Micturition Disorders and Prostatic Disorders Study Notes

MICTURITION DISORDERS AND PROSTATIC DISORDERS

LECTURE LEARNING OBJECTIVES

  • Understand the components that are involved in normal micturition.

  • Be able to form a diagnostic plan for the incontinent patient.

  • Be able to form a diagnostic plan for a patient that cannot urinate.

  • Understand indications for treatments used to manage incontinence and urinary retention.

MICTURITION

  • Definition: Micturition is defined as the controlled voiding of urine.

    • Bladder stores urine for 99% of time.

    • Bladder voids urine for 1% of time.

  • Micturition Disorders Manifestation:

    • STORAGE DISORDER: Inability to control the voiding of urine leading to incontinence.

    • VOIDING DISORDER: Inability to initiate or complete urination leading to urinary retention.

NEUROANATOMY OF MICTURITION

  • **Brain Segmentation:

    • L1 – L4 (dog)

    • L2 – L5 (cat)

    • S1 – S3

  • Muscle Innervations:

    • ESM (External Striated Muscle) - Skeletal

    • Detrusor Muscle - Smooth

    • ISM (Internal Striated Muscle) - Smooth

  • Conscious awareness of urination requirement:

    • Controlled via sympathetic and parasympathetic input.

  • Micturition Control Mechanism:

    • Storage Phase: Detrusor is relaxed; sphincter muscles are contracted.

    • Voiding Phase: Detrusor contracts and sphincter muscles relax.

NEUROLOGICAL ASSESSMENT

  • Assess:

    • Anal tone & sensation.

    • Rectal exam.

    • Bulbocavernosus and Perineal Reflexes:

    • Pinch bulbus glandis (or vulval commissure).

    • Stimulate perineum to observe for anal sphincter contraction and tail clamp.

    • Urethral sphincter tone.

    • Caution advised during bladder compression due to the risk of bladder rupture.

RESIDUAL BLADDER VOLUME

  • Assessment can be performed by:

    • Allowing the patient to void urine.

    • Once finished, catheterize and drain the bladder to measure the volume recovered.

    • Noted that this process is generally easier for males than females.

LESION LOCALISATION

  • **Factors for Diagnosing Micturition Disorders:

    • Conscious voiding attempts.

    • Bladder expression.

    • Bladder size.

    • Residual urine volume.

    • Perineal reflex presence.

    • Type of micturition disorder**

NWomen and Men: Micturition Disorder Types

  • Cerebral Cortex to Brainstem:

    • CONSCIOUS VOIDING: Absent, attempted.

    • Bladder expression: Difficult.

    • Bladder size: Small.

    • Residual urine: Small.

    • Perineal reflex: Present.

    • Disorder: Inappropriate urination.

  • Cerebellum:

    • Voiding attempts: Normal or increased frequency.

  • Sacral Spinal Cord:

    • Bladder expression: Absent or may attempt without success.

    • Residual volume: Large.

    • Disorder: Urethral incompetence.

STORAGE DISORDERS

  • Incontinence Types:

  • Mechanical Causes:

    • Anatomical abnormality (congenital/acquired).

    • Examples: Ectopic ureter, genito-urinary dysplasia, perineal urethrostomy, urethral stent.

  • Functional Causes:

    • Urethral sphincter mechanism incompetence (USMI).

    • Detrusor hyperreflexia.

    • Lower motor neuron bladder.

URETHRAL SPHINCTER MECHANISM INCOMPETENCE (USMI)

  • Most common cause of incontinence, primarily seen in neutered female dogs.

  • Affects large breeds (>20kg), especially if neutered before the first season.

  • Predisposed Breeds: Doberman, Giant Schnauzer, Old English Sheepdog, Rottweiler, Boxer, Weimaraner.

  • Hormonal Influence: Estrogen increases α1 receptor expression causing contraction of ISM. Middle age onset, but younger ages can be affected.

Clinical Features of USMI

  • Incontinence usually occurs when the dog is asleep or lying down.

