SPONTANEOUS CARDIOPULMONARY DISEASE IN 
NONHUMAN PRIMATES: POTENTIAL MODELS 
W. p. McNulty* 
Some spontaneous diseases of the heart and lungs of 
nonhuman primates offer promise for exploitation as 
models for human diseases for which etiology, patho- 
genesis, prevention, and treatment are poorly under- 
stood. Most of these are "subclinical." This may be due 
to both the young average age of animals in primate 
colonies and to difficulties with accurate clinical obser- 
vations. Generalized pulmonary arteriosclerosis and 
emphysema may accompany severe and prolonged in- 
festation with pulmonary mites. Clinical syndromes and 
at least suggestive postmortem findings indicate that 
both sudden, unexpected death in infancy and hyaline 
membrane disease may occur in monkeys. Pneumoconi- 
oses due to a variety of materials occur with regularity. 
No spontaneous autoimmune disease, comparable to 
asthma, Goodpasture's syndrome, or Hamman-Rich 
disease, has been recognized. Primary pulmonary neo- 
plasms have been very uncommon. Bacterial pneu- 
monias account for most clinical pulmonary disease in 
conditioned monkeys; the most common organisms are 
enteric bacteria. Viral pneumonias are common in the 
first weeks after arrival in this country. Neither acute 
rheumatic myocarditis nor chronic rheumatic valvular 
disease has been reported, and the carrier rate and 
susceptibility of nonhuman primates to beta-hemolytic 
streptococcus is unknown. Autoimmune alterations of 
cardiac valves, such as may be seen in systemic lupus 
and rheumatoid arthritis, have not been observed. The 
valves do change with age, though calcification and 
functional impairment have not been described. Chronic 
focal myocarditis of unknown etiology is commonly 
present in several species of monkeys, but is not known 
to be of clinical significance. Coronary atherosclerosis 
is unusual except in animals fed highly atherogenic 
diets, although aging macaques do show concentric 
cellular intimal thickening in coronary arteries. Spon- 
taneous cardiac anomalies occur but are rare. The 
major cardiopulmonary diseases of man become clini- 
cally significant late in life. Full use of nonhuman 
primates as models will require "geriatric colonies," i.e., 
maintenance of the animals for decades. 
INTRODUCTION** 
The use of nonhuman primates for medical 
research has disadvantages. They are expen- 
♦Oregon Regional Primate Research Center Beaverton, Oregon 
97005. 
'♦Publication No. 571 of the Oregon Regional Primate Research 
Center. This study was supported by NIH Grant No. RR 00163 to 
the Oregon Regional Primate Research Center. 
sive, to handle, and breed poorly, at least by 
comparison with established laboratory animals. 
But, as an item of faith, we who work with 
primates subscribe to the notion that in gen- 
eral the degree of similarity of disease in var- 
ious species should correlate with evolutionary 
relatedness. 
We seem to be on safe ground with respect to 
behavior and reproduction. The behavioral char- 
acteristics we share with monkeys and apes are 
obvious even at the zoo. Furthermore only mon- 
keys and apes share with us the monthly cyclic 
physiologic and endocrinologic phenomena of 
the menstrual period in the female and the sus- 
tained satyriasis in the male. 
In other anatomical and physiological sys- 
tems a close similarity, at least from the point 
of view of pathogenesis of disease, is not ob- 
vious. The diseases of most interest for investi- 
gative medicine are those we know the least 
about: etiology, pathogenesis and natural his- 
tory, and prevention, modification, and cure. 
Knowing little about these diseases, we cannot 
readily perform prospective investigations. We 
can, however, pay close attention to the spon- 
taneous ailments in monkeys, in the hope that 
we may see more or less similarity to human 
disease in clinical syndromes and pathologic 
changes. 
After nearly a decade of intensifying research 
with nonhuman primates, it is time to review 
the spontaneous diseases which have been found 
at autopsy. My remarks pertain only to the 
experience at the Oregon Regional Primate Re- 
search Center, and the interpretations are based 
solely on routine gross and light microscopic 
pathological examination. 
RESULTS AND DISCUSSION 
Approximately 4500 animals died since 1963 ; 
the majority of these were experimental sacri- 
829 
