Furosemide
Salix, Lasix (veterinary and human) · generic furosemide
Furosemide is a diuretic that keeps fluid out of the lungs in dogs and cats with heart failure, and it is used for other fluid build-up. Veterinary versions are approved, and the human generic is the same drug.
What it is used for
Furosemide makes the kidneys remove salt and water quickly. In heart failure it is the drug that relieves the breathing difficulty caused by fluid in the lungs, and the dose is adjusted up and down by the vet against the animal’s breathing rate, which owners are taught to count at home while the pet sleeps. It is used with pimobendan and an ACE inhibitor in dogs, and in cats with heart disease.
Salix is a veterinary brand; the human tablets are the same drug. Increased thirst and urination are expected. Dehydration and low potassium are the risks, so blood tests are checked after dose changes, and torsemide is sometimes used when furosemide stops working well.
Giving it to your pet
- How to give it
- As prescribed, often once to three times a day. Your pet will urinate more, so always leave fresh water out and allow more chances to go outside or use the litter box; never restrict water.
- If you miss a dose
- Give it as soon as you remember, unless it is nearly time for the next dose; in that case skip the missed dose and carry on as usual. Never give two doses at once to catch up. Avoid giving a late dose at bedtime unless your vet advises it.
- Storage
- At room temperature, protected from light.
- Call your vet if you see
- For heart failure, count your pet’s breathing rate while it sleeps and call your vet if it rises above the limit your vet gave you, or for coughing or breathlessness. Also call for weakness, collapse, dry gums or loss of appetite, which can signal dehydration.
Your vet’s instructions and the label on your pet’s medicine take priority over this general information.
Safety points that differ from human use
- A pet on furosemide must always have water available; restricting water to reduce urination is dangerous.
- Vomiting, diarrhea or refusing to drink can cause rapid dehydration on this drug; call the vet.
- Breathing faster than the rate the vet sets while resting, or at night, is an emergency sign that the dose is not enough.
- Tablets (human and veterinary)
- Oral solution (human)
- Injection (clinic use)
- Compounded liquids for cats
- 20, 40 and 80 mg human tablets
- 12.5 and 50 mg veterinary tablets
Why the cash price varies
Each pharmacy sets its own cash price, so quotes for the same furosemide prescription can differ. The veterinary tablets come in a small strength useful for cats and the human tablets in larger strengths, so the product on the prescription shapes what is quoted. Doses change often in heart failure, so new prescriptions and more than one strength are common.
Upload it and licensed pharmacies reply with their own cash price. You pay the pharmacy, not us.
How to pay less
- Ask the vet whether the human generic is suitable and which strength keeps the tablet count simple.
- Ask the vet whether a ninety-day prescription is appropriate once the dose is stable.
- If a different strength would be easier to fill, the pharmacist may contact your vet; only the vet can change the prescription.
- Upload the prescription to Script Unlock so licensed pharmacies can quote. You pay the pharmacy directly.
Questions for your vet
- What resting breathing rate should I count, and what rate means I should call?
- What should I do if my pet vomits or will not drink?
- When are the kidney and potassium checks?
- How is the dose adjusted, and can I adjust it myself under instruction?
- Can I use the human generic tablet?
The same medicine is prescribed for people: see the Furosemide guide for how it is supplied and priced at pharmacies.
Rules on refills, transfers and controlled substances differ by state; see pharmacy rules by state.
How Script Unlock gets you a cash price for your pet’s furosemide prescription
Prices on this site come from pharmacies responding to a real prescription. We do not publish estimated, average or "typical" prices, because none of those would be your price.
- 1You upload your prescription
A photo of your your pet’s furosemide prescription prescription is enough. Nothing is sold on the site; you are asking pharmacies to quote.
- 2Licensed pharmacies respond
Pharmacies that Script Unlock has verified see the request and each can reply with its own cash price for your exact drug, strength and quantity.
- 3You choose and pay the pharmacy
You compare the responses, pick a pharmacy, and pay that pharmacy directly when you collect. Script Unlock never takes a patient payment and never sets the price.
Related pet medications
Sources
- FDA Approved Animal Drug Products (Green Book)
- Merck Veterinary Manual
- FDA Orange Book (approved generics and therapeutic equivalence)
- MedlinePlus drug information (National Library of Medicine)
Written by the Script Unlock editorial team from the sources above. Not yet reviewed by a veterinarian or veterinary pharmacist. Last checked 2026-10-03. Nothing here replaces your vet’s directions; doses for animals are set by weight and species.
Script Unlock is a marketplace that lets licensed pharmacies quote a cash price on your prescription. It does not prescribe, dispense or sell medication, does not process patient payments, and does not give medical advice. Always follow the instructions of your prescriber and pharmacist and read the medication guide supplied with your medicine.