  • Physical examination sometimes reveals unremarkable findings, but symptoms may include:

    • Vaginits.

    • Urinalysis shows normal USG, but conditions causing polyuria may exacerbate incontinence.

    • Secondary infections due to an open urethra are possible.

    • Urethral pressure profiling is a gold standard for diagnosis, but rarely performed.

TREATMENT OPTIONS FOR USMI

  • Estrogen (Estriol): Increases responsiveness of α adrenergic receptors to noradrenaline; effective in 65% of cases.

    • Dosage: 0.5-2mg per dog every 24 hours (use lowest effective dose).

    • Side Effects: Vulvar swelling, attractiveness to male dogs, vulvar discharge, myelosuppression.

  • Phenylpropanolamine: Sympathomimetic acting on α adrenergic receptors; effective in 75-90% of cases but needs frequent dosing and monitoring for hypertension and side effects like restlessness.

Surgical Interventions for USMI

  • Options include:

    • Colposuspension.

    • Urethropexy.

    • Vas deferensopexy.

    • Artificial urethral sphincter.

    • Bulking agents (Botox, collagen, gelatin).

    • Require repeated applications every 6-10 months.

ECTOPIC URETERS

  • Definition: Congenital abnormality with ureteric openings positioned caudal to trigone; more often affects females.

  • Common Breeds Affected: Golden retrievers, Siberian huskies, Newfoundlands, poodles.

  • Clinical features include:

    • Incontinence from a young age.

    • Potential recurrent infections.

DIAGNOSTICS FOR ECTOPIC URETERS

  • Diagnostic imaging required to establish:

    • Whether the condition is unilateral or bilateral.

    • Whether ureters are intra-mural or extra-mural.

    • Intra-mural: Ureters open into the bladder wall and tunnel along the urethra.

    • Extra-mural: Ureters open directly into the urethra (more common in cats).

    • Hydronephrosis may develop due to recurrent infections.

DIAGNOSTIC IMAGING TECHNIQUES

  • Intravenous Urethrogram: Administer enema prior to the procedure for better visualization of ureters.

  • Ultrasound: Administration of furosemide can assist in visualizing ureteric jets.

  • Cystoscopy: Allows for diagnosis and potential simultaneous treatment.

ECTOPIC URETER TREATMENT OPTIONS

  • Surgical Techniques:

    • Laser ablation.

    • Neoureterotomy (intra-mural).

    • Ureteral reimplantation (extra-mural).

    • Ureteronephrectomy (may be necessary due to concurrent hydronephrosis or pyelonephritis).

Detrusor Hyperreflexia

  • Condition: Urge incontinence due to involuntary loss of control triggered by sudden urge to urinate.

  • Diagnosis requires cystometrogram, though rarely performed.

  • Treatment may include anti-muscarinic medication like Oxybutynin.

LOWER MOTOR NEURON BLADDER

  • Condition: Overflow incontinence due to sacral spinal cord injury/disorder (S1-S3).

  • Clinical signs include decreased anal tone, decreased perineal reflex, hind limb paresis, and inability to urinate voluntarily.

  • Bladder can be easily expressed, but if not cared for, may overflow causing incontinence due to incomplete emptying.

  • Goal is treating the underlying condition and teaching owners to express the bladder.

VOIDING DISORDERS

  • Two Major Categories:

    • Mechanical: Urethral obstruction, urolithiasis, neoplasia, prostatic disease, FLUTD.

    • Functional: Reflex dyssynergia, detrusor atony, dysautonomia, upper motor neuron bladder.

REFLEX DYSYNERGIA

  • Definition: Abnormal coordination of urethral sphincter relaxation and detrusor muscle contraction.

  • Often associated with middle-aged, large male dogs.

  • Symptoms may include urination in spurts, with incomplete bladder emptying.

  • Neurological examination is typically normal; urinary catheter passes easily.

  • Treatment often involves α1 antagonists like prazocin or tamsulosin to aid relaxation of sphincters.

