Cardiorespiratory Dynamics in the Ox and Giraffe, With Comparative Observations on Man and Other Mammals*

Abstract

Comparative mammalian physiology not only is important as an intellectual discipline in its own right, but it also provides a perspective which can contribute to the understanding of physiological processes in a given species.As an example, those functions of the organism which appear related to body weight or to body surface area can be studied over a wide range of animal size, providing more extensive data for the precise analysis of relationships than could be obtained from investigations confined to members of a single species. In recent years a strong increase in interest in physiological studies on large mammals has been evident.'-6 The discussion which follows is based on circulatory and respiratory observations obtained on four giraffe in South Africa a t an elevation of 2375 feet and on 26 domestic cows studied a t three centers in the United States a t 400 feet or less above sea level, as well as on data reported from other investigative groups. I n certain areas comparison of the findings in giraffe and cattle is made with those in man, dog, and other mammals. In the choice of material considerable selection has been exercised and preference given to findings providing new viewpoints for discussion or permitting direct comparison between species.The species of primary interest in this presentation-domestic cattle (cows) and giraffe-are large ruminants of approximately comparable body weight, namely, 650 to 1,450 pounds (295 to 659 kg.). Both of these animal groups belong to the same suborder (Pecora) but to different families, the Bovidae and Giraffidae, respectively. Although giraffe sometimes attain a height of 16 feet and are said to reach 20 feet rarely, the tallest animal in the present group was approximately 12 feet in height. FIGURE 1 shows this animal and a domestic cow of comparable weight in proper scale relationship. I t can be seen that although there is a striking difference in height (11'7.5" versus 4'6") the position of the heart is roughly halfway between hoof and head in both animals.

The digestive morphophysiology of wild, free-living, giraffes

“…What can be measured is Resting Metabolic Rate (RMR; mlO 2 /kg. min -1 ) and it has been measured twice in giraffes (Patterson et al, 1965;Langman et al, 1982). Their results differ widely.…”

The origin of mean arterial and jugular venous blood pressures in giraffes

“…After making measurements of giraffe blood pressure Goetz and Keen concluded that the giraffe cranial circulation proceeded unassisted by siphons or peristalsis although it was 'doubtless aided by subatmospheric pressures at the brain level' . Goetz and colleagues Warren et al, 1957) later concluded, however, that there was no 'necessity for any important contribution to cerebral perfusion pressure from negative venous pressure at brain level' (Patterson et al, 1965). If a siphon does exist then the origin of arterial blood pressure suggested by Badeer (e.g.…”

Lung volumes in giraffes, Giraffa camelopardalis

“…(Patterson et al, 1957) and (Patterson et al, 1965) compared giraffe and cow respiratory characteristics and also found a large dead space volume in giraffes (2.6 mL/kg vs 1.0 mL/kg in cows), a lung mass of the expected 1% of body mass but a "surprisingly small lung volume", and a higher respiratory rate. Inspiration time was prolonged compared to cows (ca 2 to 3 s vs 0.9 s respectively), expiration time was similar (1.62 s vs 1.67 s) and the average ratio of inspiration time to expiration time was 1.2 in giraffes and 0.6 in cows (Patterson et al, 1965). Conversely, Hugh-Jones et al (1978) found that while giraffe dead space was ca 3 mL kg −1 , it was 3.6 in deer (Cervus elephas), 3.1 in Llama (Lama glama) and 1.8 in camels (Camelus dromedarius), and thus was not unusually large.…”

“…Robin et al (1960) concluded that to overcome the large dead space the lungs were disproportionately larger and respiratory rate lower (8-10 bpm) than expected for similar-sized animals. (Patterson et al, 1957) and (Patterson et al, 1965) compared giraffe and cow respiratory characteristics and also found a large dead space volume in giraffes (2.6 mL/kg vs 1.0 mL/kg in cows), a lung mass of the expected 1% of body mass but a "surprisingly small lung volume", and a higher respiratory rate. Inspiration time was prolonged compared to cows (ca 2 to 3 s vs 0.9 s respectively), expiration time was similar (1.62 s vs 1.67 s) and the average ratio of inspiration time to expiration time was 1.2 in giraffes and 0.6 in cows (Patterson et al, 1965).…”