THE USE OF LARGE ANIMALS IN EXPERIMENTAL 
CARDIOVASCULAR SURGERY 
J. N. Ross, Jr., J. M. Fuqua, Jr., B. S. Ruark, and J. H. Kennedy* 
Seven species are compared in terms of their use- 
fulness as experimental animals in a cardiovascular 
surgery program. The authors selected the calf since 
most of our work necessitated considerable handling of 
cardiovascular tissues, a tolerance to chronic transcu- 
taneous instrumentation, a tolerance to cardiopulmonary 
bypass and a tolerance to chronic mechanical circulatory 
support or replacement devices. The necessity for pre- 
operative conditioning is emphasized, as are the means 
of anesthetic and operative management. It was found 
that calves are relatively easy to manage postoper- 
atively; however, this does not mean that one can 
neglect them after intensive surgical procedures. The 
primary difficulties encountered when using this species 
in an experimental cardiovascular laboratory include 
their susceptability to upper respiratory infections, the 
fact that they are not mature animals, the fact that 
their thorax does not conform to that of man or sub- 
human primates, and the fact that electrical defibrilla- 
tion in larger animals is difficult with existing equip- 
ment. 
INTRODUCTION** 
Cardiovascular disease is the leading cause 
of death in the United States, and, in addition, 
15,000,000 Americans aged 18 to 79 have heart 
disease. 1 These facts have given rise to a vigor- 
ous research effort to develop techniques for 
prevention, recognition and treatment of cardio- 
vascular disease, as well as devices to assist or 
replace the failing circulation. To support this 
effort the larger laboratory mammals (i.e., sub- 
human primates, dogs, pigs, ponies, goats, 
sheep, and calves) have been used with increas- 
ing frequency primarily because of their size. 
Historically, several of these species have been 
intimately associated with the development of 
man and medicine, beginning with the domesti- 
cation of the pig and dog over 16,000 years ago. 
The early development of experimental medicine 
♦Baylor College of Medicine, Houston, Texas 
♦'Taub Laboratories for Mechanical Circulatory Support, Cora and 
Webb Madding Department of Surgery, Baylor College of Medicine, 
Houston, Texas 77025. Supported in part by HEW NIH grants 
HL-13330, HE-05435, and Special Fellowship ir03 GM 45166 (Ross). 
is generally associated with the Greeks. Galen 
used several species, especially the Barbary ape, 
relating structure to function within the mam- 
malian species, as he observed and dissected 
animals and cadavers from the arena, and he 
is credited with being the father of comparative 
anatomy and experimental medicine. ^ 
This paper summarizes our experience with 
380 calves in an experimental cardiovascular 
surgical laboratory and discusses the suitability 
of bovines relative to the other species listed 
above. 
EXPERIMENTAL OBSERVATIONS 
In the past five years over 380 calves have 
been used in our surgical laboratories for a 
variety of experiments including: the evalua- 
tion of prosthetic heart valves; the evaluation 
of the Baylor-Rice paracorporeal left ventric- 
ular bypass in normal animals and in animals 
with induced cardiac failure;^* the evaluation 
of other means of cardiac assistance such as 
intra-aortic balloon pumping and counterpulsa- 
tion ; for studies involving chronic implantation 
of instrumentation for hemodynamic measure- 
ments; and for evaluation of the Baylor-Rice 
total orthotopic cardiac prosthesis. 
Preoperative Care 
Problems were initially encountered in pro- 
curement. Calves purchased at a local sale barn 
proved to be completely unsatisfactory for ex- 
perimental surgery since 50% of these animals 
had upper and/or lower respiratory disease, 
parasitism or anemia. In addition, the animals 
were intractable. The seasonal unavailability of 
calves of the desired sex and weight range, 
particularly during the winter months was an- 
other deterrent to this form of purchase. Fe- 
male calves are preferred since catheterization 
417 
