Urinary incontinence means leaking urine without control. In dogs, the most common reason the bladder fails to hold urine is urethral sphincter mechanism incompetence (USMI), a weakness of the muscle that keeps the urethra closed. It most often affects spayed female dogs, may become more noticeable in middle age and later, and typically shows up as leaking while a dog is asleep or lying down, with normal urination otherwise (Merck Veterinary Manual).
Veterinarians also prescribe urinary medications for related problems: making urine less acidic in dogs and cats that form calcium oxalate bladder stones, and relaxing the urethra in some pets with urethral spasm. Bayview Pharmacy compounds three of these as oral liquids, phenylpropanolamine, potassium citrate, and prazosin, as part of our veterinary compounding line, alongside pimobendan, trilostane, and ursodiol.
How does it work?
Phenylpropanolamine is a chemical relative of the body's own adrenaline-like messengers. It is an alpha-adrenergic drug reported to increase the tone of the urethra in dogs, the tube that carries urine out of the bladder (PROIN label).
Potassium citrate is an alkalinizing salt. Once the body processes it, urine becomes less acidic and carries more citrate. Citrate binds calcium, leaving less calcium free to combine with oxalate into crystals (Minnesota Urolith Center; Merck Veterinary Manual).
Prazosin is an alpha-blocker. In people it relaxes blood vessels and is used for high blood pressure (MedlinePlus). In pets, veterinarians use it as a smooth-muscle relaxant for the urethra when spasm is thought to be part of the problem (Veterinary Evidence).
What is it used for?
Leaking in spayed female dogs. Phenylpropanolamine is used to control urinary incontinence caused by weak urethral sphincter tone in dogs (PROIN ER label). Estriol, a hormone, is another approved option, and veterinarians sometimes combine phenylpropanolamine with an estrogen when one medication alone is not enough (Merck Veterinary Manual). Because leaking can also come from a urinary tract infection, nerve disease, or a malformation, your veterinarian looks for those causes as part of the diagnosis.
Calcium oxalate stones. Calcium oxalate bladder stones cannot be dissolved with medication or diet, so stones that cause problems are removed. Prevention focuses on diet, more water in the diet, and avoiding foods that make urine acidic, and veterinary consensus recommends considering potassium citrate for dogs and cats whose urine stays acidic (ACVIM consensus). Veterinarians may also use it to make urine less acidic in some dogs with urate stones (Merck Veterinary Manual).
Urethral spasm. Prazosin is one of the alpha-blocking medications veterinarians use for idiopathic functional urethral obstruction, also called reflex dyssynergia, a problem with the urethra relaxing during urination in dogs (Merck Veterinary Manual). Studies in male cats after a urinary blockage have not shown that it lowers the risk of another blockage within 30 days (Veterinary Evidence), so your veterinarian decides whether it fits your pet's situation.
How do the liquids compare to tablets?
The approved phenylpropanolamine products are flavored chewable tablets given twice daily and extended-release tablets given once daily (FDA). The extended-release tablets cannot be dosed safely in dogs under 10 pounds, because even the smallest tablet would exceed the labeled dose (PROIN ER label). A compounded flavored liquid is measured by oral syringe, so your veterinarian can prescribe an exact amount for a small dog or a dog that will not take a chewable. Potassium citrate is approved for people as extended-release tablets (UROCIT-K label), and Bayview prepares it as a 500 mg/mL oral solution measured to your pet's dose. Prazosin is approved for people as capsules (prazosin label), and Bayview prepares a 1 mg/mL liquid for small doses. When a pet needs a medication as a liquid that is not listed here, our custom oral suspensions page explains how that works.
How is it given?
All three are given by mouth. Shake suspensions well and measure each dose with the oral syringe provided, never a kitchen spoon. Potassium citrate is often given in food (Merck Veterinary Manual), and your veterinarian or pharmacist will tell you how to give each liquid. Your veterinarian sets the dose and schedule, which are specific to your pet. If you are asked to check urine pH at home with test strips, your veterinarian will explain when to test and what to record (Minnesota Urolith Center).
