The course of goitre is usually slow, extending over years, yet in young dogs it may make a very rapid progress. It will often stand still for a time, and later start a new growth under a fresh access of the cause. Spontaneous disappearance is rare.
Prevention. This is especially important in localities in which goitre is enzootic, and embraces careful attention to the general health, the avoidance of overwork, exhaustion, indoor life, lack of exercise, impure air, faulty feeding, starvation, and water from the goitrous soils. Rain water is preferable.
Treatment. First remove the various causes, and secure the best hygiene. If a change to a non-goitrous district can be had, avail of it.
Among medicinal agents iodine holds the foremost place. It may be given internally as potassium iodide, alone, or along with tincture of iodine, and applied locally as iodine ointment rubbed into the skin, or tincture of iodine painted on the surface.
Of surgical measures the simplest and best is the injection of iodine into the diseased thyroid. The nozzle of a hypodermic syringe is inserted into the gland, preferably into the largest cyst or follicular mass, and the liquid drawn off as fully as possible. It is then injected with the following mixture: compound solution of iodine one part, distilled water two parts. The amount may vary with the size of the goitre. In cases of moderate size ½ dr. to 1 dr. is suitable. There is usually some resulting inflammation, which may be met by a wet compress around the throat. A second and third injection may be made if necessary, when the effects of the preceding one have passed off. In simple forms it is very successful. For dogs Möller recommends from 5 to 15 drops of undiluted tincture of iodine at an injection. In other cases he used a watery solution of papain (1:10) to be left in for 48 hours. The thyroid was then soft and, on incision, discharged its digested parenchyma as a milky fluid, and favorable healing followed.
The removal of the diseased lobe has been successfully accomplished in horses, the reservation of the other lobe, or even of the connecting commissure, being sufficient to prevent the occurrence of tetany. From the extreme vascularity of the organ it is important to ligature the arteries before attempting the removal.
In the other domestic animals in which the commissure is practically obliterated and the two lobes confluent in goitre, the excision of the mass is liable to be followed by tetany, dropsy (myxoedema), stunted development, anæmia or marasmus. If a portion of the gland is left these results do not follow. Grafting of a portion of healthy gland may correct the tetany. The hypertrophy of the gland may sometimes be arrested by ligature of its nutrient arteries, and without the dangers above named. This may be combined with the internal and external use of iodine.
EXOPHTHALMIC GOITRE.
Definition. A complex disorder manifested by hypertrophy of the thyroid, excessive bulging of the eye balls out of the orbits, cardiac palpitations or tardy heart action and other nervous or trophic disorders.
Cadiot records a case in a horse, in low condition, with painful œdematous swelling of one fore foot, and swellings in other parts of the body, great enlargement of the left lobe of the thyroid, tumultuous heart action with beats 70 to 80 per minute, and strong visible pulsations in the superficial arteries. There was no leukæmia and no exophthalmia. The patient died on the third day.