Veterinary Clinical Medicine-I (General and Systemic)

PERCUSSION FIELD OF LUNGS

Lungs

• This is best carried out using a soft tipped acoustic hammer and a pleximeter. The lung area extends from its dorsal extremity at the 11^th intercostals space, across the middle of the 9^th rib to about two fingers breadth above the elbow joint when the foreleg is in a forward stance.
• On the right side, the posterior border of the lung field extends one (or) two fingers breadth further back (to about the 12^th rib) at its dorsal extremity compared with the left side, which is compressed slightly in the cranial direction (to about the 11^th rib) by the mass of the fore-stomachs.
• Acoustic percussion of the lung  is done in the first stage as horizontal percussion to establish the course of the caudal lung limits. This is best performed on the right side where the lung region is easier to differentiate from the adjacent areas of hepatic and omasal dullness than on the left side where the presence of rumen in the dorsal part of the field produces sonorous resonance which resembles that of lung apart from booming. Backward extension of thoracic field occurs in pulmonary emphysema and pneumothorax.
•  Restriction of the field from behind may be due to overloading of the fore-stomachs, enlarged liver, displacement of the abomasums to the right, severe dilation and displacement of the cecum, ascites, hydraminion and occasionally the uterus in advanced pregnancy.
• Next stage is the vertical percussion from above to below, commencing at the cranial edge of the thoracic lung field extending backwards at each intercostals space. Special attention should be paid to the air containing angle just behind the area of cardiac dullness, which becomes noticeably dull when the pericardium is enlarged by inflammation.