# Reference Intervals for Conventional Transthoracic Echocardiography and Two-Dimensional Speckle Tracking Echocardiography-Derived Strain Values in the Dutch Sheepdog (‘Schapendoes’)

## TL;DR

This study establishes breed-specific echocardiographic reference intervals for Dutch Sheepdogs and evaluates the impact of factors like body weight and heart rate on cardiac measurements.

## Contribution

The study provides novel breed-specific echocardiographic reference intervals and strain values for Dutch Sheepdogs using advanced imaging techniques.

## Key findings

- Body weight was the most significant independent variable for conventional echocardiographic measurements.
- Strain analysis was feasible, but heart rate notably affected radial and circumferential strain measurements.
- Anxious behavior in Dutch Sheepdogs, such as panting and tachycardia, affected image quality and analysis.

## Abstract

Echocardiography is the most commonly used diagnostic technique for cardiac examination when cardiac disease is suspected. Echocardiographic values in dogs can vary due to differences in body size, thoracic conformation, and activity levels. Therefore, breed-specific echocardiographic reference intervals are preferred. Two-dimensional speckle tracking echocardiography is an advanced imaging technique that allows for the measurement of deformation parameters, contributing to systolic function assessment for the entire ventricle (through global strain and strain rate) or its segments (through segmental strain and strain rate values). The aim of this study was to establish breed-specific reference intervals for conventional echocardiography for the Dutch Sheepdog and compare them with ranges commonly used in canine medicine. Furthermore, two-dimensional speckle tracking-derived strain and strain rate values were obtained. The influence of body weight, heart rate, age, and gender was assessed; inter- and intra-observer variability was determined. Reference intervals were generated from 60 dogs. Body weight was identified as the most significant independent variable for most conventional echocardiographic measurements of cardiac dimensions. Strain analysis was feasible, with the heart rate having notable effects on radial and circumferential strain analyses. Variability was acceptable for clinical use for nearly all conventional echocardiographic measurements, as well as for global strain. However, segmental strain analysis showed greater variability. Panting and tachycardia associated with anxious behavior commonly complicated echocardiographic assessments in Dutch Sheepdogs.

Echocardiographic values can vary between dog breeds, making breed-specific reference intervals (RIs) preferable. Two-dimensional speckle tracking echocardiography (2-D STE) is an advanced imaging technique that enables the measurement of myocardial deformation parameters, contributing to the assessment of systolic function. The objective was to determine breed-specific RIs for 2-D, M-mode, and Doppler-derived echocardiographic parameters for Dutch Sheepdogs, and to obtain 2-D STE-derived strain and strain rate values in this breed. Apparently healthy, purebred Dutch Sheepdogs (1–7 years) were recruited. Each dog underwent a physical examination and transthoracic echocardiography. Conventional 2-D, M-mode, and Doppler measurements were obtained; strain analysis was performed with 2-D STE software. RIs were established for conventional echocardiographic parameters; clinically relevant parameters were compared with commonly used RIs. The effects of gender, age, body weight (BW) and heart rate were tested. Sixty dogs were included. Panting and/or tachycardia were observed in 24 dogs, which affected the quality of the analysis to varying degrees (e.g., out-of-sector movement, lung artefacts). The selected parameters for left ventricular (LV) and atrial dimension showed good agreement with published RIs. BW was an independent variable influencing LV dimensions. This study provides RIs for conventional echocardiographic measurements and reports 2-D STE-derived strain and strain rate values obtained in Dutch Sheepdogs. The selected parameters of LV and left atrial dimension showed good agreement with commonly used RIs. Anxious behavior could represent a breed peculiarity to take into account when performing echocardiography, as it can affect image quality.