Loop diuretic · For Dogs

Lasix dosage reference for dogs (Furosemide)

This page's standard weight-based reference is 2 mg per kg (0.91 mg per lb), with Every 8-12 hours recorded as the reference frequency. Use the calculator to see the arithmetic for your dog's weight, then confirm the indication, product, and actual dose with a veterinarian.

Onset: 30-60 minutes (oral); 5 minutes (IV)
Duration: 6-8 hours
Class: Loop diuretic

Weight-based calculator estimate from the references listed on this page. This page has not been independently DVM-reviewed — see our methodology .

This information is for educational purposes only. Always consult your veterinarian before giving medication to your pet. Do not use this calculator for emergencies, overdoses, pregnancy, very young animals, very old animals, pets with liver/kidney disease, or pets taking multiple medications.

Each medication page lists the references recorded for its data. The calculator math and editorial presentation are maintained by PetDosageChart; a page is independently DVM-reviewed only when a named reviewer byline appears. See our methodology and limitations.

Furosemide (often known by brand names such as Lasix and Salix) is a loop diuretic commonly used in veterinary medicine for Congestive heart failure, Pulmonary edema, Pleural effusion, Ascites, and Acute fluid overload. Understanding the correct dosage, administration, and potential side effects of Furosemide is critical for your dog’s safety and well-being.

A typical Furosemide dose for dogs is around 2 mg/kg Every 8-12 hours, within a usual range of 1-4 mg/kg. Available forms include Tablet, Oral liquid, and Injectable.

Calculator Warning: Use this only as an educational estimate. Your veterinarian may prescribe a different dose based on your pet’s condition, age, weight, other medications, and medical history.

Furosemide Dosage Calculator for Dogs

Enter your dog’s weight below to estimate the Furosemide dose from the 2 mg/kg guideline. Your veterinarian may adjust it for your dog’s age, condition, and other medications, so treat the result as an educational starting point, not a prescription.

Dosage Calculator · 01

Enter your dog's weight

Quick Dosage Chart

Typical Furosemide amounts for common dog weights, for quick reference:

Dosage Chart · 02

Lasix weight-based reference chart for dogs

Scroll sideways to see full table

Weight	Lower Reference	Standard Reference	Upper Reference	Frequency
5 lbs (2.3 kg)	2.3 mg	4.6 mg	9.2 mg	Every 8-12 hours
10 lbs (4.5 kg)	4.5 mg	9.0 mg	18.0 mg	Every 8-12 hours
15 lbs (6.8 kg)	6.8 mg	13.6 mg (12.5mg tablet)	27.2 mg (2 × 12.5mg)	Every 8-12 hours
20 lbs (9.1 kg)	9.1 mg	18.2 mg	36.4 mg (3 × 12.5mg)	Every 8-12 hours
25 lbs (11.3 kg)	11.3 mg (12.5mg tablet)	22.6 mg (2 × 12.5mg)	45.2 mg	Every 8-12 hours
30 lbs (13.6 kg)	13.6 mg (12.5mg tablet)	27.2 mg (2 × 12.5mg)	54.4 mg	Every 8-12 hours
40 lbs (18.1 kg)	18.1 mg	36.2 mg (3 × 12.5mg)	72.4 mg (6 × 12.5mg)	Every 8-12 hours
50 lbs (22.7 kg)	22.7 mg (2 × 12.5mg)	45.4 mg	90.8 mg	Every 8-12 hours
60 lbs (27.2 kg)	27.2 mg (2 × 12.5mg)	54.4 mg	108.8 mg	Every 8-12 hours
70 lbs (31.7 kg)	31.7 mg	63.4 mg (5 × 12.5mg)	126.8 mg (10 × 12.5mg)	Every 8-12 hours
80 lbs (36.3 kg)	36.3 mg (3 × 12.5mg)	72.6 mg (6 × 12.5mg)	145.2 mg	Every 8-12 hours
90 lbs (40.8 kg)	40.8 mg	81.6 mg	163.2 mg (13 × 12.5mg)	Every 8-12 hours
100 lbs (45.4 kg)	45.4 mg	90.8 mg	181.6 mg	Every 8-12 hours
120 lbs (54.4 kg)	54.4 mg	108.8 mg	217.6 mg	Every 8-12 hours
150 lbs (68 kg)	68.0 mg	136.0 mg (11 × 12.5mg)	272.0 mg (22 × 12.5mg)	Every 8-12 hours

Parenthetical tablet amounts are arithmetic comparisons only. They do not account for scoring, release type, concentration, product labeling, or whether this medication is appropriate for an individual animal.

