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Inability to Urinate in Dogs

Functional Urinary Retention in Dogs

Functional urinary retention in dogs refers to the incomplete emptying of urine without any obstruction in the urinary tract. It occurs due to an issue with the normal function of the organ. Complications from this condition may include lower urinary tract infections, bladder or urethral rupture, and permanent damage to the detrusor muscle, which is responsible for contracting and pushing urine out of the bladder. This condition is more prevalent in male dogs than in females.

Symptoms and Types

  • Palpably distended urinary bladder
  • Ineffective, frequent attempts to urinate without success
  • Weak, attenuated, or interrupted urine stream
  • Frequent leakage of urine due to bladder fullness
  • Abdominal distension, abdominal pain, or signs of postrenal azotemia may occur in rare cases or with urinary tract rupture
  • Muscular problems associated with urination may be caused by recurrent urinary tract infections

Causes

Causes of functional urinary retention in dogs include:

  • Hypercontractility of the urinary bladder detrusor muscle (detrusor atony), often developing after acute or chronic urinary bladder overdistension, with many dogs having a history of nervous system dysfunction or prior urinary blockage.
  • Electrolyte disturbances such as hyperkalemia, hypokalemia, hypercalcemia, or hypocalcemia.
  • Pelvic nerve lesions.
  • Lesions of the sacral spinal cord, including congenital malformations, cauda equina compression, lumbosacral disk disease, and vertebral fractures/dislocations, resulting in a flaccid, overdistended urinary bladder with weak outlet resistance.
  • Lesions of the suprasacral spinal cord, such as intervertebral disk protrusion, spinal fractures, and compressive tumors, leading to a distended, firm urinary bladder that is difficult to express or empty manually.
  • Dogs with neuropathy, sacral lesions, suprasacral spinal lesions, or midbrain disorders may also experience detrusor-urethral dyssynergia, where the contraction of the detrusor muscle and the relaxation of the urethra are not coordinated.
  • Decreased detrusor muscle contraction (detrusor atony) with urine retention is characteristic of dysautonomia, a disorder affecting the autonomic nervous system, observed in certain geographic regions of the United States.
  • Some dogs with Cushing’s disease may exhibit increased urination (polyuria), urinary bladder distention, and mild urine retention due to excessive levels of steroids produced by the adrenal glands.
  • Functional urinary obstruction may result from previous pelvic or urethral surgery, anticholinergic medications affecting normal nerve actions, or excessive urethral resistance, typically attributed to smooth or striated muscular components of the urethra (urethrospasm), observed after urethral obstruction or surgery, urethral or pelvic inflammation, or prostatic disease.

Diagnosis

Diagnosing functional urinary retention in dogs involves taking a detailed history of the dog’s health, noting the onset of symptoms, and any potential incidents that may have contributed to the condition. A comprehensive examination includes a complete blood profile, including a chemical blood profile, complete blood count, and urinalysis to detect signs of urinary tract infection or inflammation.

A neurological examination assesses the lower spine, evaluating peripheral nerve function through anal tone, tail tone, and perineal reflexes. Urethral catheterization may be necessary to rule out urethral obstruction, which should allow the catheter to pass easily if there is no blockage.

Imaging techniques such as myelography, epidurography, or computed tomography (CT scans) help identify spinal lesions indicating a neurological cause. Additionally, injecting a radiocontrasting agent into the body allows visualization of urine flow from the kidneys through the urethral tract via X-ray.

Given the various potential causes, veterinarians typically employ differential diagnosis, ruling out common causes until the underlying disorder is identified and treated accordingly. Possible causes considered include extramural urethral compression, oliguria, anuria, urinary tract rupture, physical obstruction, lesions above the spine or on the sacrum affecting urinary signals, loss of detrusor muscle coordination, and complications from recovering urinary obstruction, such as re-obstruction or detrusor weakness. The characteristics of the urinary bladder (distended, firm, or flaccid) and resistance to manual expression aid in determining the likely cause of the condition.

Treatment

Treatment for functional urinary retention in dogs typically involves inpatient care until normal urinary function is restored, unless a severe underlying condition is present. Specific treatment includes identifying and treating urinary tract infections if present, addressing primary disorders such as electrolyte disturbances and neurologic lesions, and managing associated complications such as azotemia, electrolyte imbalances, and acid-base disturbances.

In cases where complete voiding function does not return, ongoing management of the dog’s urinary health is necessary. This may involve frequent manual compression to release urine and intermittent or indwelling urinary catheterization to maintain urine flow and prevent bladder enlargement.

Regular urinalysis is recommended to monitor for urinary tract infections in dogs diagnosed with chronic urine retention. This proactive approach helps in early detection and management of any urinary issues that may arise.

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