PHYSICAL DIAGNOSIS OF THE LUNGS. 107 



only when the respiration is obstructed that the assistance of che 

 muscles of respiratiou is required in expiration. The works oa 

 physiology give more minut-e details on this subject. The normal 

 respirations are from twelve to eighteen per minute, the size of the 

 animal making a slight difference, in the smaller dog of course being 

 more. Various conditions tend to alter the above number, such 

 as running, physical excitement, overloading of the stomach, and 

 advanced pregnancy. While the respirations in the dog are regu- 

 lar, yet they are disturbed more quickly by physical excitement 

 than in any other animal. 



A pathological lessening of the number of the respirations may 

 be seen in all serious affections of the brain and its membranes; 

 in acute infectious diseases, such as septicaemia and distemper; and 

 in cases of contraction of the air-passages. 



A slight increase in the respirations may follow any increase of 

 temperature; they are also increased when any pain is present, in 

 circumscribed pleuritis, in the commencement of peritonitis, in 

 fractures of the ribs, and in rheumatism of the intercostals. Labor- 

 ious respiration (difficulty in breathing, dyspnoea) is seen where 

 there is any contraction of the pharynx, larynx, or windpipe ; for 

 instance, from the swelling and inflammation of the mucous mem- 

 brane in those organs, foreign bodies, tumors, etc. We see laborious 

 breathing, with great increase of the number of respirations, in any 

 irritation of the bronchial tubes where they become contracted or 

 filled with mucus, and in all diseases of the true lung-tissue ; in all 

 exudates into the pleuritic cavity, or in diseases of the abdomen 

 where there are collections of solids or fluids in the abdominal 

 cavity that press on the diaphragm ; in cramp, or spasm of the 

 muscles of respiration, as in strychnine-poisoning, tetanus, or 

 eclampsia in nursing bitches; in diseases of the heart where there 

 is stagnation of the thoracic circulation. In all cases of dyspnoea 

 in the dog the animal rarely lies down, but prefers to assume the 

 sitting position with the front legs spread wide apart. 



Cough. The nature and form of cough are very important 

 symptoms in all diseases of the respiratory organs. Cough is pro- 

 duced by reflex action from all parts of the mucous membranes of 

 the pharynx, windpipe, bronchia, and also by an inflamed pleura'. 

 The pulmonary tissue never produces cough by refl6x irritation. 

 The so-called "stomach cough" is only imaginary, no such 



