What is it?
Urinary calculi is a common metabolic disease in male sheep and goats. The disease is caused when calculi (stones), usually comprised of phosphate salts, become lodged in the urinary tract and prevent urination. Phosphorus is usually recycled through saliva and excreted via faeces in ruminants. However high grain, low roughage diets decrease the formation of saliva which increases the amount of phosphorus excreted in the urine.
What causes it?

The primary cause of urinary calculi is feeding concentrate diets which contain significant amounts of phosphorus and magnesium or have an imbalance of calcium and phosphorus. Any feed which does not contain ammonium chloride which helps prevent rrinary calculi is not suitable to be fed to lambs.
Which animals are at risk?

Urinary calculi can affect intact male lambs and kids, however castrated lambs and wethers are most at risk. Lambs castrated within the first month are most vulnerable. Producers are therefore recommended to carefully consider whether it is necessary to castrate ram lambs. Intact males grow faster and produce leaner carcasses.
What are the symptoms?

The signs do vary, however they usually start with restlessness and anxiety. Affected animals may experience abdominal pain and urine dribbling which may be bloody. The lamb may have a humped up appearance and will isolate itself from others. If left untreated, affected animals will die when the bladder bursts and urine is passed into the blood stream.
How to treat it?

Treatment of urinary calculi depends upon the location of the obstruction and could just be a matter of snipping off the urethral process to allow the calculi (stones) to dislodge. Tranquilizers and antispasmodics may help to naturally dislodge some calculi. For valuable pets or livestock, surgical intervention may be necessary. It is much better to prevent urinary calculi rather than try to treat it.
How to prevent it?

As with many diseases, prevention is far better than cure, it can be prevented by feeding rations which contain a calcium to phosphorus ratio of at least 2:1. Neither magnesium nor phosphorus should be added to the concentrate diet. The use of ammonium chloride at a level of 0.5 percent of the total diet will help acidify the urine and prevent the formation of calculi. Roughage will also increase salivation and rumination which will increase the amount of phosphate excreted in the urine.