What is furosemide?
Furosemide (brand names: Lasix®, Salix®, Disal®) is a diuretic used to treat conditions such as congestive heart failure, lung fluid retention, and certain kidney diseases.
It can also be used to aid in the treatment of high blood potassium and high blood pressure. In racehorses, it has been used to prevent exercise-induced lung bleeding.
Its use in cats and dogs at labeled doses is FDA approved; however, its use at other doses or use in ferrets and other small mammals, horses, birds, and reptiles to treat various conditions is “off label” or “extra label”. Many drugs are commonly prescribed for off-label use in veterinary medicine. In these instances, follow your veterinarian’s directions and cautions carefully, as they may be significantly different from those on the label.
How is furosemide given?
Furosemide is given by mouth, in the form of a tablet or liquid. It can also be given by injection in the hospital or clinic.- It may be given with or without food; however, if vomiting occurs when dosed on an empty stomach, give future doses with food or a treat.
- Measure liquid doses carefully.
- Ensure your pet always has access to plenty of fresh, clean water while on this medication.
- Avoid dosing close to bedtime, as this medication causes frequent urination.
- If you are allergic to sulfa medications, you should wear gloves when handling this medication.
This medication will take effect quickly, in about 1 to 2 hours, and improvement in clinical signs should follow.
What if I miss giving my pet the medication?
If you miss a dose, give it as soon as you remember, and then continue with the regular dosing schedule. However, if it is almost time for the next dose, skip the missed dose and resume the regular dosing schedule. Do not give the pet two doses at once.
Are there any potential side effects?
Furosemide may cause the following side effects:
- increased urination (most common)
- diarrhea
- constipation
Serious adverse reactions may occur. If any of the following signs develop, stop giving furosemide and contact your veterinarian immediately:
- weakness
- collapse
- head tilt
- balance problems
- electrolyte imbalance
- lack of urine production
- racing heart rate
This short-acting medication should stop working within 24 hours, although effects can be longer in pets with liver or kidney disease.
Are there any risk factors for this medication?
Furosemide should NOT BE USED in pets that:
- are allergic to it
- are unable to make urine
- have worsening kidney disease
Furosemide should be USED WITH CAUTION in pets that:
- are dehydrated
- have an electrolyte imbalance
- have liver or kidney disease
- have diabetes mellitus
- are actively vomiting or having diarrhea
- are pregnant or lactating
- are allergic to sulfonamides (as they may also be sensitive to furosemide)
Are there any drug interactions I should be aware of?
Be sure to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your pet is taking. The following medications should be used with caution when given with furosemide:
- angiotensin-converting enzyme (ACE) inhibitors
- aspirin
- corticosteroids
- digoxin
- insulin
- theophylline
Furosemide may increase other drugs’ potential to damage the kidneys (nephrotoxic) or cause hearing loss (ototoxicity).
Furosemide can also cause a falsely elevated Free T4 lab value.
Is any monitoring needed with this medication?
Your veterinarian will monitor for:
- electrolyte levels
- kidney values
- blood sugar levels
- hydration
If indicated, the following measures will also be monitored:
- blood pressure
- weight
- ear function
Your veterinarian may monitor your pet to be sure that the medication is working.
How do I store furosemide?
- Store at room temperature.
- Protect from light and freezing.
What should I do in case of emergency?
If you suspect an overdose or an adverse reaction to the medication, call your veterinary office immediately. If they are not available, follow their directions in contacting an emergency facility.
