Phenylpropanolamine (PPA)

What is this medication for?

• Urethral sphincter mechanism incompetence (spay incontinence) — first-line medical therapy; retrograde ejaculation (3–4 mg/kg every 12 hours)
• Urethral sphincter hypotonus incontinence

How is it given?

Give exactly as your veterinarian prescribed — never change the dose or stop on your own unless your veterinarian has told you to.

• PPA is the pharmacologic backbone of canine spay-incontinence: it restores urethral closing pressure by alpha-adrenergic stimulation — response rates 74–92%, with SR formulations rescuing half of immediate-release failures.

What if I miss a dose?

• Give it as soon as you remember — unless it is almost time for the next dose (then skip the missed one; never double up).
• Call your clinic if you miss more than one dose in a row.

Side effects — what should I watch for?

Effects listed as common in this handout

• Restlessness, anxiety, irritability, loss of appetite (Common)
• Hypertension, unusually fast heart rate, urine retention (Dose-related)

Worth a phone call to your veterinarian

• Rare "stroke" reports at therapeutic doses (Idiosyncratic)

⚠️ Contact your veterinarian or an emergency clinic IMMEDIATELY if you notice

• Trouble breathing, collapse, seizures, severe vomiting or diarrhea, facial swelling, or pale gums

Before starting (or refilling), tell your veterinarian if your pet:

• has or has had: Hypertension, cardiac disease, glaucoma, prostatic hypertrophy, hyperthyroidism, diabetes mellitus
• has or has had: Human PPA stroke association led to its OTC-decongestant withdrawal — veterinary urethral use at lower doses continues with monitoring

• is pregnant, nursing, or used for breeding
• is taking any other medications, supplements, or flea/tick products, including:
  • MAOIs (selegiline, amitraz)
  • Other sympathomimetics, tricyclics
  • Antihypertensives
  • Halogenated anesthetics

Storage and handling

Room temperature. Chewable tablets (Proin) + SR capsules — keep out of pet reach (chewable = ingestion risk).

Good to know

• PPA is the pharmacologic backbone of canine spay-incontinence: it restores urethral closing pressure by alpha-adrenergic stimulation — response rates 74–92%, with SR formulations rescuing half of immediate-release failures.
• The estrogen alternatives (DES/estriol) and the Surgery options exist, but PPA-first is the standard algorithm; if it fails or causes agitation/high blood pressure → estriol (Incurin) or combination.
• Chewable Proin = common toxCall: 48 mg/kg ingestion caused V-tach + myocardial tissue death (recovered in 6 months) — high blood pressure/overheating/mydriasis are the tox signature; treat with alpha/beta blockade as needed.
• Monitor BP in senior patients — incontinence dogs are often older, and PPA is a pressor.