furosemide
Furosemide (Lasix) is a loop diuretic (water pill) used to remove excess fluid caused by conditions like heart failure or kidney problems in cats and dogs. It’s commercially available as a tablet and liquid taken by mouth usually once or twice a day. There’s also an injection form, but it’s typically given by a veterinarian if your pet has more serious problems. The most common side effects are increased urination, thirst, and dehydration.
What is Furosemide for pets?
What is Furosemide for pets used for?
Liver problems in cats and dogs
Kidney problems in cats and dogs
High blood pressure in cats and dogs
How Furosemide for pets works
[EDITOR|DRUG_DISPLAY_NAME|||title]] is a loop diuretic (water pill). It works in the kidneys to remove water buildup in your pet’s body. Furosemide stimulates the kidneys to move more water into the urine, which is why your pet might urinate more often while they take this medication.
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What are the side effects of Furosemide for pets?
Common Side Effects
- Increased urination
- Diarrhea
- Constipation
- Vomiting
- Increased thirst
Other Side Effects
- Hearing problems
- Balance problems
Serious Side Effects
- Dehydration: less energy, dry nose, sunken eyes, changes to their gums or saliva, low appetite, rapid heartbeat
- Electrolyte imbalances: rapid heartbeat, collapsing, weakness, nausea or vomiting, seizures, coma, high blood pressure
The following side effects have also been reported
Side effects that you should report to your care team as soon as possible:
- Allergic reactions—skin rash, itching, hives, swelling of the face, lips, tongue, or throat
- Dehydration—increased thirst, dry mouth, feeling faint or lightheaded, headache, dark yellow or brown urine
- Hearing loss, ringing in ears
- High blood sugar (hyperglycemia)—increased thirst or amount of urine, unusual weakness or fatigue, blurry vision
- Low blood pressure—dizziness, feeling faint or lightheaded, blurry vision
- Low potassium level—muscle pain or cramps, unusual weakness or fatigue, fast or irregular heartbeat, constipation
Side effects that usually do not require medical attention (report to your care team if they continue or are bothersome):
- Burning or tingling sensation in hands or feet
- Constipation
- Diarrhea
- Dizziness
- Headache
Pros and cons of Furosemide for pets
Pros
Comes in a tablet and a liquid
Starts working within an hour
Works well to remove water out of the body
Cons
Commonly causes your pet to urinate more frequently
Might require frequent monitoring for labs and side effects
Pharmacist tips for Furosemide for pets
You might want to give furosemide to your pet in the morning since it will make them urinate more often. Giving this medication at night might lead to frequent bathroom trips that might keep both you and your pet awake.
Unless your vet suggests your pet should have water restrictions, make sure they have clean, fresh water. Since furosemide makes them urinate more, they need to drink more to stay hydrated.
If your pet gets too much furosemide, contact your vet or a pet poison helpline right away. Too much of this medication can cause dehydration and damage their organs. Watch for signs like extreme tiredness, excessive thirst, urinating less, or reduced appetite.
It is not fully understood if furosemide is safe for pregnant or nursing pets. Talk to your vet about the risks and benefits of giving this medication to your pet if they are pregnant, nursing, or if you plan to breed them.
If your pet is taking the liquid or compounded version of furosemide, use the provided calibrated safety dropper to measure the dose. Don’t use household spoons to measure the dose for your pet since not all spoons are the same size.
If your pet is taking a compounded version of furosemide, follow the vet's or pharmacist's advice about storage and dosing.
Frequently asked questions about Furosemide for pets
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What are the risks and warnings for Furosemide for pets?
Furosemide can cause some serious health issues. This risk might be even higher for certain pets. If this worries you, talk to your veterinarian about other options.
Dehydration
Risk factors: History of dehydration | Kidney problems
Furosemide pulls water from the body into the urine, so your pet might get dehydrated if the dose is too high or if they are at risk for dehydration. Pets already dehydrated or not urinating are more at risk because this medication can make dehydration worse. Watch for signs of dehydration, including less energy, dry nose, sunken eyes, changes to their gums or saliva, and low appetite.
