Even when the urine appears to be aseptic, chronic exudative peritonitis is produced by the irritant action of the urine on the peritoneal endothelium. The exuded liquid mixes with the urine, and the animal soon shows marked ascites. Despite this condition, some animals have been known to survive as long as from three to six weeks without showing very marked disturbance.
Death is the inevitable sequel after a longer or shorter time. When large calculi have been arrested, or rather developed, in the bladder the same symptoms occur should the calculus be thrust towards the neck of the bladder so as completely to obliterate the passage. This, however, is a very rare accident. As a rule the obstruction is merely temporary, and the resulting vesical colic and retention last but a short time. The displaced calculus falls back again into the lower part of the bladder, where it is retained, and the urinary passages again become free.
Diagnosis. The diagnosis is sometimes extremely easy, but it may present serious difficulty.
When the urethra is obstructed, the symptoms are so striking that there can scarcely be any doubt; but the diagnosis of renal calculus, nephritic colic, calculus in the bladder, and rupture of the bladder demands more attention. Examination of the urinary organs through the rectum then proves of great service.
Prognosis. The prognosis is grave in all cases, because of the possibility of the urinary passages being obstructed, so that surgical interference is necessary.
Lesions. The lesions caused by urinary calculi may vary greatly. Though insignificant and scarcely apparent in certain cases, they are often very marked, and comprise simple or suppurative pyelitis, inflammation of the ureters, hydro-nephrosis, cystitis of varying intensity, urethritis, and inflammation of the sheath.
Treatment. All farmers who fatten their animals know that the use of alkaline drugs, such as bicarbonate of soda, together with diuretics, linseed, barley and pellitory diminish the danger of urinary calculus formation. Bicarbonate of soda is often given with this object, and is excellent in cases where lithiasis does not extend beyond the production of sandy or muddy deposits. By rendering the urine more alkaline it prevents the growth of sabulous deposits, and may even cause slow but progressive solution of concretions already formed. When, on the other hand, the urethra is obstructed, and urine is retained, early surgical treatment (urethrotomy) alone offers any chance of preventing rupture of the bladder.
Certainly it is possible, as recommended by the older practitioners, to try massage of the glans penis and urethra opposite the obstruction, and, after withdrawing the penis, to attempt to loosen and eject the obstructing matter. But such attempts very frequently fail, because the material is too firmly fixed, and no time must be lost.
Urethrotomy is usually practised at one of two points, according to circumstances—firstly, opposite the ischial arch; and, secondly, opposite the S-shaped curve.
Ischial urethrotomy is the promptest method of affording relief, and should always be preferred whenever there is danger of rupture of the bladder.