676 
PHYSIOLOGY 
procedures? I believe sometimes with muzzles 
like this the temperature may increase in ani- 
mals during this sort of procedure. Secondly, 
could compliance with age be a frequency de- 
pendent change, perhaps because of small air 
wave changes? Or, the other thing that I've 
heard about in beagles, is some sort of sponta- 
neous interstitial fibrosis with age. Is this a pos- 
sibility? Has this been looked at in any way as a 
cause of the change in compliance ? 
Dr. Mauderly: We measure body tempera- 
ture on each dog during the arterial bleeding 
procedure, not during the other procedures. We 
have measured the temperature in the series of 
dogs several months ago during the other proce- 
dures. We found that the mean body tempera- 
ture during our testing procedures is 102° F. 
Now, I'm not talking about the exercise proce- 
dures, but the other procedures. This doesn't 
represent a very large increase over what you'd 
expect for a normal body temperature. The dogs 
are very calm. The dogs that do show increases 
in temperature would be those which became 
excited, so forth, during the test, and these 
would be the dogs which would most likely have 
their tests repeated anyway, because of test val- 
ues received. So it hasn't been a problem for us. 
We make an effort to maintain the laboratory at 
a fairly even temperature, about 22° C, but we 
don't control it as closely as some people have. I 
don't really feel that body temperature is a very 
big factor. Now, where it affects the volume 
that we measure BTPS for our ventilation 
measurements, and where it affects the alveolar 
moisture or vapor pressure of water for our al- 
veolar arterial gradients, we do measure the 
temperature, because this is done during the ar- 
terial sampling procedures. So, these are cor- 
rected. 
Now in relation to the changes found in older 
dogs, I'm sure that from the few radiographs 
that we've seen the older dogs, that we do get 
some fibrotic changes in the lungs. We are just 
beginning. We've been involved in a very exten- 
sive program of placing young adult dogs on 
these toxicological studies and we're just now 
getting to the point where we're looking at 
large numbers of older dogs, and so I'd be much 
better prepared to answer your question in a 
few months. But we do see this reduction in 
compliance. I can't explain exactly why it oc- 
curs at this point, but it is a very consistent re- 
duction in compliance. The frequencies observed 
on the younger and older age groups were not 
significantly different. Now I haven't done ex- 
tensive studies of frequency and compliance in 
individual dogs, but we do measure this over a 
period of several breaths and I think the values 
we obtain are probably relatively accurate. 
K. Sagawa, Johns Hopkins, Baltimore, 
Maryland: Was the beagle particularly good 
from a behavioral viewpoint? Was that why 
you chose the beagle ? 
Dr. Mauderly: Well, this is the only dog 
we've worked with. We're working in a closed 
colony. We have about fifteen hundred beagles. 
We have our own breeding program located out 
of town. It's a closed colony so we haven't had 
an opportunity to work with other breeds or 
with mongrel dogs. We do find that beagles are 
very nice for these sorts of studies. I would ex- 
pect that we would have more problems if we 
were using pound dogs, or something like that. 
The beagle, as you all know, is a very even tem- 
pered animal. 
Dr. Sagawa: Was there any effect of re- 
peated tests on accumulated test results ? 
Dr. Mauderly: No, we have not found any 
as of yet. 
R. L. Hamlin, Ohio State University, 
Columbus: Have you tried to correlate any of 
the dynamic compliance measurements with 
static or quadristatic compliances in the same 
dogs, anesthetized, to see if the changes with 
age are not frequency dependent? 
Dr. Mauderly : Well I would have to say no 
and qualify it this way ; so far, as I said, we've 
been very busy with launching tremendous 
numbers of dogs on these studies and we've 
been somewhat restricted in the other projects 
we would like to work with. 
One thing we'd like to do, and intend to do, is 
to compare the effect of anesthesia with the ef- 
fect of different methods of measurement. Now 
I think those of you that are familiar with pul- 
monary function measurements are well aware 
of the fact that the results you obtain can be 
different, depending upon what technique you 
use. The same is true of the question of whether 
you're going to work with anesthetized or con- 
