In a multicenter, blinded, controlled study of female dogs older than 1 year of age with unconscious urination, 86% remained free of signs 28 days after initiation of treatment with phenylpropanolamine at 1 mg/kg PO q 8 hrs compared with 33% of dogs given placebo. Adverse side effects were not observed at this dose.

Care was taken to exclude dogs with urinary tract infection and those with conditions causing polyuria and polydipsia. The average patient in this study was 9 years old, weighed 24 kg, and had been spayed 6 to 7 years earlier.

COMMENTARY: This study confirms the efficacy of phenylpropanolamine for urethral incompetence in spayed female dogs but also emphasizes the necessity of urinalysis before treatment to check for urinary tract infection and dilute urine, both common causes of treatment failure.

Evaluation of phenylpropanolamine in the treatment of urethral sphincter mechanism incompetence in the bitch. Scott L, Leddy M, Bernay F, Davot JL. J Small Anim Pract 43:493-496, 2002.