Increases in circulating volumes and cardiac size with growth of White-tailed deer (Odocoileus virginianus).

Plasma and blood volumes determined by the T-1824 plasma-hematocrit method increase curvilinearly as captive female and male white-tailed deer (Odocoileus virginianus) grow in body mass from 6 to 61 kg (N = 40) and 9 to 93 kg (N = 34), respectively. Although comparable to other species of Cervidae, the weight-specific blood volume averages 33% larger than the interspecific mammalian value of 66 ml/kg body mass. The heart of white-tailed deer is also large, averaging 0.90% of the body mass (N = 53), about twice the ratio reported for domesticated ungulates. The cardiovascular demands attendant with a tenfold increase of body mass are apparently met by rapid increases in cardiac size (both mass and left intraventricular volume increasing curvilinearly with growth) and minute volume of the cardiac pump (cardiac rate and volume ejected per beat, inversely related to the other), which maintain fewer circulations of blood volume per minute with growth to heavier body size occurring from June to November.