Comparison of terazosin and prazosin for treatment of vesico‐urethral reflex dyssynergia in dogs

Abstract

Nineteen dogs with vesico-urethral reflex dyssynergia (VURD) were treated with prazosin or terazosin 0.5 mg/kg twice daily to compare efficacy and side effects. Dogs were referred because of signs of (partial) urethral obstruction. Physical examination, abdominal ultrasonography, urinalysis and a radiographic contrast study of bladder and urethra (urethrocystography) were routinely performed. If no mechanical causes of obstruction or disease of the distal urinary tract were observed, the diagnosis VURD was presumed and the dogs were included in our study. Follow-up information was obtained from owners or referring veterinarians. Significantly more side effects were seen in the dogs treated with terazosin (n=14; 93 per cent) compared with the dogs treated with prazosin (n=5; 20 per cent; P=0.002). Effects of the treatment were comparable between prazosin and terazosin. Labradors and dogs that were castrated surgically had a significant better survival (P<0.01) compared with other breeds and animals that were castrated chemically. There was a moderate to good effect in 60 per cent of the dogs treated with prazosin, and in 64 per cent of the dogs treated with terazosin.

Effectiveness of manual bladder expression in paraplegic dogs

“…22 Alternatively, alpha-adrenergic blockade with sympatholytic compounds such as prazosin or phenoxybenzamine aiming to cause urethral sphincter relaxation to be used in combination with parasympathomimmetic compounds could be advantageous when dealing with an upper motor neuron bladder. [23][24][25] A sacral nerve root stimulator is available for efficient bladder emptying in dogs with spinal cord injury and indicated for chronically incontinent dogs. 26 At 3 weeks after implantation, 8 out of 9 dogs had a voiding efficiency ranging from 92-99%, a clear improvement on the mean of 49% achieved in this study with manual bladder expression.…”

Bladder and Bowel Management in Dogs With Spinal Cord Injury

“…Terazosin, a long-acting selective α-1 adrenoreceptor blocking molecule has been used to treat vesico-sphincter dyssynergia in spinal cord-injured male humans and reduced bladder outlet obstruction (59) but causes side effects such as collapse and has not been reported in clinical papers since 2002. In dogs, terazosin has been used to treat vesico-urethral reflex dyssynergia but not in the context of spinal cord injury and showed side effects in 93% of the cases (60). Similarly, tamsulosin is also a α-1 adrenoreceptor blocking molecule with higher affinity that terazosin (61) but has not been trialed after spinal cord injury in dogs.…”

Pathophysiology, Clinical Importance, and Management of Neurogenic Lower Urinary Tract Dysfunction Caused by Suprasacral Spinal Cord Injury

“…For instance, a 20%, or 2.7 cmH 2 O, reduction in urethral pressure was noted in some tests, but the clinical importance of this apparently small effect is unknown; similar experiments in conscious healthy male cats also detected considerable variation in recorded pressures and very few consistent changes in urethral pressures associated with phenoxybenzamine or diazepam administration . On the other hand, there is some weak experimental evidence in male cats supportive of the putative urethral relaxation effect of alfuzosin, as well as evidence supporting the use of prazosin in reducing urethral pressure in nonsedated healthy dogs and terazosin in treating dogs with reflex dyssynergia …”