It is performed in the standing position, but is only possible when the animal is not too fat.
In other cases urethrotomy is performed opposite the point where the calculus is fixed, and aims at removing the obstruction. It can only be practised after casting the animal; but, in this case also, it is indispensable that the animal should not be excessively fat, as in such cases a secondary urinary abscess is almost certain to form.
Should the animal be so fat as to render treatment difficult, it is best to slaughter it at once.
URINARY CALCULI IN SHEEP.
Urinary calculi are commoner in sheep than in oxen, and seem to depend more on the breed and on conditions of feeding. They are almost exclusively confined to animals which are richly fed, to show animals, and to males. In exceptional cases they are seen, under ordinary conditions of feeding, in aged subjects.
Calculus formation can moreover be induced experimentally, and in a relatively short time, by giving certain rations—e.g., 7 lbs. per day of maize, lentils and beans for adults, and 3 lbs. for lambs. The other favouring circumstances, viz., hereditary gouty diathesis and infection, are less well established than they are in the case of the ox.
In sheep the symptoms are still less characteristic than in oxen, for which reason gravel in sheep merits special description.
It shows itself in the passage of turbid urine, forming a deposit at the extremity of the sheath, which becomes somewhat inflamed. The colic resulting from retention of urine is shown by depression, want of appetite, dysuria, and generalised convulsive shivering fits.
The patients lie down in the sterno-abdominal or sterno-lateral position. They constantly suffer from attacks of general violent shivering, and die after twelve, twenty-four, or forty-eight hours.
On post-mortem examination the bladder is found to be ruptured, or the urethra obstructed.