COLLECTIONS OF PUS IN THE GUTTURAL POUCHES.
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.