This operation has been several times alluded to in connection with diseases of the urinary and generative systems. Its opportune performance may sometimes be the means of saving life, and of affording great relief in certain disorders, both in the male and female animal.

The male catheter (fig. 524) is an instrument some 4 feet in length, and composed of flexible material in order to accommodate itself to the curves over which it is required to pass on its way to the bladder.

It is hollow throughout its length, and commonly provided with a stilette of pliable material, such as whalebone. The end to be passed into the canal is provided with a nozzle of some harder substance, perforated in several places to admit the urine, and not therefore depending on a single orifice at the point, which may be blocked by mucus, blood, or other products of disease.

It may be passed when the animal is either standing or in a recumbent posture. If standing, the operator will adopt measures to secure his own safety, and take up a position on the horse's right side, where, with his left hand, he can seize the penis, and by exerting gentle but continuous traction overcome the resistance of the retractor muscles, and draw out the organ to its fullest extent. A little flour or meal upon the hand enables one the better to grasp and retain it, as the resistance is not inconsiderable, especially in stallions. The instrument, previously oiled, is then taken in the right hand and carefully introduced into the urethral canal. Provided no obstacle exists, such as a calculus from the bladder, it is advisable to push on with steady but continuous force until that viscus is reached. Should any opposition of the kind indicated be encountered, all effort to force the passage should cease, after a fair and reasonable attempt has been made to remove the obstruction. A careful operator will employ an assistant to watch the perineum and lightly press upon the part in order to direct the instrument over the curve of the pelvis, and give it a forward direction towards the bladder. It is important that the nozzle should reach as near as possible the. floor of the bladder, so that all the fluid may be drained oft"; care, however, must be exercised not to injure the organ by forcible contact.

Ecraseur.

Fig. 523. - Ecraseur.

Retention of Urine   Catheter inserted.

Fig. 524. - Retention of Urine - Catheter inserted.

A, Catheter, b. Bladder, c, Corpus spongiosum. D, Corpus cavernosum. E, Scrotum. F, Testicle. G, Ureter. H, Kidney. I, Aorta. J, Rectum. K, Anus. L, Prostate gland. M, Colon.

The stilette is next withdrawn, and a vessel held under the cup-shaped end of the instrument to receive the fluid. If no solid matters interrupt, the urine will flow as from a syphon in steady and continuous stream until but little is left behind; but it is generally considered advisable, where extreme distension has existed, to leave some portion of the fluid behind for a time, with the object of exciting contraction in the walls of the bladder and restoring its normal function.

The catheter is now withdrawn, and if any meal or other substance has been used on the hands, the penis should be cleansed, and some simple unguent applied within the sheath to facilitate the extrusion of the organ in the act of micturition.

Insertion of Female Catheter.

Fig. 525. - Insertion of Female Catheter.

A, Bladder. B, Catheter, c, Membranous fold overlapping the orifice of the bladder. D, Vagina.

E, Uterus. F, Rectum.

Among the chief disorders necessitating the employment of the catheter in the male animal may be mentioned retention of urine from stricture, enlargement of the prostate gland, the presence of calculi, injuries to the penis, morbid growths, inflammation of the bladder, and paralysis.

The female catheter (fig. 525) is a shorter instrument, and often composed of metal - a soft alloy, which will permit of slight bending. It is also made of caoutchouc, of cellulose, and other materials similar to those employed in the manufacture of male catheters. The orifice of the female bladder will be found on the floor of the vulva, about 4 to 6 inches from the labiae; an instrument, therefore, from 10 to 15 inches in length is found adequate for the purpose.

A fold of membrane slightly overlaps the opening, and when this is felt by the finger, the end of the catheter is directed to it and gently pressed forward and downward into the bladder.

Precautions for the safety of the operator are even more necessary in the case of mares than when attempting to withdraw urine from male horses (see Methods of Restraint).

The disorders calling for the use of the catheter in mares are, for the most part, the same as those for which it is employed in the male sex, but in addition there are troubles connected with the bringing forth of young which temporarily interfere with the passage of urine. Among these may be mentioned metritis, inflammation of the vagina after difficult and protracted labour, retention of the placental membranes, and maladies contracted in coitu.