This disease is usually seen in greatest severity in pups. It consists in an enlargement of the thyroid body, which increases so much as to destroy the life. In old dogs it is commonly stationary, or of a fixed size. Spaniels and terriers, are much exposed to it; and of the last-mentioned breed, probably bull-terriers are, of all animals, the most liable to be attacked.

In pups, the thyroid body greatly and quickly enlarges, so as to cut short the life by when the sixth week is attained. The disease of itself, in old dogs, is rather annoying than fatal; but the manner in which it destroys the animal when very young, is by impeding the circulation and respiration. The enlarged thyroid body presses upon the trachea and jugular veins. The blood which should return from the brain and head is thereby prevented descending, and hindered from reaching the heart in a full current. The vessels enlarge so as to become obvious to the most indifferent observer. The veins not only look swelled, but they feel turgid, and cannot be compressed; the little beast is dull; the breathing is very laborious; the animal sleeps much, and at last dies without a struggle, casting off life as it were but a troubled dream. It never has perfectly enjoyed existence, and its departure is not to be regretted.

With the older animals, so far as my experience at present teaches me, the thyroid body, when enlarged, has not suddenly increased; yet this fact by no means proves that the diseased part is always quiescent, and cannot increase in size. Because of this possibility, and the safety of the process, the disease should be eradicated. This is to be done by administering iodine by the mouth, and painting over the enlargement (having the hair first closely shaved off the part) with some of the tincture of the same drug, applied by means of a camel's hair brush. As iodine soon separates and is thrown down to the bottom, all the preparations of it should be used as freshly made as may be convenient. The mixture of which iodine is the active ingredient, and which is a week old, may be confidently said to have lost the major part of its virtue. Every three or four days this medicine should be concocted; for even when put into pills, iodine, being very volatile, will evaporate. The quantity to be given to the dog varies, from a quarter of a grain four times a day to the smallest pup, to two grains four times daily to the largest dog. The tincture used for painting the throat is made with spirits of wine, an ounce; iodide of potassium, a drachm.