Furosemide (Lasix®) in Dogs and Cats

Treating Congestive Heart Failure and Other Dog and Cat Diseases with Furosemide

At The Vet's Office

What is Furosemide (Lasix®)?

Furosemide (Lasix®) is a frequently used medication in both dogs and cats. It is probably the most powerful diuretic available for use in the canine and feline. Furosemide is a cornerstone in the treatment of congestive heart failure in both dogs and cats.

It is also used to treat pulmonary edema (fluid in the lungs) resulting from causes other than heart failure as well as a number of other canine and feline diseases and conditions.

How Does Furosemide Work?

Furosemide is a diuretic, a medication that is used to help reduce the amount of fluid in the body by increasing the volume of urine passed.

More specifically, it is referred to as a loop diuretic, because furosemide acts on the loop of Henle (part of the kidney) to stop the kidney from reabsorbing sodium and chloride. Because sodium and chloride are not reabsorbed, more water passes in the urine and ultimately increases the volume of urine produced.

What Are the Indications for Using Furosemide in Dogs and Cats?

There are several diseases and conditions in dogs and cats which furosemide can help treat.

  • Furosemide is almost always used as a primary line of treatment in cases of congestive heart failure in dogs and cats. It is used to remove the excess fluid build-up in the lungs and other areas of the body that accompany congestive heart failure in dogs and cats.
  • Furosemide is also used to treat pulmonary edema (fluid in the lungs) that occurs as a result of non-cardiogenic (not heart-related) disease.
  • Furosemide may be used to treat kidney disease when the kidneys have shut down and stopped producing urine.
  • Similarly, furosemide may be used to treat kidney disease caused by elevated calcium levels (hypercalcemic or hypercalcuric nephropathy.)
  • Hyperkalemia (elevated blood potassium levels) may require furosemide to correct the imbalance.
  • Furosemide is sometimes also used to treat high blood pressure in dogs and cats.

What Are the Potential Side Effects of Using Furosemide in Pets?

Pet owners administering furosemide to their dogs or cats should be aware of the potential side effects of the medication.

Furosemide can cause imbalances of the electrolytes in the blood stream.These electrolyte imbalances may result in signs such as:

  • Drinking excessive amounts of water (i.e being thirsty)
  • Lethargy
  • Depression
  • Restlessness
  • Reduced urination
  • GI distress (vomiting, diarrhea, etc.)
  • Elevated heart rate
  • Coma
  • Seizures

Administering furosemide may also result in excessive water loss and may cause dehydration. Blood pressure should also be monitored while your pet is receiving furosemide.

In Summary

Furosemide (Lasix®) is used in dogs and cats to treat a variety of issues, including congestive heart failure and pulmonary edema. Pet owners administering furosemide should be aware of the potential side effects and alert their veterinarian if an adverse reaction to the medication is suspected.

Please note: this article has been provided for informational purposes only. If your pet is showing any signs of illness, please consult a veterinarian as quickly as possible.