DISEASES OF THE RESPIRATORY SYSTEM. 89 



Occasionally it may be necessary to perforin tracheotomy. 

 A little tempting liquid food ought to be placed before the 

 animal and frequently changed, even although untouched. 

 In chronic cases tonics are beneficial, in fact the treat- 

 ment above suggested for cases of chronic cough must be 

 tried, together with the application of blisters or other 

 stimulants to the throat, or a seton may be inserted. 

 Mayhew warns us that " the jugular veins in this animal 

 are connected by several large branches, which run just 

 where the seton would be introduced. These could not 

 be pierced with impunity, nor ought the seton to be left 

 in so long as might induce sloughing, when the vessels 

 probably would be opened ; for, as the dog badly sustains 

 the loss of blood, the result would surely be fatal." He 

 also says, " I found great improvement result from wearing 

 a very wide bandage, which was kept wet and covered 

 with oil silk, round the neck." 



Op the Essential Organs oe Kespiration. — The chest of 

 the dog is capacious, and highly expansile. The diaphragm 

 has but a small central tendon. The anterior opening 

 into the chest is much smaller than in the horse (rela- 

 tively). The left lung well overlaps the heart by its 

 middle lobe, a fact to be remembered in auscultation. 

 The pulmonary tissue is delicate but firm, and the air 

 sacs are large in proportion. The posterior mediastinum 

 is so stout as to suffice to prevent mechanical passage of 

 serous accumulation in the chest from one pleural sac to 

 another. The total amount of bone entering into forma- 

 tion of the walls of the dog's chest is very small ; his ribs 

 are rounded and not numerous ; their cartilages of elon- 

 gation are well developed and rounded ; the bones of the 

 sternum are numerous, rounded, long, and narrow. The 

 muscles of respiration are all much more fleshy than those 

 of herbivora, and the fore limbs may be freely moved 

 backwards and forwards. The dog, too, is more freely 

 manipulable for auscultatory purposes than larger animals, 

 accordingly the conditions are very favorable to the adop- 

 tion of auscultation as a means of diagnosis of his diseases. 

 The lung-sounds can be freely heard in almost every part, 