By Weight

Lasix reference by dog weight

Choose a common weight to open its optional reference page. Use the main medication calculator for a different exact weight.

Common-weight pages are convenience views of the same educational reference, not separate medical recommendations.

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How to Give Furosemide to Your Dog

Give furosemide tablets by mouth with food if it causes stomach upset. Ensure unlimited access to fresh water at all times. Administer at consistent times each day. Plan the last dose early enough in the evening to allow the dog to urinate before bedtime. More frequent outdoor access will be needed. Monitor your dog’s resting respiratory rate daily.

It is generally recommended to give Furosemide with food to help reduce stomach upset. It may interact with ACE inhibitors — first-dose hypotension; start at low doses, Aminoglycoside antibiotics — increased risk of ototoxicity and nephrotoxicity, Digoxin — hypokalemia increases digoxin toxicity risk, NSAIDs — may reduce diuretic effectiveness, and Corticosteroids — additive potassium loss.

Side Effects and Safety

Common side effects include Increased urination (expected effect), Increased thirst, Electrolyte imbalance (low potassium, sodium), and Dehydration. More serious side effects can occur, such as Severe dehydration and prerenal azotemia, Hypokalemia (dangerously low potassium), Ototoxicity (hearing loss, especially with rapid IV use), Metabolic alkalosis, and Acute kidney injury.

Cautions · 12

When Lasix should be used with caution or avoided

Some dogs should not take Lasix, or need a different dose and closer monitoring. Tell your veterinarian about your pet's full health history and every other medication or supplement they take before giving Lasix.

Anuria (no urine production)
Severe dehydration or hypovolemia
Severe electrolyte depletion
Known hypersensitivity to furosemide or sulfonamides

Interactions · 13

Lasix drug interactions

Lasix can interact with other drugs. This list is not complete — always give your veterinarian a full list of your dog's medications and supplements.

ACE inhibitors — first-dose hypotension; start at low doses

Aminoglycoside antibiotics — increased risk of ototoxicity and nephrotoxicity

Digoxin — hypokalemia increases digoxin toxicity risk

NSAIDs — may reduce diuretic effectiveness

Corticosteroids — additive potassium loss

Calculator Limits · 14

When not to use this calculator

This calculator gives a general educational estimate for a healthy adult dog at a known weight. Do not rely on it in these situations — talk to your veterinarian instead:

In an emergency, or after accidental ingestion or a suspected overdose
For pregnant or nursing pets
For very young or very old dogs
For pets with liver disease, kidney disease, or another chronic illness
For pets taking several medications at once
When you are not sure of your dog's current, accurate weight
For combination products that contain additional active ingredients

Overdose · 15

Suspected overdose: what to do

If you think your dog had too much Lasix, or swallowed any medication by accident, act right away. Do not wait for symptoms to appear.

Call your veterinarian or the nearest emergency animal hospital.
ASPCA Animal Poison Control Center: (888) 426-4435
Pet Poison Helpline: (855) 764-7661

A consultation fee may apply to the poison hotlines. Have the medication packaging ready, and note how much your pet may have taken and when. Do not try to make your pet vomit unless a veterinarian tells you to.

When to Call the Vet

If your dog experiences any of the following, contact your veterinarian or an emergency clinic immediately:

Resting respiratory rate above 40 breaths per minute despite medication
Severe lethargy, weakness, or collapse
Little or no urine production despite continued dosing
Persistent vomiting or loss of appetite
Muscle tremors or weakness (possible low potassium)

Frequently Asked Questions

Frequently Asked · 07

Questions about this medication

Why does my dog pee so much on furosemide?

Increased urination is the intended effect of furosemide. It works by blocking salt reabsorption in the kidneys, which pulls excess fluid from the body and eliminates it as urine. This is critical for removing dangerous fluid buildup around the lungs and heart in dogs with congestive heart failure. Ensure your dog always has access to fresh water.

Can furosemide cause kidney damage in dogs?

