Furosemide for Pets
Furosemide is a prescription diuretic commonly used in dogs and cats to help remove excess fluid from the body. It is most often prescribed for heart-related fluid buildup, but veterinarians may also use it for some kidney-related conditions and other specific medical needs.
Quick Facts About Furosemide
Drug class
Loop diuretic
Common brand names
Lasix®, Salix®, Disal®
Forms
Tablet, oral liquid, and injection
Species
Used in dogs and cats
What Furosemide Is Used For
Furosemide is a loop diuretic, sometimes called a “water pill.” It helps the kidneys remove more salt and water into the urine, which reduces excess fluid in the lungs, chest, abdomen, or other tissues. In veterinary medicine, it is most commonly used to treat congestive heart failure and fluid retention such as pulmonary edema or pleural effusion. Veterinarians may also prescribe it in some cases involving certain kidney diseases, high blood potassium, or high blood pressure. Cats are generally more sensitive to furosemide than dogs, so monitoring is especially important.
Side Effects to Watch For
Many pets tolerate furosemide well, but side effects can happen, especially if the pet becomes dehydrated or develops electrolyte imbalances.
- Common side effects: increased urination, increased thirst, and needing to go outside or to the litter box more often
- Digestive side effects: vomiting, diarrhea, constipation, or reduced appetite
- Signs of dehydration or electrolyte problems: weakness, lethargy, dry gums, wobbliness, or acting unusually tired
- More serious concerns: collapse, racing heart rate, trouble producing urine, head tilt, or balance problems
- Rare but important risk: hearing-related toxicity has been reported, especially with high injectable doses or when combined with other drugs that may affect hearing
Dosing & Administration
Always follow your vet's instructions exactly. Furosemide may be given by mouth as a tablet or liquid, or by injection in a hospital setting. It can often be given with or without food, but if your pet vomits on an empty stomach, ask your veterinarian whether giving it with food is appropriate. Because this medication increases urination, many pets need more frequent bathroom breaks. Make sure your pet has access to fresh water unless your veterinarian has told you otherwise. Measure liquid doses carefully, and do not change the dose, stop the medication, or double up after a missed dose unless your veterinarian tells you to. If you miss a dose, contact your vet for guidance; if it is close to the next scheduled dose, your vet may advise skipping the missed dose rather than giving two doses together.
When to Call a Vet
Go to the ER now
- ● Your pet is having trouble breathing, collapses, or becomes suddenly very weak
- ● Signs of an allergic reaction such as facial swelling, hives, or severe breathing difficulty
- ● Possible overdose or accidental ingestion of extra medication
- ● No urine production, severe dehydration, or extreme lethargy
- ● Severe wobbliness, head tilt, or sudden balance problems
See a vet within 24 hours
- ● Vomiting, diarrhea, or poor appetite that does not improve
- ● Drinking or urinating much more than expected
- ● Weakness, restlessness, or a racing heartbeat
- ● Your pet has kidney disease, diabetes, or is on other medications and seems unwell
- ● You are unsure whether to give the next dose after a missed dose or side effect
Watch at home, call if it worsens
- ● Mild increase in thirst or urination
- ● Needing more bathroom or litter box access
- ● Mild stomach upset that resolves quickly
- ● Temporary changes in routine after starting the medication
Common Questions About Furosemide
Can I give my dog human furosemide?
What happens if I miss a dose?
Can my cat take furosemide?
What should I do if my pet is drinking and urinating more?
Are there medications that interact with furosemide?
Disclaimer: The information provided in this article is for educational purposes only and does not constitute veterinary medical advice. Reading this content does not establish a veterinarian-client-patient relationship. Every pet is different — always consult a licensed veterinarian before making decisions about your pet's health, diet, or care. If you'd like personalized guidance, you can talk to one of our vets. If your pet is experiencing a medical emergency, contact your local emergency animal hospital immediately.