Practice On The Dog

Categories: ACQUIRING SKILL
Sources: A Manual Of Peroral Endoscopy And Laryngeal Surgery

Having mastered the technic of introduction on

the cadaver and trained the eye and fingers by practice work on the

rubber tube, experience should be had in the living lower air and food

passages with their pulsatory, respiratory, bechic and deglutitory

movements, and ever-present secretions. It is not only inhuman but

impossible to obtain this experience on children. Fortunately the dog

offers a most ready subject and eed in no way be harmed nor pained by

this invaluable and life-saving practice. A small dog the size of a

terrier (say 6 to 10 pounds in weight) should be chosen and

anesthetized by the hypodermic injection of morphin sulphate in dosage

of approximately one-sixth of a grain per pound of body weight, given

about 45 minutes before the time of practice. Dogs stand large doses

of morphin without apparent ill effect, so that repeated injection may

be given in smaller dosage until the desired degree of relaxation

results. The first effect is vomiting which gives an empty stomach for

esophagoscopy and gastroscopy. Vomiting is soon followed by relaxation

and stupor. The dog is normal and hungry in a few hours. Dosage must

be governed in the clog as in the human being by the susceptibility to

the drug and by the temperament of the animal. Other forms of

anesthesia have been tried in my teaching, and none has proven so safe

and satisfactory. Phonation may be prevented during esophagoscopy by

preventing approximation of the cords, through inserting a silk-woven

cathether in the trachea. The larynx and trachea may be painted with

cocain solution if it is found necessary for bronchoscopy. A very

comfortable and safe mouth gag is shown in Fig. 73. Great gentleness

should be exercised, and no force should be used, for none is required

in endoscopic work; and the endoscopist will lose much of the value of

his dog practice if he fails to regard the dog as a child. He should

remember he is not learning how to do endoscopy on the dog; but

learning on the dog how safely to do bronchoscopy on a human being.

The degree of resistance during introduction can be gauged and the

color of the mucosa studied, while that interesting phenomenon, the

dilatation and lengthening of the bronchi during inspiration and their

contraction and shortening during expiration, is readily observed and

always forms subject for thought in its possible connection with

pathological conditions. Foreign body problems are now to be solved

under these living conditions, and it is my feeling that no one should

attempt the removal of a foreign body from the bronchus of a child

until he has removed at least 100 foreign bodies from the dog without

harming the animal. Dogs have the faculty of easily ridding their

air-passages of foreign objects, so that one need not be alarmed if a

foreign body is lost during practice removal. It is to be remembered

that dogs swallow very large objects with apparent ease. The dog's

esophagus is relatively much larger than that of human beings.

Therefore a small dog (of six to eight pounds' weight) must be used

for esophagoscopic practice, if practice is to be had with objects of

the size usually encountered in human beings. The bronchi of a dog of

this weight will be about the size of those of a child.



[FIG. 73.--Author's mouth gag for use on the dog. The thumb-nut serves

to prevent an uncomfortable degree of expansion of the gag. A bandage

may be wound around the dog's jaws to prevent undue spread of the

jaws.]