Since ultrasound imaging of the heart had become widely available, non-invasively evaluation of cardiac anatomy and function came to be the gold standard in diagnosing cardiac diseases. Nonetheless, the small size of cardiac structures in cats makes the echocardiogram a challenging procedure in this species, since a few millimeters can play a role in establishing an accurate diagnosis. Due to the lack of reference values for Doppler echocardiography in Brazilian Shorthair Cats (BSC), this study was conceived in order to study flow parameters across mitral, tricuspid, aortic, and pulmonic valves in such cats, aiming at facilitating a correct interpretation of echocardiograms.

For such, 32 healthy non-anesthetized cats (mean weight 4.33 kg) were divided into two groups: G1 had 16 female BSC, and G2 had 16 male BSC. Cats were first placed on right lateral recumbency and the exam was performed at the right parasternal location, where it was measured the peak velocity of the pulmonic flow (PVPul) using the short-axis view at the level of the aortic valve; the cat was immediately placed on left lateral recumbency, and measurements were done at the left apical parasternal view, where the following parameters were determined using the four or five-chamber views: peak velocity of the aortic flow (PVAo), peak flow velocity of the mitral E-wave (PVME), peak flow velocity of the mitral A-wave (PVMA), peak flow velocity of the tricuspid E-wave (PVTE), peak flow velocity of the tricuspid A-wave (PVTA). It was also calculated the relation between PVME and PVMA, as well as the relation between PVTE and PVTA. All parameters were measured using pulsed-wave Doppler. Groups were compared using Student's test at a significance level of 5%. To determine the 95% confidence interval (CI), it was used the average of both groups when statistical differences were not present.

Statistical analysis of data showed differences between G1 and G2 in none of the evaluated parameters. The following means and 95% CI were obtained (showed as mean±standard deviation; lower and upper 95% CI): PVPul (0.80±0.14; 0.75-0.85 m/s), PVAo (0.87±0.16; 0.81-0.93 m/s), PVME (0.72±0.17; 0.66-0.78 m/s), PVMA (0.57±0.12; 0.53-0.61 m/s), PVTE (0.65±0.14; 0.60-0.70 m/s), PVTA (0.48±0.12; 0.44-0.52 m/s), PVME/PVMA (1.25±0.30; 1.14-1.35), and PVTE/PVTA (1.34±0.27; 1.25-1.43).

Results contribute in standardization of Doppler echocardiography in BSC and will facilitate an adequate evaluation of cardiac flows in such animals.