Hypertension is a major risk factor for death worldwide. Long-term hypertension causes changes in both diastolic and systolic left ventricular (LV) function, which ultimately lead to heart failure. In this study, image-based strain analysis was used to evaluate the progressive changes LV function (strain) over the lifespan of a commonly used animal model of hypertension. The novelty of the study was that each image dataset was analyzed over the cardiac cycle relative to an in-vivo reference configuration, thereby obtaining separate measures of diastolic and systolic strain, and enabling the assessment of the separate time courses of changes in diastolic and systolic function. The results indicated that decreases in diastolic function may have preceded decreases systolic function.