PHYSICAL DIAGNOSIS OF THE LUNGS 119 



Physical Diagnosis of the Lungs. 



The lungs of the dog consist of a number of layer-like portions which 

 are united by the bronchi and connective tissue; the anatomical posi- 

 tions of the lungs are shown in Figs, 55 and 50. The left lung is divided 

 into two portions or lobes, an anterior and a posterior; the former is 

 again subdivided in two; this division is not very distinct in some eases. 

 The section that divides the large loljes begins opposite the fourth and 

 fifth vertebne and runs downward and backward as far as the sixth rib; 

 the anterior lobe extends as far as the first rib, and anteriorly and pos- 

 teriorly to the sixth rib; the large posterior lobe extends back as far as the 

 eleventh or twelfth vertebra, where it extends upward and lies between 

 the vertebra? and the diaphragm. The left lung has a small incision near 

 the heart, called the heart incision. The right lung is somewhat larger 

 than the left, and extends as far back as the twelfth or thirteenth verte- 

 bra; it is divided into four lobes, the posterior lobe being considerably 

 larger than the corresponding lobe of the left lung. The cardiac lobe lies 

 upon the heart, almost surrounding that organ; the other lobes hold the 

 same relation as they do in the left lung. The middle lobe of the lungs is 

 a club-shaped portion that lies in a special groove in the mediastinum, ex- 

 tending anteriorly as far as the heart and posteriorly to the diaphragm. 



In making an examination of the lungs we must take into considera- 

 tion the shape of the cavity of the chest, sensitiveness to pressure, the 

 number and character of the respiratory movements, the character of the 

 cough, and the information dcM'ived from auscultation and percussion. 



Shape of the Cavity of the Chest. — In healthy animals the two sides of 

 the chest should be symmetrical. A depression on one side means pain 

 in that portion of the chest, dry pleuritis, recent fractures of the ribs, one- 

 sided contraction of the lung after a rapid absorption of the exudate of 

 pleurisy. In a case where there is a fractured rib there may be a protru- 

 sion in one place, an inflammatory condition of the ribs, and tumors of the 

 wall of the chest; when the whole chest seems swollen, it indicates doul)le 

 pleuritis, with a great amount of exudate present; when only the posterior 

 half of the thorax seems distended and we find the abdomen enlarged, it 

 indicates ascites, tumors, or collections in the abdominal cavity. 



Sensitiveness to Pressure. — This is produced by a number of inflamma- 

 tory conditions of the skin and subcutis, the ribs, or the intercostal mus- 

 cles as in cases of muscular rheumatism, or in fracture of the ribs, and 

 quite frequently in pleuritis; in this case there is pain on pressure between 

 the intercostal spaces, and there may be great pain shown when there is 

 no exudate; this is a verv common symptom. For further information 

 see page 149. 



