Clinical Examination of Farm Animals - CYF MEDICAL DISTRIBUTION

Clinical Examination of the Respiratory System
Trachea
Purulent
material
Narrowing
of the
bronchi
Emphysematous
bullae
Figure 7.8 Example of lung pathology which may cause
abnormal lung sounds.
Consolidation
Pleural
adhesions
the sounds produced with a consequent reduction in
loudness.
Abnormal lower respiratory sounds These include
clicking, popping or bubbling sounds, crackling
sounds, wheezes, pleuritic friction rubs and extraneous
noises. Clicking, popping or bubbling sounds are associated
with the presence of exudate and secretions
causing pressure fluctuations as the airway becomes
blocked and unblocked. Crackling sounds are associated
with interstitial pulmonary emphysema (RSV,
fog fever, husk). Wheezes are continuous whistling
squeaking sounds due to narrowed airways. Pleuritic
friction rubs produce a high pitched squeak during
the respiratory cycle and indicate adhesions
or other pathological changes which increase the
friction between the the parietal and visceral pleurae.
These changes result in pain during respiratory
movements and may be accompanied by grunting.
Sometimes it is difficult to distinguish whether the
source of the abnormal rubbing sounds is pericardial
or pleural. The breathing sounds can be eliminated
by covering the nose for 15 seconds which will eliminate
the sound if it is pleural in origin but not if it is
pericardial. This is very easy to do in calves, but is
often impossible in adult cattle.
Some examples of lung pathology which may
cause abnormal lung sounds are shown in Fig. 7.8.
Percussion
In percussion the body surface is tapped. The
audible sounds produced vary with the density of the
tissue set in vibration. As with auscultation it is only
possible to percuss a portion of the lung region
because much of the anterior lung field is covered
by the forelimb.
There are four methods of percussion available.
(1) Tapping the thoracic wall with the fingers held
slightly flexed. This method is simple and easy
to perform and is illustrated in Fig. 7.9.
(2) Placing the fingers flat against the chest wall and
tapping the fingers with the fingers of the other hand
vigorously. This can be quite painful to the operator,
particularly on a cold winter morning.
(3) Placing a flat oblong piece of plastic such as a plastic
ruler (the plexor) flat against the body wall and hitting
it with small rubber hammer or spoon (the pleximeter).
This is a useful method, although it may
startle the animal at the beginning of the procedure;
it is illustrated in Fig. 7.9.
(4) Transthoracic percussion. One side of the chest, for
example the left side, is repeatedly percussed at
a single location over the left dorsal lung field
whilst the entire right lung field is systematically
auscultated. As the stethoscope is moved over
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