J. L. MAUDERLY AND J. A. PICKRELL 
669 
Figure 3. — Collection of femoral arterial sample. 
ing- into the muzzle area of the mask is con- 
nected to the inlet catheter of the mass spec- 
trometer, allowing respiratory frequency to be 
measured from recorded COo traces. The dogs 
are placed on the treadmill (18-49-D, Quinton 
Instruments, Seattle, Wash.), fitted with the 
mask, and allowed to rest quietly for 3 minutes 
to stabilize the breathing pattern. A timed 
collection of expired gas is then made, during 
which the breath-by-breath CO2 is recorded. 
Following the collection, the treadmill is started 
and the dog runs at 3.0 mph for 3 minutes, after 
which another timed collection is made. The 
treadmill speed is then adjusted to 4.5 mph, the 
dog is allowed to run at that speed for 3 min- 
utes, and the expirate is collected a third time. 
The breathing traces and collected gas tensions 
and volumes allow calculation of respiratory 
frequency, tidal volume, minute volume, O2 con- 
sumption, COo elimination, respiratory ex- 
change ratio, and specific ventilation at each 
speed. The treadmill is kept level throughout 
the procedure. Speeds higher than 4.5 mph were 
found to produce a panting breathing pattern, 
and 3.0 mph was selected as an intermediate 
speed. The exercise level, while considered only 
moderate, was found to be one that could be 
achieved by dogs with significant pulmonary 
abnormalities. 
Measured data for the calculation of most pa- 
rameters are entered on standardized forms for 
ease of key punching for computer input and 
processing. Both the input data and calculated 
results are placed in a temporary disc file and a 
printout is returned to the laboratory for vali- 
dation. After validation, the information is en- 