Side effects & safety
Phenylpropanolamine can raise blood pressure, and the approved labels advise caution in dogs with heart disease, high blood pressure, liver disease, kidney problems, diabetes, or glaucoma. Commonly reported effects include vomiting, poor appetite, weight loss, and increased thirst, so keep fresh water available. Restlessness, irritability, anxiety, and aggression have been reported, and post-approval reports include seizures, tremors, and loss of coordination (PROIN label; FDA).
Phenylpropanolamine and people. The veterinary labels state that it is not for human use and must be kept out of reach of children (PROIN label). FDA asked drug companies to stop marketing products containing phenylpropanolamine for people after it was linked to a risk of hemorrhagic stroke, or bleeding into the brain (FDA). If a person swallows it, contact a physician or Poison Control at 1-800-222-1222.
Potassium citrate can raise blood potassium and reduce appetite, and veterinarians lower the dose if either happens. It is used with caution in pets that are dehydrated or have kidney disease, diabetes, or hypoadrenocorticism (Addison's disease) (Minnesota Urolith Center). In people, potassium citrate is not used with high blood potassium, certain stomach and bowel conditions, or an active urinary tract infection (UROCIT-K label).
Prazosin lowers blood pressure. In people it can cause dizziness or fainting, most often after the first dose or a dose increase (MedlinePlus). Lethargy, diarrhea, and poor appetite were reported in one feline study (Veterinary Evidence).
A blocked cat is an emergency. A cat, especially a male cat, that strains to urinate or passes little or no urine needs veterinary care right away. Complete urinary obstruction can be fatal in less than 24 to 48 hours (Cornell Feline Health Center).
Which pets should not take it?
Phenylpropanolamine is used with caution in dogs with heart disease, high blood pressure, liver or kidney disease, diabetes, or glaucoma, and its use in breeding, pregnant, or nursing dogs has not been evaluated (PROIN label). It does not help leaking caused by nerve disease or malformations (PROIN ER label). Potassium citrate is used with caution in pets with kidney disease, dehydration, diabetes, or hypoadrenocorticism, and the dose is reduced if blood potassium climbs (Minnesota Urolith Center). Because prazosin lowers blood pressure, tell your veterinarian about any other medications your pet takes. Share your pet's full history and every medication and supplement so your veterinarian can decide whether a medication is appropriate.
How should it be stored?
Store as directed on the label, keep the container tightly closed, and keep all three medications out of reach of children and other pets. Store phenylpropanolamine in a secured place: the approved labels report that dogs have chewed through closed bottles of the flavored tablets and overdosed, and direct owners to keep it away from dogs, cats, and other animals (PROIN label; PROIN ER label). Do not use any medication after the beyond-use date, and ask your veterinarian or pharmacist how to dispose of leftovers.
Why is this compounded?
Approved phenylpropanolamine tablets come in set sizes, and some dogs are too small for them or will not take a chewable. Potassium citrate is approved for people as extended-release tablets, and prazosin as capsules. Bayview compounds flavored phenylpropanolamine liquids in 10, 25, and 50 mg/mL, potassium citrate as a 500 mg/mL oral solution, and prazosin as a 1 mg/mL suspension, plus other strengths to order, so your veterinarian can prescribe a measured liquid dose when an approved product is not suitable for your pet. The rest of what we compound for animals is in our compounded medications catalog.
Clinical details for prescribers
Regulatory status. Phenylpropanolamine, potassium citrate, and prazosin are not federally controlled substances; the PROIN, UROCIT-K, and prazosin capsule labels list no DEA schedule (PROIN label; UROCIT-K label; prazosin label). FDA-approved veterinary products for canine urinary incontinence include phenylpropanolamine chewable tablets (PROIN, NADA 141-324), phenylpropanolamine extended-release tablets (PROIN ER, NADA 141-517), and estriol tablets (INCURIN, NADA 141-325) (PROIN ER label; INCURIN label). Potassium citrate extended-release tablets (UROCIT-K) and prazosin capsules are FDA-approved for people. Bayview's preparations are compounded for an individual animal on a valid prescription within a veterinarian-client-patient relationship, as extralabel use under AMDUCA (FDA: AMDUCA); animal drugs compounded from bulk drug substances follow FDA's GFI #256 (FDA: Animal drug compounding).
