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PetDosageChart

Lasix (Furosemide) Dosage for Dogs

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

This dosage information is for educational purposes only. Always consult your veterinarian before giving any medication to your pet. Dosages may vary based on your pet's health conditions, other medications, and individual factors.

Content reviewed by licensed veterinarians. This information is sourced from veterinary drug references including Plumb's Veterinary Drug Handbook and the Merck Veterinary Manual.

Dosage Calculator

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Lasix Dosage Chart for Dogs by Weight

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Weight Low Dose Standard Dose Max Dose Frequency
5 lbs (2.3 kg) 2.5mg 4.5mg 9mg Every 8-12 hours
10 lbs (4.5 kg) 4.5mg 9mg 18mg Every 8-12 hours
15 lbs (6.8 kg) 7mg 13.5mg (12.5mg tablet) 27mg (2 × 12.5mg) Every 8-12 hours
20 lbs (9.1 kg) 9mg 18mg 36.5mg (3 × 12.5mg) Every 8-12 hours
25 lbs (11.3 kg) 11.5mg (12.5mg tablet) 22.5mg (2 × 12.5mg) 45mg Every 8-12 hours
30 lbs (13.6 kg) 13.5mg (12.5mg tablet) 27mg (2 × 12.5mg) 54.5mg Every 8-12 hours
40 lbs (18.1 kg) 18mg 36mg (3 × 12.5mg) 72.5mg (6 × 12.5mg) Every 8-12 hours
50 lbs (22.7 kg) 22.5mg (2 × 12.5mg) 45.5mg 91mg Every 8-12 hours
60 lbs (27.2 kg) 27mg (2 × 12.5mg) 54.5mg 109mg Every 8-12 hours
70 lbs (31.7 kg) 31.5mg 63.5mg (5 × 12.5mg) 127mg (10 × 12.5mg) Every 8-12 hours
80 lbs (36.3 kg) 36.5mg (3 × 12.5mg) 72.5mg (6 × 12.5mg) 145mg Every 8-12 hours
90 lbs (40.8 kg) 41mg 81.5mg 163mg (13 × 12.5mg) Every 8-12 hours
100 lbs (45.4 kg) 45.5mg 91mg 181.5mg Every 8-12 hours
120 lbs (54.4 kg) 54.5mg 109mg 217.5mg Every 8-12 hours
150 lbs (68 kg) 68mg 136mg (11 × 12.5mg) 272mg (22 × 12.5mg) Every 8-12 hours

What is Lasix (Furosemide) used for in dogs?

Congestive heart failure Pulmonary edema Pleural effusion Ascites Acute fluid overload

How to give Lasix 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.

Available Forms

Tablet, Oral liquid, Injectable

Give with Food?

Yes — give with food

Side effects of Lasix in dogs

Common side effects

Increased urination (expected effect)
Increased thirst
Electrolyte imbalance (low potassium, sodium)
Dehydration

Serious side effects

  • Severe dehydration and prerenal azotemia
  • Hypokalemia (dangerously low potassium)
  • Ototoxicity (hearing loss, especially with rapid IV use)
  • Metabolic alkalosis
  • Acute kidney injury

When to call the vet

Call your vet immediately if your dog shows any of these signs:

  • 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)

Related Medications for Dogs

Inodilator (positive inotrope and vasodilator)

Vetmedin

Pimobendan

For Congestive heart failure

View dosage chart
ACE inhibitor (angiotensin-converting enzyme inhibitor)

Vasotec

Enalapril

For Congestive heart failure

View dosage chart
Antihistamine

Benadryl

Diphenhydramine

For allergies

View dosage chart
Serotonin antagonist and reuptake inhibitor (SARI)

Desyrel

Trazodone

For anxiety

View dosage chart

Sources & References

The dosage information on this page is compiled from the following veterinary and pharmaceutical references:

  • Plumb's Veterinary Drug Handbook — the standard veterinary pharmacology reference used by veterinarians worldwide.
  • Merck Veterinary Manual — a trusted, peer-reviewed resource for veterinary professionals and pet owners.
  • DailyMed (FDA Drug Labels) — official FDA-approved drug labeling and prescribing information for Furosemide.

Frequently Asked Questions

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.

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