Sabulous Cystitis in a horse!

The sample of urine in Figure 1 was collected from a gelding with the history of persistent urine dribbling or urinary incontinence.  The gelding was 20 years old and otherwise normal. A rectal exam revealed a large, distended urinary bladder that was so distended it hung over the brim of the pelvis!! The urine sample was milky and when allowed to settle there was a large concentration of sediment in the urine! These findings are consistent with sabulous cystitis in a horse!!

 

Figure 1

In Figure 2, the urinary bladder of the horse is labelled with the letter "B" and typically resides within the pelvis, immediately below the rectum. Emptying of the bladder or urination is a two-part process that involves relaxation of the bladder sphincter and simultaneous contraction of the bladder wall. This process is controlled by two distinct components of the nervous system which work together to empty the bladder and to keep urine in the bladder in between periods of voiding.

Figure 2

In the case of sabulous cystitis, the part muscle layer within the urinary bladder wall loses tone and does not contract properly during urination. As such, the bladder tends to remain full and will eventually over-distend. Fortunately for the horse, once the bladder over-distends, it begins to leak urine through the bladder sphincter and the horse dribbles urine on a regular basis. If the sphincter did NOT leak, the bladder would distend and ultimately rupture resulting in a medical/surgical emergency!! As a result of the over-filling, sediment tends to accumulate within the urinary bladder resulting in chronic irritation of the bladder lining and ultimately cystitis. The cause for the loss of bladder wall tone is unknown and there has been no proven treatment for this condition.These cases become management cases which includes regular "lavage" of the urinary bladder, systemic antibiotics for cystitis, and a reduction in any feed or supplements containing calcium.