Furosemide (Lasix®) for Dogs and Cats

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Overview of Furosemide (Lasix®) for Dogs and Cats

  • Furosemide, commonly known as Lasix®, is used to reduce fluid accumulation and prevent further edema from forming. It is primarily used to treat heart failure and pulmonary edema in dogs and cats.
  • Some medical conditions are characterized by excessive retention of sodium (salt) and water. One good example is congestive heart failure where fluid (edema) accumulates in the lungs and body cavities. To prevent excessive retention of fluid, diuretic drugs are often used.
  • Furosemide is a loop diuretic drug, meaning that it works on the area of the kidney called Henle's loop. This drug prevents the absorption of chloride, sodium, potassium and water, leading to an increased volume of urine. This assists the kidneys in removing excessive fluid.
  • Furosemide is most often used in the treatment of heart failure. It is a potent diuretic drug. The drug is called frusemide in some parts of the world.
  • Furosemide is a prescription drug and can only be obtained from a veterinarian or by prescription from a veterinarian.
  • Brand Names and Other Names of Furosemide

  • This drug is registered for use in humans and animals.
  • Human formulations: Lasix® (Hoechst Marion Roussel), Salix®, Disal® and various generics
  • Veterinary formulations: Lasix® (Hoechst), Diuride® (Anthony) and various generics
  • Uses of Furosemide for Dogs and Cats

  • Furosemide is used to reduce fluid accumulation and prevent further edema from forming. It is primarily used to treat heart failure and pulmonary edema (lung fluid).
  • It is also used to treat some electrolyte imbalances, such as high calcium and high potassium levels, because the diuretic effect improves elimination of these ions.
  • Furosemide can also be used to stimulate urine output. 
  • Precautions and Side Effects

  • While generally safe and effective when prescribed by a veterinarian, furosemide can cause side effects in some animals.
  • Furosemide should not be used in animals with known hypersensitivity or allergy to the drug.
  • Furosemide should be avoided in animals with kidney impairment, dehydration, specific electrolyte abnormalities, diabetes or liver disease whenever possible.
  • Furosemide may interact with other medications. Consult with your veterinarian to determine if other drugs your pet is receiving could interact with furosemide. Such drugs include theophylline, corticosteroids, digitalis and aspirin.
  • Adverse effects include electrolyte disturbances, low blood potassium, dehydration and potential kidney effects.
  • Hearing loss and anemia have been reported when animals are given very high doses of furosemide.
  • How Furosemide Is Supplied

  • Furosemide is available in 12.5 mg, 20 mg, 40 mg, 50 mg and 80 mg tablets.
  • Furosemide is available in 8 mg/ml and 10 mg/ml solution and 10 mg/ml and 50 mg/ml injectable form.
  • Dosing Information of Furosemide for Dogs and Cats

  • Medication should never be administered without first consulting your veterinarian.
  • Furosemide can be administered as an oral tablet, oral liquid, and as an injectable drug. A constant rate infusion (CRI) may be administered for severe disease situations in hospitalized patients.
  • In dogs, furosemide is dosed at 1 to 3 mg per pound (2 to 6 mg/kg) one to four times per day.  
  • In cats, the dose is 0.5 to 2 mg per pound (1 to 4 mg/kg) one to three times daily.
  • The duration of administration depends on the condition being treated, response to the medication and the development of any adverse effects. Be certain to complete the prescription unless specifically directed by your veterinarian. Even if your pet feels better, the entire treatment plan should be completed to prevent relapse or prevent the development of resistance.
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