Furosemide for Dogs: A Treatment for Congestive Heart Failure
Key takeaways:
Furosemide (Lasix, Salix) is a diuretic, or “water pill,” that’s used to treat congestive heart failure and other conditions in dogs.
Furosemide works by removing fluid from the body by increasing urine production.
The potential side effects of furosemide include increased urination, gastrointestinal effects, and dehydration.
Table of contents
Furosemide (Lasix, Salix) is a diuretic, or “water pill,” that’s used to treat a variety of medical conditions in dogs. If your veterinarian prescribes furosemide for your dog, it’s because they suspect that your dog has extra fluid somewhere in their body. Furosemide will remove that excess fluid, helping your dog to feel better.
Below, learn how furosemide works for dogs and the best way to give it to your pup.
Furosemide for dogs at a glance
Common names | Furosemide (Lasix, Salix) |
What it treats | Heart failure, liver disease, kidney disease, and high blood pressure |
How it comes (forms) | Tablets, oral liquid, injection |
How it’s given (dosage) | Once or twice a day, depending on the dog’s symptoms and weight |
Common side effects | Increased urination, drinking more water than usual, vomiting, diarrhea, dehydration |
Cost |
What is furosemide for dogs and how does it work?
Furosemide is the most commonly used diuretic for pets. Furosemide affects the kidneys, triggering them to remove fluid from the bloodstream. That fluid is then released in the form of urine. By increasing how much a dog urinates, furosemide can clear excess fluid from their body.
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Furosemide is available as a brand-name medication for humans (Lasix) and pets (Salix). It is also available as a generic medication.
What is furosemide used for in dogs?
Veterinarians often treat dogs with congestive heart failure with furosemide to remove fluid in their lungs or belly.
A diseased heart struggles to move blood throughout the body, allowing fluid to accumulate in the lungs and/or belly. This fluid buildup impacts a dog’s ability to breathe and can make it more difficult for them to get enough oxygen. Furosemide removes built-up fluid, helping dogs with heart failure to breathe more easily.
Furosemide is also used to treat other conditions, such as:
Liver disease
Kidney disease
High blood pressure
High levels of calcium (hypercalcemia)
How is furosemide given to dogs, and what is the recommended dosage?
Most commonly, your dog will take furosemide by mouth as a tablet. You’ll usually give furosemide once or twice a day, depending on your dog’s needs. The tablet is the most commonly used form, but liquid furosemide is also an option. You can give furosemide to dogs with food or on an empty stomach.
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Your dog’s exact furosemide dosage will depend on their weight and the severity of their disease. Dogs who have severe heart disease may need a high dosage of furosemide. Dogs who have a milder case may only need a low dosage. You will work together with your veterinarian to find the best furosemide dosage for your dog.
In an emergency, your veterinarian may give your dog a furosemide injection. This could accompany other emergency treatment, such as hospitalization and oxygen therapy.
What should you do if your dog misses a dose of furosemide?
If your dog misses a dose of furosemide, give them the missed dose as soon as you remember. If it’s almost time for their next dose, skip the missed dose. Then, give them the next dose at the regularly scheduled time. Do not give your dog two doses of furosemide at once.
What are the common side effects of furosemide in dogs?
Furosemide can cause several side effects in dogs. Increased urination is the most common side effect of furosemide, but that’s what you want. Your dog may ask to go outside more often or release larger amounts of urine at one time. Though, some dogs taking furosemide may have accidents and urinate inside.
To make up for their increased urination, dogs also tend to drink more water while taking furosemide. Be sure your dog has access to fresh water at all times to reduce the risk of dehydration.
Other furosemide side effects to watch out for include:
If you notice any of these effects, contact your veterinarian for guidance. The likelihood of side effects usually depends on the dosage, with higher dosages increasing the risk. Giving your dog the lowest effective dosage (as your veterinarian recommends) will lower the risk of side effects.
What are the most serious risks of furosemide for dogs?
Furosemide removes fluid from your dog’s body. While that’s usually what you want, taking too much furosemide can cause serious dehydration and electrolyte changes. If your dog shows severe signs of illness, such as weakness or fainting, seek veterinary care as soon as possible.
In rare cases, very high doses of furosemide may cause hearing loss in dogs. Fortunately, this does not usually happen with doses regularly prescribed by veterinarians.
Does furosemide interact with any other dog medications?
Furosemide can interact with other medications, including:
Insulin
Benazepril
Antiseizure medications such as phenobarbital
Some antibiotics
Combining furosemide with any of these medications may increase the risk of side effects or interfere with the benefits of one or both medications.
Be sure that your veterinarian knows what medications your dog is taking. This includes over-the-counter medications and supplements. This will help them lower the risk of harmful interactions.
Frequently asked questions
Yes, furosemide will help your dog breathe better. Heart failure causes fluid buildup in a dog’s lung or belly. Furosemide helps remove this excess fluid from their lungs or belly. As a result, your dog should be able to breathe better.
Furosemide can impact your dog’s kidneys because they’re working hard to remove excess fluid. There is some evidence that suggests dogs can develop a kidney injury while taking furosemide. But most of the kidney injuries weren’t serious — and they weren’t kidney failure.
Your veterinarian will likely want to monitor your dog’s kidney values and electrolytes while they’re on furosemide. This will help ensure your dog (and their kidneys) are handling the medication well.
Yes, dogs can take human furosemide. The tablets are the same for people as they are for dogs. That means you can fill your dog’s prescription right at your regular pharmacy.
But never give your dog furosemide without first talking to your veterinarian. Your dog will take a different dosage of the medication than a human. Without a vet’s guidance, your dog may experience a dangerous overdose.
The bottom line
Furosemide (Lasix, Salix) is a diuretic that’s used in veterinary medicine to treat a variety of medical conditions in dogs. But it’s most often used to treat congestive heart failure in dogs.
Treating a dog with furosemide is a balancing act. The best dosage removes enough fluid to manage their symptoms but not enough fluid to cause dehydration. Work with your veterinarian to keep an eye on your dog’s health, and be prepared to make changes if needed.
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References
Brooks, W. (2021). Furosemide (Lasix, Salix, Disal). Veterinary Partner.
Dowling, P. M. (2023). Diuretics used to treat urinary disease in animals. Merck Veterinary Manual.
Giorgi, M. E., et al. (2022). Retrospective evaluation of risk factors for development of kidney injury after parenteral furosemide treatment of left-sided congestive heart failure in dogs. Journal of Veterinary Internal Medicine.
Gordon, S. G., et al. (2023). Diuretics for use in animals. Merck Veterinary Manual.
Ham, K. (2023). Hypercalcemia in dogs and cats. Merck Veterinary Manual.
Merck Animal Health. (n.d.). Salix (furosemide injection).
Oishi, N., et al. (2012). Ototoxicity in dogs and cats. Veterinary Clinics of North America: Small Animal Practice.
Rishniw, M. (2024). Congestive heart failure in dogs and cats. Veterinary Partner.
