CHAPTER V.. Respiratory Apparatus.

RESPIRATORY APPARATUS.

TREPHINING THE FACIAL SINUSES.

This operation is necessary when pus, tumours, or parasites exist within the sinuses, and in some cases where tumours form within the nasal cavities, etc.

TREPHINING THE HORN CORE.

This cavity is opened in front, at the base of the horn, about ¾ of an inch above the keratogenous band.

FRONTAL SINUS.

The frontal sinus may be trephined at one of two points, that is, either towards its highest or lowest extremity.

In the former case the point selected is in the direction of the axis of the horn core, about ¾ of an inch nearer the middle line than the base of the horn itself.

The animal should be cast.

=First stage.= A =V=-shaped incision ¾ of an inch long on each side is made through the skin and subjacent tissues, exposing the bone.

=Second stage.= The skin and periosteum are dissected away and reflected upwards.

=Third stage.= Trepanation.

The lower portion of the cavity is trephined within the angle formed by a transverse line uniting the upper margin of the orbits and the inner margin of the super-orbital foramen.

The stages are precisely the same as those above described.

MAXILLARY SINUS.

In adult animals the maxillary sinus is opened immediately above the maxillary tuberosity. In the young the point selected is ¾ of an inch higher.

TRACHEOTOMY.

In bovine animals tracheotomy is only performed in urgent cases, in order to ward off asphyxia or to facilitate some other operation on the upper air passages. It is performed exactly as in the horse, the animal either standing or lying down. In the former case, the animal may be placed in the trevis, but two strong assistants holding the animal’s head and nose by means of “bulldogs” are often sufficient.

To prevent the animal from striking out with the front legs, a rope is passed above and around the knees in the form of the figure =8=; the animal is backed into a corner, and operation is then quite safe.

Large animals must be cast or placed in the trevis.

The seat of operation should be washed, shaved, and disinfected.

The operation may be divided into four stages.

=First stage.= Vertical median incision about 2 inches long through the skin at the height of the upper third of the trachea.

=Second stage.= Separation with a blunt director of the muscles covering the trachea. Incision through the pretracheal connective tissue.

=Third stage.= Circular or elliptical opening through the trachea of a size corresponding to that of the tracheotomy tube.

=Fourth stage.= Insertion of the tracheotomy tube.