Furosemide

What is this medication for?

• Pulmonary edema, CHF, hypercalcemia, hyperkalemia (adjunct), oliguric renal failure

How is it given?

Give exactly as your veterinarian prescribed — never change the dose or stop on your own unless your veterinarian has told you to.

• Goal is always the "lowest effective dose" — titrate to clinical signs (respiratory rate/effort), not a fixed target dose; give owners a dose range with instructions to adjust based on breathing vs. low energy/tiredness.
• Chronic use activates RAAS, which is why furosemide is almost always combined with an ACE inhibitor ± spironolactone in CHF management, not used alone long-term.

What if I miss a dose?

• Give it as soon as you remember — unless it is almost time for the next dose (then skip the missed one; never double up).
• Call your clinic if you miss more than one dose in a row.

Side effects — what should I watch for?

Effects listed as common in this handout

• Hyponatremia (more so than hypokalemia in dogs), dehydration (Common with chronic use)
• RAAS activation with repeated dosing → tolerance/attenuated effect (Documented (by day 5 at 2 mg/kg every 12 hours))

Worth a phone call to your veterinarian

• Ototoxicity (High-dose into a vein, especially cats)
• Pre-renal rising kidney values (If dehydration occurs)

⚠️ Contact your veterinarian or an emergency clinic IMMEDIATELY if you notice

• Trouble breathing, collapse, seizures, severe vomiting or diarrhea, facial swelling, or pale gums

Before starting (or refilling), tell your veterinarian if your pet:

• has or has had: Anuria; hypersensitivity
• has or has had: Pre-existing electrolyte/water imbalance, hepatic impairment (may precipitate hepatic coma), diabetes mellitus; possible sulfonamide cross-sensitivity

• is pregnant, nursing, or used for breeding
• is taking any other medications, supplements, or flea/tick products, including:
  • ACE inhibitors
  • Aminoglycosides, amphotericin B
  • Digoxin
  • NSAIDs
  • Corticosteroids

Storage and handling

Room temperature, protect from light. Do not mix with acidic solutions (pH <5.5 causes precipitation) — stable with alkaline drugs only.

Good to know

• Goal is always the "lowest effective dose" — titrate to clinical signs (respiratory rate/effort), not a fixed target dose; give owners a dose range with instructions to adjust based on breathing vs. low energy/tiredness.
• Cats are more sensitive to both the diuretic and ototoxic effects of furosemide than dogs.
• Chronic use activates RAAS, which is why furosemide is almost always combined with an ACE inhibitor ± spironolactone in CHF management, not used alone long-term.