Functional urinary retention refers to the inability of a dog to completely empty its bladder, without any obstruction in the lower urinary tract. In other words, functional urinary retention is the incomplete emptying of the urinary bladder (voiding), which is not associated with physical blockage of the lower urinary tract (known as “urinary obstruction”). "Functional" refers to a problem with normal action of an organ.
Among various causes of functional urinary retention is neurogenic disruption of normal innervation of the micturition(urination) reflex by spinal cord disease. Depending on the location of spinal cord disease, there may be several different clinical presentations. Other less common causes of functional urinary retention include reflex dyssenergia, bladder atony (weakness/loss of coordination) from prolonged overdistention, and side effects of medications.
Common signs associated with functional urinary retention include
Palpably distended urinary bladder
Ineffective, frequent, attempts to urinate without success
Urine stream may be weak, attenuated, or interrupted
Bladder may be so full that it frequently leaks urine
Abdominal distension, abdominal pain, or signs of postrenal azotemia may predominate in rare cases or with urinary tract rupture
Recurrent urinary tract infections may have caused muscular problems associated with urinating
This condition is more common in male dogs than their female counterparts.