104 DADD’S VETERINARY MEDICINE AND SURGERY 
to be about eight years of age, the tumors acquire such magni 
tude that they press on the vocal organs, so as to decrease the 
caliber of the larynx, and thus the animal becomes a “ roarer.~ 
Judging from what we know of the disease in the human supoject, 
the glands, while undergoing enlargement, do not occasion much 
pain. The danger arises from mechanical causes, and the death 
of the subject, if it occur, is due to asphyxia, or suffocation. 
Among horses there are very few fatal cases on record. The 
reverse is the case as regards sheep. When these glands are 
much enlarged, and the animal is near or past the adult age, it 
is very unsafe to attempt their removal by means of the knife; 
for at this stage they are highly vascular, and the arteries which 
ran into them are much enlarged. ‘The operation has been suc- 
eHOWIBG THE TCWOR OF BRONCHOOELE IN THE REGION OF THR THROAT, 
vewfally performed on lambs, but it must be done when they are 
quite young, and the artery must be secured before the gland is 
extirpated, or the animal will bleed to death in a few seconds. It 
is well known among the members of the profession that the dis- 
ease is incurable; and the same remarks apply to all hereditary 
diseases, yet the growth of the glands may be retarded by means 
of local and constitutional treatment. 
The thyroid glands are two ovoid bodies, varying in size from 
a filbert to an egg, located in the region of the thyroid cartilage 
(throat), one on each side of the trachea (windpipe). Their at- 
tachments are cellular. When cut into, they exhibit a porus tex- 
ture, highly vascular, well supplied with blood-vessels. Very 
little is known of their physiology. They are called vascular 
