# Translational Echocardiography: The Dog as a Clinical Research Model of Cardiac Dysfunction
## 6 Dilated Cardiomyopathy (DCM), a Human and Canine Common Disease
### Echocardiographic Measurements on DCM
#### 6.1.4 Tissue Doppler and Speckle Tracking
In addition, these models face practical, technical, and scientific limitations inherent to the use of these species, for example: (a) The cardiovascular characteristics derived from their size, weight, and high metabolic rate make them very different from the human heart, especially in heart rate, oxygen consumption by the myocardium, contractility or isotropy, and response to drugs. (b) The difficult handling of these species makes them prone to stress during handling, with consequent cardiovascular physiological effects of elevated serum catecholamine levels. The tendency to develop arterial hypertension due to its management in the laboratory setting has made the murine model one of the most widely used models for the study of this condition, reaching the point of using hypertension induction methods that, in some cases, collide with important bioethical considerations regarding current scientific research. For example, arterial hypertension may be induced in rats that are semi-drowning in swimming pools which they cannot leave, meaning they must swim to survive, or hypertension may be induced by a combination of unilateral nephrectomy and a 10% sodium chloride solution orogastric tube [113]. (c) The need for aggressive manual or chemical containment employing sedation/anesthesia for clinical, electrocardiographic, and echocardiographic examination with the logical alterations of the cardiovascular variables to be evaluated, induced by the stress of handling or by the drugs used in the anesthetic plan. (d) The size of the murine models' hearts makes it difficult to obtain valid echocardiographic measurements, requiring special training for the staff, high-frequency ultrasound probes, and special adaptations of the software used for study interpretation. All of the above to make its implementation viable [114]. On the other hand, the dog, in its evolutionary process of more than 10,000 years accompanying the human being, has managed to adapt to its handling in such a way that, with minimum manual restraint (or sometimes without it), it tends to behave as an adequate clinical model, allowing painless procedures such as blood pressure measurement, electrocardiography, and echocardiography to be carried out without significant alterations, which will enable the evaluation of chronic diseases such as VMVD and CMD [111]. Furthermore, imaging acquisitions are ideal in cardiovascular disease animal models when performed with awake and cooperative animals, routinely performed in the dog during the follow-up of its cardiac pathology [5]. Echocardiography has become a systematic study in evaluating dogs' cardiovascular diseases because it is a minimally invasive procedure and is easily tolerated by dogs. Furthermore, the values obtained are reliable and repeatable since there is equipment adapted to the dogs' size and weight and computerized cardiology programs (software) adapted for the species, which correlate these values to the weight or body surface area of the patient, thus avoiding errors related to the variability of size, weight, and conformation of the thorax according to different breeds of dogs [101]. Currently, there are studies on dogs that show intervals or reference values, indexed to weight, breed, and even physical activity, for most of the normal echocardiographicparameters for measuring size, contractility, and ejection of the cardiac chambers, degree of deformation of the walls, and the morphometric comparison of the various structures that make up the heart [115]. Likewise, canine echocardiography in its different modes (B, M, color or spectral Doppler, Tissue) allows us to evaluate the thickness, motility, and degree of competence of the heart valves, as well as the direction and speed of transvalvular blood flow, and calculate pressure gradients, the stage stenosis of the valves, or post- stenotic dilatations, among other parameters, in a reliable and repeatable way.