral segmental strains in the longitudinal direction exhibited a decrease ().