CPD ACCREDITED ARTICLE
Urinary incontinence in these cases is considered to be ‘ idiopathic ’, and is often complicated by sabulous cystitis 19 .
III . Causes of urinary incontinence
• Neurological disorders : o Primarily UMN lesions : cervical spinal cord trauma , cervical stenotic myelopathy , EHV-1 myeloencephalopathy 1 , 2 , equine degenerative myeloencephalopathy , equine protozoal myeloencephalitis ( EPM ), aberrant larval migrans . o Primarily LMN lesions : polyneuritis equi , sorghum toxicity 3 , iatrogenic 4 , sacral vertebral trauma , osteomyelitis 5 , 6 and neoplasia .
• Non-neurological ( myogenic ) disorders : cystitis 7 ; urolithiasis 8 , 9 ; trauma ( e . g . bladder trauma secondary to dystocia ); neoplasia 10 , 11 ; ectopic ureter 12 ; hypoestrogenism or urethral sphincter hypotonia 13 , 14 ; musculoskeletal disease resulting in lumbar , sacral or hindlimb pain 19 .
• Idiopathic detrusor dysfunction : no primary neurological disease identified to explain bladder dysfunction . Often
16 , 17 , 18 chronic and complicated by sabulous cystitis
Figure 2 : Urinary incontinence in a gelding characterized by constant urine dribbling and penile paralysis .
IV . Diagnostic approach to urinary incontinence The clinical manifestations of urinary incontinence in the horse depend on the underlying disease process , but by definition , all horses will have a loss of bladder control which manifests as constant or intermittent dribbling of urine from the vulva or penis ( Figure 2 ). This can either be at rest or during exercise , and any activity that causes a sudden increase in intra-abdominal pressure may exacerbate the signs ( e . g . coughing ). In geldings and stallions , urine may be seen dribbling from the prepuce without protrusion of the penis . Affected horses usually smell of urine and in chronic cases , urine staining and scalding of the perineum in mares ( Figure 3 ) and the hindlegs in gelding may be evident . In some cases the horse may be able to urinate voluntarily despite being incontinent , but the stream is usually weak ( Figure 4 ).
Figure 3 : Urine staining and scalding of the perineum . Urinary incontinence in this case was caused by post partum bladder trauma and resolved with treatment .
Figure 4 : Urinary incontinence in a filly . The filly was able to urinate voluntarily despite being incontinent , but the stream was weak .
Depending upon the cause , other clinical signs may also be apparent and in some cases can be used to guide the veterinarian towards a preliminary diagnosis ( e . g . fever followed by sudden onset ataxia and paresis in cases of EHV- 1 myeloencephalopathy ). The initial assessment should be aimed at obtaining a minimum database of information that can be used to help generate a list of differential diagnoses and an appropriate diagnostic plan . An attempt should be made to differentiate between neurological and non-neurological bladder dysfunction , however it can be argued that this distinction is of academic interest only , as the treatment principles for urinary incontinence are similar , irrespective of the underlying cause . More importantly , a definitive diagnosis will enable to veterinarian to provide an accurate prognosis for the client .
History
It is important to obtain a detailed history in cases of urinary incontinence , as the inciting cause may have occurred many months prior to presentation . If any aspect of the history points to a primary disease , then that particular aspect should be focused on during the physical examination .
There does not appear to be an association between breed and urinary incontinence , however the gender of the horse can be important . Idiopathic myogenic bladder dysfunction occurs mainly in geldings 20 and oestrogen-responsive urinary incontinence has been reported in mares 13 , 14 . Reproductive status may also be relevant . Breeding injuries and dystocia has been reported to cause urinary incontinence in mares and owners may confuse frequent urination during oestrus as urinary incontinence . Ectopic ureters appear to be more common in females , although this may simply reflect the fact incontinence associated with ureteral ectopia is easier to recognise in females 12 .
The age of the horse will help rule out certain causes of urinary incontinence . Ectopic ureters and other congenital anomalies will cause incontinence that is present from birth 12 . Remember that foals with a patent urachus will dribble urine from the umbilicus and this may be misinterpreted as incontinence in colts . Osteomyelitis of the lumbosacral vertebrae caused by Rhodococcus equi has been reported as a cause of neurological urinary incontinence in foals 5 .
The environment and diet may also provide clues to the cause of incontinence . Ingestion of Sorghum spp . has vet360
Issue 02 | APRIL 2017 | 16