Initially, the signalment, dietary and environmental history, onset of signs, duration, progression, and response to treatment should be established. Urethral calculi should be considered in castrated ruminants on high-grain diets. A history of one or more horses showing clinical signs of spinal cord disease, respiratory disease, stranguria, or urinary incontinence should immediately lead the practitioner to consider equine herpesvirus-1 myelitis in the differential. A history of dysuria or stranguria that develops after parturition usually indicates an injury to the lower urinary tract; such injuries can increase the female’s risk of subsequent urinary tract infection. For safety’s sake, the clinician should consider the potential for rabies as a primary cause before initiating the examination. A full physical examination should be performed because abnormal urination may be a sign of disease in other body systems, such as those characterized by diffuse muscular weakness. Common causes of dysuria, stranguria, and urinary incontinence are shown in Box 10-1.

The male’s preputial hairs and the female’s perineal region should be closely inspected for the presence of blood, exudate, or crystalline debris. Sedation and/or epidural anesthesia may be necessary to induce sufficient relaxation of the retractor penis muscles to enable examination of the penis. In prepubescent ruminants, the frenulum often prevents complete exteriorization of the penis for examination of the urethral orifice; general anesthesia may be necessary to induce sufficient relaxation. In bulls and steers, transrectal massage of the pelvic segment of the urethra may stimulate penile relaxation to enable penile visualization. The glans penis and urethral orifice should be carefully examined for masses such as papillomas, evidence of trauma, encircling hair rings, and embedded foreign bodies (e.g., grass awns). Penile examination is of particular importance in the dysuric or stranguric small ruminant because urinary calculi frequently become lodged in the urethral process (see Urolithiasis, Ruminants, Chapter 34).

An accumulation of smegma, composed of mucus and cellular debris, may cause preputial swelling and dysuria in adult male horses. Smegma can usually be found as a hard, waxy mass in the urethral diverticulum. Preputial swelling without overt urinary dysfunction may be seen in equine Cushing syndrome (see Equine Pituitary Pars Intermedia Dysfunction, Chapter 41).¹

In the male the penis and the urethra should be palpated percutaneously from the perineum distally to the sheath. Swelling, pain, abnormal urethral pulsations, and calculi lodged in the urethra may be detected. Urethral calculi are most commonly lodged just below the anus in male horses, and these can occasionally be palpated on the midline of the perineum. Marked swelling along the prepuce and ventral body wall in a bull or steer with active or recent dysuria/stranguria can indicate urethral rupture.

The vulva, caudal vagina, and urethral orifice should be visualized and palpated in females. Sacrocaudal epidural anesthesia may facilitate examination if painful lesions are present. In females of breeding age, the cervix should be visualized or palpated and the uterus evaluated by palpation or ultrasonography because the pollakiuria and apparent dysuria that may occur at the onset of parturition may be the primary complaint of a novice observer. Previous dystocia can result in sufficient soft tissue trauma, laceration, swelling, and pelvic neuropraxia to induce dysuria or stranguria. The ventrum of the tail, perineum, udder, and hindlimbs should be examined for adherent blood or exudate originating from the female’s reproductive or urinary tract.

In adult horses and cattle, rectal palpation should be performed when dysuria and stranguria are present. Before examination the clinician should take careful note of the tail and anal tone of the animal; reduction of either or both may indicate underlying neurologic or muscular disease. Introduction of the examiner’s hand and wrist into the rectum is usually sufficient for palpation of the pelvic segment of the urethra and bladder trigone. The caudal extent of the pelvic cavity should be carefully palpated for masses that might mechanically interfere with voiding. The bladder is typically located on the midline at the level of the pubic brim. Its presence in the caudal pelvic cavity, particularly in the standing animal, may suggest pelvic entrapment of the bladder.

Bladder distention is commonly found in persistently recumbent horses and cattle, and on rectal examination the bladder is often positioned farther caudally than in standing animals. In the horse, bladder distention may also be found with abdominal or thoracic pain. Apparently, the abdominal pressure necessary to empty the bladder incites sufficient pain of diseased structures to cause reluctance to void. Musculoskeletal and neurologic disease may also result in bladder distention. These other possibilities should be carefully investigated when bladder distention is detected, yet no primary disease is found in the urinary tract.

