How does hypovolemia (i.e., dehydration) increase the circulating volume?
Hypovolemia causes an increase in renin secretion. The subsequent increase in angiotensin II causes an increase in blood pressure (as a result of arterial vasoconstriction), as well as renal sodium retention (this is both a direct effect and also the result of increased aldosterone secretion). With sodium retention, water is also retained. 7. How do you determine the degree of dehydration in an animal? Clinical assessment of dehydration is best accomplished by serial body weight monitoring. Experience has shown that the physical examination findings often underestimate the degree of dehydration. During the acute phase of volume depletion, these classical physical examination findings are all that are available. The chart below is offered as a general guideline and assumes more serious hypovolemia is present. TABLE 1. Estimating the percentage dehydration based upon physical examination findings.