Excessive or prolonged furosemide use can lead to dehydration and prerenal kidney injury. Regular monitoring of kidney values (BUN, creatinine) and electrolytes is essential. Your vet will use the lowest effective dose and may adjust it based on your dog's response and lab results.

What electrolytes should be monitored in dogs on furosemide?

Potassium, sodium, and chloride should be monitored regularly. Furosemide causes significant potassium loss, which can lead to muscle weakness, heart rhythm disturbances, and other complications. Your vet may recommend potassium supplementation or a potassium-sparing diuretic like spironolactone.

Should I limit water for my dog on furosemide?

No, never restrict water for a dog on furosemide. The medication increases water loss through urination, and your dog needs free access to fresh water at all times to prevent dangerous dehydration. Increased thirst and drinking are expected and necessary.

Can furosemide be given with pimobendan and enalapril?

Yes, this triple combination is the standard of care for canine congestive heart failure. Furosemide removes excess fluid, pimobendan strengthens the heart, and enalapril reduces cardiac workload. When starting these together, your vet may introduce them sequentially and monitor for hypotension.

Use This Guide Safely · 08

What weight alone cannot tell you

The calculator performs one narrow job: it multiplies your dog's weight by the lower, standard, and upper mg/kg values recorded for Lasix. It cannot decide whether this drug, indication, formulation, or schedule is appropriate for an individual animal.

Context in this medication record

Commonly listed uses: Congestive heart failure, Pulmonary edema, Pleural effusion, Ascites, Acute fluid overload
Recorded forms: Tablet, Oral liquid, Injectable
Reference timing: Every 8-12 hours; onset 30-60 minutes (oral); 5 minutes (IV); duration 6-8 hours

Individual checks a calculator cannot perform

Confirm the diagnosis and the reason this medication is being considered.
Match the exact product, concentration, route, and whether a tablet may be split.
Account for age, pregnancy, organ function, genetics, allergies, and prior reactions.
Review every prescription, over-the-counter product, and supplement your pet takes.

Recorded cautions

Anuria (no urine production); Severe dehydration or hypovolemia; Severe electrolyte depletion; Known hypersensitivity to furosemide or sulfonamides.

Recorded interactions

ACE inhibitors — first-dose hypotension; start at low doses; Aminoglycoside antibiotics — increased risk of ototoxicity and nephrotoxicity; Digoxin — hypokalemia increases digoxin toxicity risk; NSAIDs — may reduce diuretic effectiveness; Corticosteroids — additive potassium loss.

These lists reproduce the structured record used by this page and may not be exhaustive. Show your veterinarian the product label and your dog's complete medication list before acting on a number.

Related · 08

Related medications for dogs

Sources · 09

Sources & references

The structured medication record behind this page names the references below. The links open the publisher or official resource; they do not turn this page into a prescription for an individual animal.

Plumb's Veterinary Drug Handbook — listed in this medication's source record.
Merck Veterinary Manual — listed in this medication's source record.
DailyMed label search for Furosemide — check current product and formulation labels; some veterinary uses may be off-label.

Source names are shown at the record level; passage-level page and label citations are still being added. Read our methodology and limitations.

Transparency · 11

How this page was made

This page's structured medication record includes Plumb's Veterinary Drug Handbook among its source names. PetDosageChart applies the record's mg/kg values to the entered weight and presents the arithmetic result. A source record is not the same as an individualized prescription or an independent clinical review.

Sources cited: Plumb's Veterinary Drug Handbook
Merck Veterinary Manual
Calculator formula: Doses scale linearly from a standard basis of 2 mg per kg (0.91 mg per lb) of body weight, given Every 8-12 hours. The calculator multiplies that basis by your dog's weight and shows an arithmetic comparison with recorded tablet sizes. That comparison does not determine whether a tablet is scored, splittable, or appropriate for your pet.
Editorial owner: Prepared and maintained by the PetDosageChart editorial team, a software-led publisher and not a veterinary practice.
DVM review status: Not independently DVM-reviewed. A named reviewer and review date appear here only after a confirmed review.

More on our methodology and editorial process — how we source, calculate, and review dogs dosage data.

Safety · 10

More resources

Pet Medication Safety Hub — What's safe, what's dangerous, and emergency signs
How we calculate dosages — Our sources, math, and review process
Printable emergency checklist — One-page reference for your fridge or first aid kit