_Definition._ A non-inflammatory enlargement of the thyroid gland,
independent of known microbes or parasitism.
_Causes._ Goitre is an endemic disorder in man and beast, though it may
occur sporadically during or after a _debilitating disease_, or in
animals that are overworked or out of condition. As occurring
endemically all accessory factors that undermine the general health must
be admitted as potent factors, though insufficient of themselves to
develop the malady in the absence of the specific cause. Thus in Europe
women suffer more than man, being more _confined indoors_ and being less
muscular and vigorous. In New York the new born offspring of ewes, kept
in close confinement during winter, may be all goitrous, while those of
flocks, having a free run through the whole season, escape. Gurlt has
seen the same in goats. Apart from debilitating diseases New York horses
and cattle develop the greater number of cases in winter, the period of
confinement and idleness. House dogs suffer more than hounds.
_Poor diet_ has a similar effect. In Europe where the disease is very
prevalent in the underfed peasant population, it is rare among the
highly fed domestic animals. Bouley says it is excessively rare in
animals even in the localities in which it prevails in man, and though
mentioned by Lydtin, Johné, Haubner and others it is not as a common
affection. In New York and Pennsylvania on the other hand it is rare in
the well-fed human population, and very common in horses, mules, cattle,
sheep, swine and dogs. I have known congenital goitre to prove fatal to
a new born dromedary in Central Park, New York. The long, severe winter,
close confinement, and impure air, doubtless as much as the spare diet
contribute to this prevalence among the animals in New York.
_Intestinal worms_ and other parasitisms must be accepted as secondary
factors, the development of goitre often going on simultaneously with
the increase of the parasites.
_Heredity_ is claimed as a cause by Möller and others, and doubtless a
weak constitution transmitted from parent to offspring, is more
susceptible. Apart from this the exposure of both to a common specific
cause is the main factor in its production.
_Locality._ This must be accorded a first position in the causation of
goitre, so far at least as it occurs endemically and enzootically. In
England it has prevailed, in man, on the limestone hills of Derbyshire,
and Gloucester (Cotswold); in Europe it is common in the Alps, Pyrenees,
Savoy, Styria, Silesia, in the Black Forest and in the Rhone valley; in
Asia it prevails in the Himalayas, the Altai Mountains, the hills of
China, and in the Punjaub; in South America it is seen in the valley of
the Oronoco; in North America in Saskatchewan, Ontario, Michigan, Ohio,
Pennsylvania, New York, Vermont, Virginia and Alabama. A large number of
these localities lie on magnesian limestone or are supplied with water
that has percolated through this, so that at one time the excess of
magnesia and the lack of iodine were held to be the main causative
factors. This contention cannot be sustained in all cases, so that the
disposition is, at present, to attribute the disease to some unknown
poison. This unknown poison may be present in districts apart from the
magnesian limestone, yet the disease is so frequently seen upon this
formation that its presence must always be looked upon with suspicion as
a probable bearer of the poison, and waters bearing its products are
unsuited to the victims of goitre.
_Pathological Anatomy._ Sometimes the swelling of the gland which
appears during catarrh or pharyngitis will subside on recovery. In other
cases it remains as a distinct hypertrophy. This is usually an increase
of the parenchyma and dilatation of its follicles with an albuminous
fluid (_hypertrophic goitre_). This may affect one lateral lobe or both.
In other cases the fibrous tissue mainly increases and the gland becomes
hard and resistant (_fibrous goitre_). In other cases the individual
follicles become distended, and may even break into each other forming a
large cavity or several with liquid contents (_cystic goitre_). In other
cases there is a great increase of the vascular network of the gland so
that blood alone is obtained on puncture (_varicose goitre_). Tumors of
all kinds may be found in the gland, thus encysted adenoma, sarcoma and
melanoma in horses, carcinoma in old dogs.
_Symptoms._ In _horses_ there may be swelling of one lateral lobe of the
gland or of both, reaching individually the size of a hen’s egg or the
fist, or larger. Cadeac cites cases that weighed 4 lbs. In _dogs_,
_cattle_, _sheep_ and especially in _swine_, the two lobes are much more
closely connected, and the disease affecting both, together with the
commissure, the whole may be resolved into one uniform swelling, much
larger than in the horse relatively to the size of the animal, often
covering the whole front of the neck, and extending into the chest.
Cadeac mentions cases in the dog in which the mass weighed 4 lbs.
The smaller swellings appear in the solipeds on the two sides of the
larynx, and in other animals more in front. They are mobile, but rise
somewhat with the larynx in swallowing, and are usually covered by
loose, movable skin. The consistency of the swelling varies; some are
soft, elastic or pitting on pressure, others fluctuate and still others
are firm and resistant. Old cases that have become calcified may even
feel bony. In dogs it will sometimes pulsate like an aneurism.
Functional secondary troubles are rare in solipeds. In the other animals
the goitre may compress the pharynx or gullet causing dysphagia, or the
larynx, trachea or recurrent nerves causing more or less wheezing or
dyspnœa. Asphyxia is not uncommon in new born sheep, and goats, and
Johné and the present writer have seen cases in dromedaries. The soft
embryonic tracheal rings had been so compressed from side to side that
respiration became impossible. Honert records a case of asphyxia in an
adult horse. Cases of _roaring_ in adult horses and mules and of
asphyxia in adult dogs are also on record. Warz records the obliteration
of the jugular in a dog, and Cadeac œdema of the lips and face.
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.