Clinical Examination of Farm Animals - CYF MEDICAL DISTRIBUTION

Clinical Examination of the Respiratory System
Expiratory grunting
This is indicative of thoracic pain and may be heard
in cases of severe pneumonia and pleuritis. Inspiratory
and expiratory grunting may also occur in
severe cases of anterior abdominal pain, e.g. traumatic
reticulitis.
Physical examination
Physical examination of the thorax includes palpation,
auscultation and percussion.
Palpation
Chest palpation can be useful to identify thoracic
pain which may be caused by rib fractures and pleuritis.
Gentle pressure should be applied to the thorax
using the palm of the hand and the animal observed
for a pain response. The entire thorax should be explored
in a systematic manner to identify focal areas
of pain. In addition to pain, subcutaneous emphysema
may be detected as a spongy sensation which
may be accompanied by crackling noises. This clinical
sign is sometimes seen in outbreaks of respiratory
syncytial virus (RSV) and is caused by rupture of
emphysematous bullae in the lungs.
Auscultation
A good stethoscope with a phonendoscope diaphragm
is necessary to evaluate the breathing
sounds and detect abnormal sounds within the chest.
It is important to try to reduce or eliminate background
noises, such as tractor engines or milking machines,
which are common on most farms.
During auscultation the stethoscope should be
moved systematically to cover the whole of thoracic
lung fields with the aim of identifying any abnormal
sounds present, their location and their occurrence
in relation to the respiratory cycle. The location of
an abnormal sound is deduced from the position
of maximal intensity. Particular attention should be
given to the apical lobe if bacterial pneumonia is suspected,
or the diaphragmatic lobe if lungworm is
suspected.
Hyperventilation
This can be used to increase the loudness of normal
and abnormal sounds which may not be clearly
audible on auscultation if the animal is breathing
normally. Hyperventilation can be achieved by using
a rebreathing bag in small or docile animals. A
rebreathing bag can be constructed by securing a
long-arm plastic rectal glove over the mouth and
nostrils using a large elastic band. The glove is kept
in position for 30 to 60 seconds. This is shown in
Fig. 7.7.
Normal breathing sounds
These are produced by air movement through the
tracheobronchial tree, the intensity of the breath
sounds varying directly with airflow velocity. Air
movement in the terminal airways is inaudible. Normal
breathing sounds are loudest over the base of the
trachea and quietest over the diaphragmatic lobes
of the lung. The sounds are louder on inspiration,
which is an active process, than on expiration which
is passive. Thin animals have louder normal breathing
sounds on auscultation than fat animals. In
healthy cattle at rest the breathing sounds are quiet
and can only be heard by auscultation of the chest.
Extraneous sounds
These can be produced by regurgitation, eructation,
rumination, muscular tremors, teeth grinding,
movement of the animal causing hair rubbing, and
by normal and abnormal heart sounds.
Identification and interpretation of abnormal
breathing sounds
Referred sounds Care is required in the interpretation
of sounds heard upon auscultation. Sounds may
not relate directly to the area of the lung field under
the stethoscope but may be referred sounds. Sounds
emanating from the larynx can be heard over the
chest lung field, and tracheal auscultation must be
carried out to rule out referred sound from the upper
airway. The point of maximum intensity is greatest
over the source of the sound.
Increased loudness of the breathing sounds This
can occur in normal physiological states (e.g. exer-
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