Detrusor Atony

  • Distinction:

    • Neurogenic: Injury to sacral or pelvic nerves (LMN bladder).

    • Non-Neurogenic: Direct damage to detrusor tight junctions due to chronic distension or outflow obstruction.

  • Treatment involves maintaining bladder size, potential use of the cholinergic agent Bethanecol (if outflow obstruction isn't present).

DYSFUNCTIONAL DISORDERS

  • Dysautonomia: An idiopathic condition affecting various species, leading to signs of both sympathetic and parasympathetic dysfunction.

  • Significant features include:

    • Dilated, non-responsive pupils.

    • Dry mucous membranes.

    • Bradycardia and megasophagus.

    • Dysuria, urine retention, overflow incontinence.

  • Diagnosis: Based on clinical signs, response to pilocarpine, and Schirmer Tear Test for tear production.

UPPER MOTOR NEURON BLADDER

  • Characteristics:

    • Associated with spinal cord lesions from C1-L3.

    • May present with an inability to urinate voluntarily and urethral sphincter tone maintained.

  • Treatment may necessitate frequent catheterization to decompress bladder and prevent overflow incontinence. Medications like α1 antagonists can aid in relaxation during monitoring for hypotension.

PROSTATIC DISORDERS

  • Conditions include:

    • Benign prostatic hyperplasia.

    • Prostatic/ para-prostatic cysts.

    • Prostatitis.

    • Prostatic abscess.

    • Prostatic neoplasia.

    • Squamous metaplasia.

    • Perineal hernia associated with chronic tenesmus.

PROSTATE EXAMINATION

  • Normal Findings: Palpable at pelvic brim, a smooth bi-lobed structure measuring approximately 3-4cm. The median raphe is appreciable.

  • Abnormal Findings: Include enlarged, painful prostate with loss of symmetry; may not be palpably discerned beyond pelvic brim in severe cases.

BENIGN PROSTATIC HYPERPLASIA (BPH)

  • Most common prostate condition in entire male dogs, affecting over 90% by age eight.

  • Caused generally by hormonal changes leading to glandular hyperplasia and hypertrophy.

  • Clinical signs include dysuria, tenesmus, stranguria, hematuria, and reduced fertility.

PROSTATIC CYSTS

  • Small, often incidental, cysts may be detected on ultrasound within prostatic parenchyma that can later become infected.

  • Larger cystic structures around the prostate can develop from remnants of uterus masculinus and become perineal hernia in later stages.

BACTERIAL PROSTATITIS

  • Affects entire male dogs predominantly, and is more common than cystitis due to the blood-prostate barrier.

  • Clinical signs mirror those of other prostatic disorders including dysuria, tenesmus, and penile discharge.

PROSTATITIS DIAGNOSIS

  • Rectal exam to assess for enlargement and pain; consider performing a prostatic wash to gain fluid for analysis.

  • Ensure caution is maintained due to risk of prostatic abscess rupture.

PROSTATE NEOPLASIA

  • Types: Adenocarcinoma (24%), Urothelial cell carcinoma (51%), Mixed/undifferentiated carcinoma (22%).

  • Characterized as aggressive with metastasis commonly present at diagnosis. Mineralization of the prostate in neutered males suggests potential neoplasia.

TREATMENT DETOUR FOR NEOPLASIA

  • Options include NSAIDs for pain control, chemotherapy, complex surgical prostatectomy, and radiation therapy.

SQUAMOUS METAPLASIA

  • Transformation of columnar epithelial cells observed in chronic exposure to estrogen. Clinical signs include feminization effects.

  • Treatment involves removing the estrogen source, and potentially castrating affected animals.

CONCLUSION AND DISCUSSIONS

  • Reinforcement of understanding micturition mechanisms and disorders is critical for effective diagnostic and treatment approaches within veterinary medicine, particularly concerning prostatic disorders due to their prevalence and significant impact on male canine health.

QUESTIONS?