Structure, position and opening of pouches, inflamed by extension.
Symptoms, discharge intermittent with pendent head, swallowing,
pasturing, cough, roaring, dyspnœa, inhalation of food, parotid
swelling, glandular enlargement. Nature of contents. Treatment,
pasturage, blister, tonics, irrigation, puncture, injection.
Though this is commonly a result of severe sore throat or strangles, yet
as it causes a chronic discharge from the nose liable to be confounded
with those properly due to diseases of the nasal chamber, it is noticed
in this place.
The guttural pouches are two mucous sacs peculiar to solid footed
animals. They lie side by side above the throat, and in direct contact
with the lower surface of the superior bones of the head and the first
bone of the neck. They are properly speaking dilatations of the
Eustachian tubes which in all animals establish a communication between
the pharynx and the middle ear. The opening into the pharynx is at the
anterior extremity of the pouch and close to the posterior opening of
the nostril, hence the discharge takes place chiefly or exclusively when
the head is lowered, since gravitation then favors the escape of the
fluid.
Frequently implicated in severe sore-throat the walls of the guttural
pouches pour out pus as readily as other mucous membranes in a state of
inflammation. As the escape of this product is hindered alike by the
narrowness of the orifice and, in the elevated position of the head, by
gravitation, it frequently becomes imprisoned and inspissated and proves
a permanent source of irritation and discharge. In the early stages the
contents are glairy with whitish or yellowish clots; later they are
creamy, caseous or even cretaceous. The mucosa, at first red, congested
and tumefied, becomes in chronic cases, hard, thick, puckered and
adherent to adjacent structures. It sometimes ulcerates and the contents
escape in mass, through the pharynx and nose, or externally behind the
angle of the lower jaw. In the last case water swallowed may escape
through the opening. More commonly the pus remains pent up, and
thickens, and may dry and roll into round or oval pellets from the
movements of deglutition. The discharge may be arrested for weeks or
months when such masses block the outlet.
_Symptoms._ The nasal discharge is intermittent or irregular, being
often partially or wholly suppressed by keeping the head elevated, and
reappearing or becoming profuse when it is lowered. Feeding from the
ground, nibbling roots, or pasturing increases the discharge, as the
dependent position of the outlet, the jerking and shaking of the head
and the movements of deglutition all favor its exit. Swelling of the
parotidean region, a flatness instead of resonance on percussion, and
the flattening and discharge and sometimes gurgling by manipulation are
characteristic. There is cough, roaring during active exertion,
sometimes dyspnœa, and, in bad cases, food may be drawn into the
bronchia with serious and even fatal results. When the orifice is
blocked and the pouch filled with gas the elastic swelling and
resilience are characteristic, and pressure may flatten it with a
gurgling sound. These symptoms serve to differentiate it from
peripharyngeal abscess. The submaxillary lymphatic glands are usually
swollen but less than in glanders and not so hard.
_Treatment._ In mild and recent cases in which the contents of the pouch
have not yet become thick and dry, a cure may be effected; _in winter_
by feeding the animal from the ground and largely with roots; _and in
summer_, by turning out to grass. In either case the matter is allowed
to escape almost as soon as formed and the irritated membrane tends to
resume its healthy functions. This result will be favored by giving a
course of tonics as recommended in _simple ozœna_, and the application
of a mild blister to the throat.
Should this fail an operation must be resorted to. Günther, of Hanover,
uses an instrument in the form of a tube a yard long, half an inch in
diameter, slightly curved for two inches at one end which is blind, and
having an orifice on one side close to this extremity. This tube having
been introduced through the chamber of the nose on the affected side and
its curved end having been carried into the narrow opening of the
Eustachian pouch, tepid water is pumped in and the pouch thoroughly
cleaned out. Astringent solutions are then employed. The introduction of
the tube is, however, a very difficult operation and one quite
impossible to any one who has not the most accurate knowledge of the
parts in question.
A second mode of operating is by external incision. For this purpose are
wanted scissors, knife, artery forceps, iron probe bent in the form of
the letter S, and a tape. The horse having been thrown and fastened and
the head extended, the hair is removed from a surface in front of the
prominent border of the first bone of the neck, and an incision made
between this border and the parotid gland. The incision is made
immediately beneath a tendon which may be felt as a flattened cord
crossing the border of the bone in its upper third, and it should be
carried downward one and a half inches parallel to the margin of the
bone. In this preliminary stage the operator has to carefully avoid
injury to the parotid gland and the posterior auricular artery and vein.
The skin and fascia having been divided the index finger of the left
hand is pushed inward and forward until the prominent angle of the large
cornu of the hyoid bone is felt, together with the muscle (stylo-hyoid)
inserted into this bone above the angle referred to. The next step is
important since crossing on the inner side of this muscle and bone at
their point of union is the (internal carotid) artery which becomes
subsequently enveloped in a fold of the membranous wall of the guttural
pouch. The slightest variation in the position of the artery may here
prove fatal unless the greatest caution is used. With the knife guarded
by the index finger of the right hand the muscle is cut through from
behind forward and the pulsation of the artery felt for beneath.
Avoiding its position the knife, with its cutting edge turned forward
and its point directed toward the horse’s nose, is pushed through the
walls of the sac. The curved prob is now introduced and carried downward
until it is felt beneath the skin just behind the angle of the lower
jaw. This may be safely cut down upon with the knife as important parts
(vessels and nerves) have been turned aside by its pressure. A tape
attached to the prob is now drawn through the pouch and retained by a
knot on each end. Tepid water must be injected through the lower orifice
daily for three weeks, astringent antiseptic injections thrown in
occasionally and the horse fed from the ground. At the end of this
period the tape may be removed, and the wounds allowed to heal. During
the course of treatment it is always advisable to change the tape
several times by cutting the knot off one end of the old one, stitching
the new one to it and drawing it through.
_Puncture of the pouch at its lower part_ is a very simple operation
when the accumulation of pus is abundant and chronic. The distended
pouch gravitates downward largely separating the parotid from the deeper
vessels and nerves, and finally fluctuates toward the lower end of the
gland. In extreme cases it even opens and discharges. When fluctuation
can be felt the sac may be incised with a bistoury or abscess knife and
treated like a common sore. Opening with a pointed or olive-shaped
cautery has the advantage of checking hæmorrhage and securing more
perfect drainage. When there is no fluctuation the incision must be made
just beneath the lower border of the parotid, the parotidoauricularis
being first cut through, then the gland dissected from the deeper parts
when the distended sac can usually be felt and opened. If not felt at
once it can easily be reached by a careful dissection upward through the
loose subparotidean connective tissue, with the finger nail or handle of
the scalpel. A free opening may be made and the wound injected daily
with a weak antiseptic solution.