Side Effects of Lasix in Older Dogs

Furosemide diuretic, better known as Lasix or Salix, is a primary treatment for congestive heart failure and the related pulmonary edema. It is available only by veterinary prescription. Congestive heart failure and pulmonary edema are most common in older dogs, and symptoms include constant coughing, fatigue and development of a pot belly. Lasix flushes excess fluid out of the lungs and other parts of the body. While it generally has few side effects, some older dogs may experience reactions. Don't give Lasix to any dog with a history of diabetes, kidney or liver disease, or with known allergies to sulfonamides.

  1. Electrolyte Imbalance and Dehydration

    • Dogs on Lasix, especially at high doses, need to have their blood potassium level and kidney function monitored every few months and should be observed for dehydration. Because Lasix is a diuretic, urination may increase substantially. Signs of electrolyte imbalance include constant thirst, restlessness, gastrointestinal disturbance and rapid heartbeat. Potassium loss may be alleviated with supplements.

    Gastrointestinal Side Effects

    • Vomiting, appetite loss, nausea and other gastrointestinal side effects have been reported in some dogs on Lasix. Call the veterinarian if the dog exhibits these symptoms, as they may also indicate electrolyte imbalance.

    Hearing Loss

    • When given in very high doses, Lasix has been known to cause hearing loss in dogs. Hearing loss is not uncommon in older dogs, but Lasix use is usually overlooked as a possible reason for increasing deafness. If an older dog who has been on Lasix starts ignoring voice commands, seems to ignore people or is no longer much of a watchdog, don't assume it's simply part of the aging process. While the hearing loss may be reversed to some degree when the dog is taken off the drug, consult a veterinarian to weigh the benefits and risks to the animal.