A diuretic is a class of drug used to rid your pet's body of excess water and sodium through the urine. Diuretics are often prescribed when there is fluid buildup in your pet's body. Diuretics work by decreasing the absorption of fluid and/or electrolytes from the kidneys. Diuretics can be used for any disease where fluid can accumulate, such as heart or lung disease, or even in the brain after a head injury. If your pet has congestive heart failure, diuretics are often the first drugs prescribed. Other diseases where diuretics may be used include liver disease, certain kidney diseases, high blood pressure, or conditions where fluid or edema builds up in the tissues, even cancer.
Diuretics will typically cause a loss of retained fluid and certain electrolytes (i.e. sodium and potassium) from your pet's body, which may result in weight loss. Due to the effect of diuretics on bodily fluids, a drop in blood pressure may also occur. Diuretics even at normal doses occasionally can cause mild dehydration; therefore it is very important to maintain your pet's fluid and electrolyte intake when giving these medicines to avoid excessive thirst.
There are three major categories of diuretics: thiazide diuretics (hydrochlorothiazide), loop diuretics (Furosemide), and potassium sparing diuretics (Spironolactone). Each of these diuretics work in a different area of the kidney to produce the desired effect. One unique diuretic called Mannitol is an osmotic diuretic that is excreted through the kidneys along with excess fluids and electrolytes. Spironolactone inhibits the effect of aldosterone, a hormone that causes the tubules of the kidneys to retain salt and water. This increases the excretion of potassium. Furosemide is a potent loop diuretic that works by blocking the reabsorption of salt and fluid in the kidney tubules, causing an increase in urine output.
Although diuretics given to pets are often the same drugs used in human medicine, dosages will vary greatly from those taken by people, so it is best not to use prescriptions for people in pets, unless directed by your veterinarian.
Diuretics are generally safe when used as directed, but they do have side effects. Side effects or signs of toxicity may include dehydration accompanied by excessive thirst and urination, or electrolyte imbalances due to shifts in body sodium, potassium, and calcium. These electrolyte imbalances are often accompanied by weakness, drowsiness, restlessness, dizziness, stumbling, and muscle cramps or pain. If your pet is allergic to sulfa antibiotics, the diuretic Furosemide or hydrochlorothiazide should not be used. Spironolactone should be avoided in pets being treated for Cushing's Disease or Addison's Disease. Diuretics should be also used with caution when pre-existing liver disease or kidney disease is present, and should not be used at all in pregnant or nursing animals.
Since drug interactions may occur, pet owners should always consult with their veterinarians before giving vitamins or supplements. Most general multivitamins, Omega 3 fatty acids, probiotic, and enzyme products are fine to use in pets on diuretic therapy, but it always is recommended to check with your veterinarian first.
Certain Western herbs may be considered for use alongside of or instead of diuretic therapies. One of the most common herbs used is dandelion. Other homeopathic remedies including the remedy apis mellifica also may be considered in certain cases. For any pet on diuretic therapy, it is probably best to consult with a holistic veterinarian before considering using herbal or homeopathic alternative therapies.