Therapeutic diagnosis of atony of the detrusor muscle in a dog – case report

The urinary bladder is composed of layers of smooth muscle, known as the detrusor muscle. Urination occurs through the "detrusor reflex," which causes contraction of the bladder and relaxation of the urethra. Bethanechol, a parasympathomimetic drug, is indicated for dogs with hypocontractility or atonia of this muscle, aiding in bladder emptying. This report presents the case of a 9-year-old, 13.5 kg, spayed mixed-breed female dog, who experienced pollakiuria for three months. Initial supplementary exams revealed no significant alterations, except for a full and firm bladder upon palpation. Cystitis was identified, but the dog still could not urinate properly after the condition was resolved. Bethanechol was then administered as a diagnostic and therapeutic alternative, resulting in significant improvement. Thus, based on the response to the medication and the absence of other findings, it was concluded that the patient had detrusor muscle atonia. However, 23 days after the resolution of the condition, there was a worsening of clinical symptoms, necessitating more in-depth diagnostic evaluation to define the primary cause of the condition. Computed tomography helped exclude potential differential diagnoses related to spinal cord conditions. Nonetheless, more specific supplementary exams, such as magnetic resonance imaging and cerebrospinal fluid (CSF) analysis, would be necessary to reach a definitive diagnosis. This case highlights the importance of a comprehensive and continuous diagnostic approach for complex and recurrent urinary conditions in dogs.