Formulation and dosing. Phenylpropanolamine HCl flavored oral suspension 10, 25, or 50 mg/mL; potassium citrate oral solution 500 mg/mL; prazosin oral suspension 1 mg/mL; other strengths to order. Reported dosing: phenylpropanolamine 2 mg/kg PO every 8 to 12 hours (Merck Veterinary Manual); the PROIN chewable label gives 2 mg/kg twice daily and the PROIN ER label 2 to 4 mg/kg once daily with food (PROIN label; PROIN ER label). Potassium citrate: a starting dose of 75 mg/kg PO twice daily, adjusted in 20% steps toward a urine pH near 6.5 (Minnesota Urolith Center). Prazosin: 0.5 to 3 mg per dog PO every 8 to 12 hours for idiopathic functional urethral obstruction (Merck Veterinary Manual); feline studies after urethral obstruction used 0.25 to 0.5 mg per cat every 12 hours or 0.5 to 1 mg per cat once daily (Veterinary Evidence).
Counseling and clinical points:
- Hypertension is a labeled adverse reaction (19.5% with PROIN chewables; 12.6% at or above 160 mmHg with PROIN ER). The labels advise caution with pre-existing cardiac disease, hypertension, hepatic disease, renal insufficiency, diabetes, and glaucoma, and with sympathomimetics, tricyclic antidepressants, or MAO inhibitors (PROIN label; PROIN ER label).
- The PROIN ER label notes that phenylpropanolamine may mask incontinence due to urinary tract infection and does not help incontinence from neurologic disease or malformations. The INCURIN label likewise advises evaluating contributing factors before treatment (INCURIN label).
- Labeled adverse reactions for PROIN include restlessness, irritability, anxiety, and aggression; post-approval reports include seizures, tremors, ataxia, and deaths. Overdoses have followed dogs chewing through closed bottles of flavored chewables, so counsel secured storage for the flavored liquid as well (PROIN label).
- Not for human use. FDA requested that drug companies discontinue marketing products containing phenylpropanolamine because of hemorrhagic stroke risk in people (FDA).
- Calcium oxalate uroliths are not amenable to medical dissolution. ACVIM prevention centers on high-moisture diets, avoiding acidifying diets, and considering potassium citrate for persistently acidic urine (ACVIM consensus). The Minnesota Urolith Center describes its use mainly in calcium oxalate formers with consistently low urine pH (6 or below) (Minnesota Urolith Center).
- Have owners measure urine pH with pH paper about every 5 to 6 hours for 2 to 3 days to guide titration; reduce the dose by 20% for decreased appetite or serum potassium above 6.2 mmol/L, and use caution with dehydration, decreased kidney function, diabetes, and hypoadrenocorticism (Minnesota Urolith Center).
- Prazosin is an alpha-adrenergic antagonist; postural hypotension and syncope are described in human labeling (prazosin label). In male cats after urethral obstruction, a knowledge summary concluded prazosin does not reduce recurrent obstruction within 30 days; one retrospective study reported recurrence after 14 days post discharge in 24% of cats given prazosin versus 13% of cats not given it, and lethargy, diarrhea, and anorexia were reported in one prospective study (Veterinary Evidence).
Bayview compounds these when an approved product is not suitable for the patient. Account setup and ordering are covered on our for providers page.
References
- FDA: PROIN ER approval
- DailyMed: PROIN label
- DailyMed: PROIN ER label
- DailyMed: INCURIN label
- Merck Veterinary Manual: Disorders of micturition
- Merck Veterinary Manual: Controlling urine pH
- ACVIM consensus: Uroliths in dogs and cats
- Minnesota Urolith Center: Potassium citrate
- Cornell Feline Health Center: Feline lower urinary tract disease
- FDA: Phenylpropanolamine public health warning
- DailyMed: UROCIT-K label
- Veterinary Evidence: Prazosin in male cats
- MedlinePlus: Prazosin
- DailyMed: Prazosin capsules label
- FDA: AMDUCA
- FDA: Animal drug compounding
The medications on this page are compounded veterinary preparations and are not FDA-approved. This information is educational and is not a substitute for your veterinarian's instructions. Your veterinarian determines whether a medication is appropriate and sets the dose.