A careful rectal examination of the bladder and the proximal urethra of the horse might allow identification of urethral or cystic calculi. Most cystic calculi in the horse are singular and located in the trigone of the bladder and are palpable with the examiner’s arm inserted to the level of the wrist. If there is a large amount of urine in the bladder, the stone may not be palpable; in such cases, transrectal ultrasound examination may enable visualization of the stone. Sabulous calculi may be found in horses with stranguria or urinary incontinence, and on rectal examination the clinician may interpret the palpation findings as a bladder tumor or large stone.² Detection of calculi in the bladder or urethra should prompt the clinician to consider the possibility of concurrent nephrolithiasis.

If bladder dysfunction is not caused by structural abnormalities, trauma, or infectious disease, a thorough neurologic examination should be conducted. If neurologic dysfunction is suspected, an attempt should be made to determine whether the primary lesion is affecting the detrusor muscle or the urethral sphincter muscles of the bladder. This determination is often helpful in localizing the lesion and is important when selecting treatment.

When bladder paralysis is caused by upper motor neuron (UMN) dysfunction, signs of UMN dysfunction may be evident in the rear limbs. The animal frequently postures and strains to urinate but voids only a small amount of urine because the striated urethral muscles are disinhibited from higher centers and their resultant increased tone impedes urine outflow from the bladder. Frequent, small-volume urine egress from the distended bladder occurs when the animal responds to the urge to void or when the bladder undergoes reflex contraction.

With severe disease of the sacral spinal cord or sacral nerve plexus, lower motor neuron (LMN) input to the detrusor muscle is impaired or absent. Urinary incontinence is often the predominant clinical sign (e.g., cauda equina neuritis in horses or lymphoma in cattle). The bladder is usually moderately to severely distended, and urine can be expressed easily if pressure is applied to the bladder during rectal examination. With LMN dysfunction urine may also be voided as the animal walks. Voluntary or involuntary voiding is often incomplete, leading to retention of urine in the bladder. This, in turn, increases the patient’s risk of urinary tract infection and, in horses, sabulous calculi accumulation in the bladder. Other neurologic signs involving the sacral and coccygeal nerves may be apparent, such as decreased tail and anal tone and atrophy of the gluteal or tailhead musculature. Ataxia or weakness of the rear limbs may or may not be present with an LMN bladder. Urethral and bladder pressure profiles can be determined to better assess the location of the lesion.^3–5

In small ruminants and neonates, transabdominal palpation is useful for evaluation of the urinary tract. In these animals a distended bladder can usually be palpated by simultaneously placing one hand on each side of the caudal ventral abdomen at the level of the pelvic brim and pressing the fingers of each hand toward the abdominal midline. If the bladder has been ruptured, it will be difficult to identify by palpation but ascites due to uroperitoneum can be detected. Digital rectal examination of the pelvic segment of the urethra can be performed in neonatal cattle and horses and in small ruminants. The umbilicus should be carefully palpated in neonates with dysuria or stranguria because urachal abscesses and adhesions to the bladder may impair voiding. An infected urachus will occasionally communicate with the bladder lumen, creating concurrent septic cystitis.

Ectopic ureter(s) should be considered in young animals with persistent urinary incontinence; stranguria and dysuria are less common primary complaints. In affected females, vaginal urine pooling is often present. Vaginoscopic or cystoscopic examination can be performed, but the opening of the ectopic ureter can be difficult to locate during routine examination. Intravenous urography is typically required to locate the ectopic structure(s). As for all congenital defects, a careful assessment for defects in other organs should be performed in confirmed cases.

If physical examination and urinalysis do not reveal the source of dysuria, stranguria, or incontinence, ultrasonographic evaluation of the urogenital tract should be performed. An endoscope can be used for visualization of the vaginal vault and preputial cavity and penis; air insufflation can be used to expand the walls and achieve a clear view of these structures. When advanced retrograde into the urethra, the urethral wall, bladder, and ureteral openings can be visualized. In neonates and small ruminants, plain abdominal radiographs, positive contrast urethrocystography, and intravenous urography are additional options.