Effect of Phenylpropanolamine and Pseudoephedrine on the Urethral Pressure Profile and Continence Scores of Incontinent Female Dogs

Abstract

Background: Traditionally, treatment of urinary incontinence in spayed female dogs has been to increase urethral sphincter tone with estrogen compounds or α‐agonists. Phenylpropanolamine (PPA) is the most frequently used α‐agonist for this condition, but increased cost and decreased availability of PPA as an over‐the‐counter medication have prompted interest in alternative therapies that may provide the same degree of efficacy. Pseudoephedrine (PD), an α‐agonist and stereoisomer of ephedrine, is more cost‐effective and available without a prescription. Hypothesis: PD will not differ from PPA in its effects on urodynamic variables and owner‐reported continence scores or in observed adverse effects. Animals: Nine spayed female dogs with a history of urinary incontinence drawn from the clinical patient population at the Veterinary Teaching Hospital at The Ohio State University. Methods: A randomized, double‐blind crossover study evaluating changes in urodynamic variables, owner‐reported continence score, and adverse effects in dogs treated with 1.5 mg/kg PO q8h PPA or PD. Results: Changes in maximum urethral closure pressure and functional area after PPA therapy were significantly higher than after PD therapy. There was no change in the functional profile length after either treatment. There was a significant increase in the continence score after PPA therapy, but not after PD therapy. More adverse effects were observed in dogs treated with PD than with PPA. Conclusions and Clinical Importance: Although some dogs clinically improved, lack of statistically significant changes in urodynamic variables and owner perception of continence as well as the increased incidence of adverse effects make PD a less satisfactory alternative to PPA for the treatment of urinary incontinence in female dogs.