Partial or complete inability to expel urine from the bladder by the usual natural method.
It is frequently due to spasmodic constriction of the neck of the bladder, and may also be the result of mechanical obstruction in the urethral canal. It sometimes occurs as a result of paralysis following on abnormal conditions of the brain and spinal cord. Among the mechanical obstructions may be mentioned enlargement of the prostate gland, the descent of calculi from the bladder into the urethral canal, stricture, morbid growths, swelling of the sheath, etc. Want of opportunity to stale is another frequent cause, as when thoughtless persons drive long distances and neglect to take the animal out of harness. It may be mentioned, inter alia, that while some horses will almost insist upon pulling up for the purpose of passing urine, others require perfect quietude, and can only be induced to stale by taking them on to a straw bed. It is occasionally found that a horse will not relieve himself while on a journey, although taken out of a carriage, unless the bridle is removed or the breeching. The inability to pass water after compulsory retention arises out of a temporary paralysis of the muscular coat of the bladder, the result of undue stretching.
Fig. 145. - Retention of Urine in the Mare - passing the Catheter A, Bladder, B, Catheter, c, Valve overlapping entrance to bladder. D, Vagina. E, Uterus. F, Rectum.
Repeated but unsuccessful attempts to urinate, standing with the front and hind legs far apart, straining, grunting or groaning, and possibly the passing of a few drops of urine, which seem rather to leak away than to be the result of effort. Rectal examination will confirm the diagnosis if any doubt or difficulty exists in determining between retention and non-secretion of urine. In the former condition the bladder can be distinctly felt to be distended with fluid, and in some cases the pressure of manipulation adds just sufficient force to expel a portion of it. In the latter the organ is more or less empty.
Fig. 146. - Retention of Urine - Catheter inserted.
If the urine has been long retained, and the bladder contains a large quantity, the catheter should be passed and the greater portion drawn off. Should there be indications of pain afterwards, warm fomentations to the loins, or a large poultice over that region, will have a soothing effect, and this may be increased by the admixture with it of extract of belladonna. The animal should be warmly clothed, and a dose of two or three drams of camphor dissolved in linseed-oil may be given, followed in two or three hours by one or two dram closes of extract of belladonna dissolved in linseed tea. Every inducement to urinate should be offered by placing the patient in a well - bedded loose-box undisturbed by other horses or their attendants. When retention of urine is connected with swelling of the sheath, the latter should undergo thorough cleansing with soap and water, and be afterwards lubricated with oil or vaseline. In extreme cases scarification with a small lancet may be called for.