RESPIRATORY DISEASES OF 
DOGS, CALVES, AND SHEEP 
R. A. Griesemer* and R. L. Farrell' 
Naturally occurring diseases of the respiratory sys- 
tem are frequently encountered in experimental dogs, 
calves, and sheep. In a survey of 1,239 consecutively 
autopsied dogs, nearly all had anthracosis and the ma- 
jority of adults had pneumoconiosis. Up to 90% of 
dogs in the Ohio and Missouri river valleys have histo- 
plasmosis characterized by focal granulomatous pneu- 
monia and hilar granulomatous lymphadenitis. The ma- 
jority of dogs in the southern states have dirofilariasis 
that is not uncommonly associated with thromboembol- 
ism and arteritis of the pulmonary arteries. Young dogs 
that are immunosuppressed or severely stressed may de- 
velop lesions of infectious diseases during the experi- 
ment including the interstitial proliferative pneumonia 
of canine distemper, the focal fibrinonecrotic lesions of 
toxoplasmosis, and the tracheitis and bronchitis asso- 
ciated with herpesvirus, adenovirus, or parainfluenza 
virus. 
The most frequently encountered respiratory disease 
in calves is pneumonia. The primary etiologic agent is 
considered to be a virus. Since cattle have a deficiency 
of lung fibrinolysins compared with other species, fibri- 
nous pneumonias are not readily resolved and tend to 
persist with ultimate repair by fibrosis. It should be 
noted that in the calf and sheep, eructation provides an 
opportunity for inhalation of noxious gases from the 
rumen. 
Nearly every sheep is parasitized. The larvae of Oes- 
trus ovis cause chronic rhinitis and sinusitis and ac- 
j count for the exudate in the external nares of most 
sheep. Many sheep have pulmonary nematodiasis. Dic- 
tyocaulus filaria causes bronchiolitis and peripheral em- 
] physema while Mullerius capillaris lives in the alveoli 
and causes lobular pneumonia. An occasional adult 
sheep develops pulmonary adenomatosis or caseous 
lymphadenitis. 
1 
INTRODUCTION 
Naturally occurring diseases of the respira- 
tory system are encountered in all animal spe- 
cies. While the quarantine and conditioning 
process prevents severely diseased animals 
from being used in experiments, clinically inap- 
• National Center for Primate Biology, University of California 
Davis, California. 
Department of Veterinary Pathology, Ohio State University 
Columbus, Ohio. 
parent lesions may exist and interfere with the 
conduct of the experiment and with the inter- 
pretation of results. 
The purpose of this report is to describe some 
frequently occurring, spontaneous, subclinical 
diseases of the respiratory systems, of dogs, 
calves and sheep — animals commonly selected 
for respiratory experiments. It is hoped that 
the following descriptions of the lesions will aid 
in their recognition and emphasize the limita- 
tions of these species for research purposes. 
The major disease problems that can be recog- 
nized clinically by the laboratory animal veteri- 
narian are described in textbooks^'^ and will 
not be discussed here. 
RESPIRATORY DISEASES OF DOGS 
Anthracosis 
Since dogs live longer than most animal spe- 
cies employed in research and often share man's 
environment, it is not surprising that nearly 
every conventionally acquired dog has anthra- 
cosis. In a postmortem study of the lungs of 
1,239 dogs, we found a direct correlation be- 
tween the measured amount of pulmonary an- 
thracosis and the age of the animals. As might 
be expected, there was also a direct correlation 
between amount of anthracosis and smoke pol- 
lution in the environment in which the dog lived 
as measured by dirt fall collection. While car- 
bon pneumonoconiosis appears inocuous, its ef- 
fects on clearance of other substances is un-^ 
known at this time. We have observed increased 
localization of histoplasma organisms and dis- 
temper inclusion bodies in anthracotic nodules. 
Pulmonary Fibrosis 
Pulmonary fibrosis also becomes increasingly 
common with advancing age. Patchy areas of 
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