Electrolyte imbalances
Risk factors: Dehydration | Vomiting | Diarrhea | Pets taking digoxin | Pets with a history of electrolyte imbalances
Furosemide removes water by affecting electrolytes in the kidney. This can lower levels of potassium, sodium, calcium, and magnesium. Your vet should monitor your pet for electrolyte imbalances. Early signs of electrolyte imbalances include increased thirst, excessive tiredness, urinating less, heart rhythm changes, and extreme nausea, vomiting, or diarrhea. If you notice any of the signs above, contact your vet right away.
Higher blood sugar
Risk factors: Diabetes
Furosemide can raise blood sugar levels in all pets. If your pet has diabetes, this medication could raise their blood sugar, causing them to need more insulin than usual. If your pet does not have diabetes, this medication could cause them to get diabetes if they have risk factors for diabetes, such as latent diabetes. Talk to your vet if you notice any changes
Hearing problems
Risk factors: Giving higher doses of furosemide
Furosemide can cause damage to the ear, which can lead to hearing loss. Hearing damage happens at higher than recommended doses. Contact your vet if you believe your pet has lost its hearing while taking this medication.
Furosemide dosage forms
| Dosage | Quantity | Price as low as | Price per unit |
|---|---|---|---|
| 40mg/5ml | 30 ml | $5.06 | $0.17 |
Typical dosing for Furosemide for pets
The dose of furosemide is based on your pet’s weight. It also depends on how your pet reacts to this medication or the condition being treated.
Cats can be more sensitive to furosemide and might require a lower dose than dogs.
The dose for furosemide is usually between 1 mg/kg to 5 mg/kg by mouth every 12 to 24 hours.
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Furosemide contraindications for pets
Certain liver problems
Pregnant animals
Current electrolyte imbalances
What are alternatives to Furosemide for pets?
Liver problems in cats and dogs
Kidney problems in cats and dogs
High blood pressure in cats and dogs
Congestive heart failure (CHF) in dogs and cats
High blood pressure in dogs and cats
Kidney problems in dogs and cats
Furosemide images
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References
Best studies we foundAcierno, M. J., et al. (2018). ACVIM consensus statement: Guidelines for the identification, evaluation, and management of systemic hypertension in dogs and cats. Journal of Veterinary Internal Medicine.
Allen, L. V., Jr. (2017). Furosemide 10 mg/mL oral suspension. U.S. Pharmacist.
American College of Veterinary Pharmacists. (n.d.). Furosemide.
Ames, M. K., et al. (2013). Effect of furosemide and high-dosage pimobendan administration on the renin-angiotensin-aldosterone system in dogs. American Journal of Veterinary Research.
Center, S. A. (2024). Portal hypertension and ascites in small animals. Merck Manual Veterinary Manual.
Chetboul, V., et al. (2017). Short-term efficacy and safety of torasemide and furosemide in 366 dogs with degenerative mitral valve disease: The TEST study. Journal of Veterinary Internal Medicine.
Dowling, P. M. (2024). Diuretics used to treat urinary disease in animals. Merck Manual Veterinary Manual.
Gordon, S. G., et al. (2024). Diuretics for use in animals. Merck Manual Veterinary Manual.
Keene, B. W., et al. (2019). ACVIM consensus guidelines for the diagnosis and treatment of myxomatous mitral valve disease in dogs. Journal of Veterinary Internal Medicine.
Kittleson, M. D. (2024). Heart failure in dogs and cats. Merck Manual Veterinary Manual.
Merck Sharp & Dohme Corp. (2024). Salix- furosemide tablet [package insert]. DailyMed.
MWI. (2023). Furosemide 1%- furosemide syrup [package insert]. DailyMed.
Plumb’s Veterinary Medication Guides. (2020). Furosemide.
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