Drugs used to treat urinary disorders include antibiotics and antifungal medications for infections, diuretics for kidney failure, and a variety of other drugs for several other disorders.

Antibiotics

Antibiotic drugs are the basis of urinary tract infection treatment. Antibiotic treatment involves determining the type of bacteria present and choosing the appropriate drug. There are many types of antibiotics; your veterinarian will prescribe one that is excreted in an active form in the urine and is known to be effective against the particular bacteria present (see Drugs and Vaccines: Antibiotic Drugs Commonly Used to Treat Urinary Tract Infections in Dogs and Cats*).

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Antibiotic Drugs Commonly Used to Treat Urinary Tract Infections in Dogs and Cats* Drug Typical Antibacterial Activity Amoxicillin Staphylococci, streptococci, enterococci, Proteus Ampicillin Staphylococci, streptococci, enterococci, Proteus Amoxicillin/clavulanic acid Staphylococci, streptococci, enterococci, Proteus Cephalexin/cefadroxil Staphylococci, streptococci, Proteus, Escherichia coli, Klebsiella Ceftiofur Escherichia coli, Proteus Enrofloxacin Staphylococci, some streptococci, some enterococci, Escherichia coli, Proteus, Klebsiella, Pseudomonas, Enterobacter Gentamicin Staphylococci, some streptococci, some enterococci, Escherichia coli, Proteus, Klebsiella, Pseudomonas, Enterobacter Nitrofurantoin Staphylococci, some streptococci, some enterococci, Escherichia coli, Klebsiella, Enterobacter Tetracycline Streptococci, some activity against staphylococci and enterococci at high urine concentrations Trimethoprim/sulfa Streptococci, staphylococci, Escherichia coli, Proteus, some activity against enterococci and Klebsiella *Many of the drugs listed are not directly approved by the FDA for treatment of the bacteria listed. Veterinarians decide what drug and dosage to use for an animal based on their experience, published reports, and continuing education.

Many animals with recurrent urinary tract infections are treated with repeated courses of antibiotics. If the underlying cause of the infection is not found, the repeated courses of antibiotics can do more harm than good. Inappropriate treatment with the wrong antibiotic can cause bacteria to become resistant (see Drugs and Vaccines: Guidelines for the Use of Antibiotic Drugs). Chronic urinary tract infections from highly resistant bacteria are very hard to treat.

If episodes occur more than once or twice yearly, and the causes of the urinary tract infections cannot be found or corrected, longterm low-dose treatment with oral antibiotics may be necessary to prevent new episodes.

Antifungal Drugs

Although uncommon, fungal urinary tract infections occur in dogs and cats. Treatment involves removing any predisposing factors (excessive corticosteroids, urinary catheters) and giving antifungal drugs, with or without urinary alkalinization (see Drugs and Vaccines: Controlling Urine pH).

Controlling Urine pH
pH is the measure of how acidic or alkaline (basic) a substance is. Urine with abnormally high or low pH can contribute to the formation of certain types of kidney or bladder stones. In dogs, urine pH should be between 7 and 7.5. In cats, it should be between 6.3 and 6.6. Potassium citrate can be used to raise the pH, making it more alkaline (basic). Ammonium chloride or DL‑methionine can be used to lower the pH, making it more acidic.

Cystine-binding Agents

Cystinuria, with the formation of cystine kidney stones, is caused by an inherited disorder. Cystine kidney stones are dissolved with changes in the diet, urinary alkalinization or neutralization, and the use of cystine-binding agents. Once stones are dissolved, changes in the diet can help prevent them from coming back.

Diuretics

Diuretics are used to remove excess water from animals with swelling or volume overload, such as that which occurs with kidney failure. There are several classes of diuretics, grouped by the way they act in the body (see Drugs and Vaccines: Diuretics*). Loop diuretics are named because of their effect on the ascending loop of Henle in the kidney. Carbonic anyhdrase inhibitors work by decreasing the formation of carbonic acid, making more sodium bicarbonate, which takes water with it when it is excreted. Carbonic anhydrase inhibitors also enhance potassium excretion. Thiazide diuretics are infrequently used, but they may be given to animals that cannot tolerate the more potent loop diuretics. Thiazides can be combined with loop or potassium-sparing diuretics. They may also be used to treat diabetes insipidus, which affects the kidneys. Potassium-sparing diuretics do not cause the loss of potassium, which is beneficial in some conditions in which potassium levels may be low. These are usually used in combination with other diuretics, rather than alone. Osmotic diuretics keep water from being reabsorbed in the kidneys.

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Diuretics* Drug Chlorothiazide Dimethyl sulfoxide Furosemide Hydrochlorothiazide Mannitol Spironolactone *Many of the drugs listed are not directly approved by the FDA for treatment in all species. Veterinarians decide what drug and dosage to use for an animal based on their experience, published reports, and continuing education.

Other Drugs

Some angiotensin-converting enzyme (ACE) inhibitors (see Drugs and Vaccines: Angiotensin-converting Enzyme (ACE) Inhibitors), may be helpful in treating chronic kidney failure, and may reduce excess protein in the urine in some animals. Dimethyl sulfoxide (DMSO) has been used in dogs with amyloidosis with variable results.

Natural and synthetic hormones may help treat urinary incontinence (see Drugs and Vaccines: Drugs to Treat Urinary Incontinence*). For example, a nonsteroidal estrogen derivative that closely resembles estradiol has been effective in treating urinary incontinence in female dogs. Alpha-adrenergic agents may also be helpful for this condition.

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Drugs to Treat Urinary Incontinence* Drug Diethylstilbestrol Ephedrine Phenylpropanolamine Pseudoephedrine Testosterone cypionate Testosterone propionate *Many of the drugs listed are not directly approved by the FDA for treatment in all species. Veterinarians decide what drug and dosage to use for an animal based on their experience, published reports, and continuing education.

Muscle relaxants may help relieve urine retention due to tightening of the urethral muscles. Other drugs that may be tried include adrenergic antagonists or cholinergic agonists.

Last full review/revision July 2011 by Philip T. Reeves, BVSc, PhD, FACVSc; Jörg M. Steiner, DrMedVet, PhD, DACVIM, DECVIM-CA; Dawn Merton Boothe, DVM, PhD, DACVIM, DACVCP; Maya M. Scott, BS, DVM; Ian Tizard, BVMS, PhD, DACVM; Jozef Vercruysse, DVM, DEVPC