Uroliathiasis in cattle and sheep: commonly known as kidney stones

These are a particular problems among steers and wethers, where the anatomical structure can predispose to obstructions in the urinary tracts.

Cause

This is primarily a nutritional disease among castrated male ruminants particularly among these males that have been castrated at an earlier age. High concentrate diets, with a low calcium to phosphorous ratio, or high in magnesium are a particular risk factor. The distal sigmoid flexture is the site most commonly associated with an obstructive uroliaths, because there is a natural constriction in the urethra, allowing the uroliaths to lodge there and cause a blockage to the flow of urine.

Symptoms

The presence of a uroliath lodged in the urethra is likely to be painful, with frequent attempts at urination, and the presence of blood tinged urine in partial occlusions. Where there is a complete obstruction, urine flow may stop completely, with additional signs of discomfort such as colic, tail swishing, straining. As cases advance, inappetance, bloat and depression can develop. As cases develop further, the bladder can rupture, which can lead to uraemia, this is likely to be fatal.

Treatment

Surgical removal of the uroliath is necessary if the urtethra is blocked. If affected animals become uremic (excess urea from the urine in the blood), rehydration and correction of the acid base balance is required. If the bladder is ruptured, this needs to be repaired, and dehydration must be corrected. The more advanced the case, the poorer the prognosis. In the early stages, conservative therapy using antispasmodics and tranquilisers can be used.

Prevention and control

Concentrate diets need to have a ratio of 2:1 of calcium to phosphorous to avoid the development of uroliaths. It is important to ensure wethers and steers on a finishing diet have access to water at all times. In addition, it is recommended that salt is added to the diet to increase water intakes.