By Richard Ehrhardt and Erin Recktenwald
What is urinary calculi?
Urinary calculi (or urolithiasis) is a condition where the urinary tract becomes blocked by calculi, or stones. These calculi are often phosphate salts, but they can be other substances such as silicates, calcium or oxalates. The blockage leaves the animal unable to void its urine either completely or partially, which leads to toxic waste products building up in the blood (uremia = build-up of and poisoning by urea) and eventually death occurs. Treatment is often not effective, making it a very serious condition, and the incidence rate can be high under certain conditions.
This condition is observed most often in young, castrated males. The reason for this is that males have a much longer and narrower urinary tract than females, and castrated males tend to have an even narrower tract due to lower testosterone levels during development. Blockages can occur anywhere along the tract but often are either at the small urethral process at the end or in the sigmoid flexure, an S-shaped curve between the bladder and penis. Calculi formation may occur with similar frequency in females, but they are rarely a problem due to the shorter and wider urinary tract. The good news is that this malady can be largely prevented with proper nutritional management; therefore, we classify this condition as a nutritional disorder.
Symptoms
An animal unable to void urine appears very uncomfortable. They will typically seem nervous or ill at ease, twitch their tail, vocalize and/or kick at their belly. They may arch their back and strain to urinate or may appear constipated. Their urine stream may be weak, intermittent or barely present. Blood and/or crystals are commonly present on the sheath. Either the bladder or the urethra may rupture within 1-2 days if left untreated, and the belly region will start to fill with urine; hence the common name of “water belly” for this nutritional disorder. Eventually, nitrogen-containing compounds and other metabolites will build up in the blood and cause uremia, quickly leading to death.
Treatment
As soon as a case of urinary calculi is noticed, Michigan State University Extension recommends examining feeding management. Adjusting the diet may be too late for the affected animal but may prevent the progression of this disorder in the rest of the feeding group. It is possible that acidifying the diet, as described later in this article, may have some therapeutic benefit if caught very early, but the success of this treatment is low. Treatment method and outcome depend on where the blockage occurs. If the calculi are at the urethral process (a thin structure extending from the penis), the process may be excised, which allows the calculi to exit. Be aware, however, that there may be more stones further up the tract than can pose more problems.
Source : msu.edu