Dermatologic Adverse Effect of Subcutaneous Furosemide Administration in a Cat

In a case report, a 2-year-old domestic shorthair cat with congestive heart failure (CHF) developed dermatologic adverse effects, including well-defined circular, crusted ulcerative cutaneous lesions and alopecia, following subcutaneous furosemide (SF) administration. This reaction occurred after the cat's treatment was switched from oral to subcutaneous furosemide to manage recurrent lung edema. The skin issues arose 2 weeks after starting SF and were resolved within 1 month after switching to an alternative brand of furosemide, while maintaining the same dose and administration route. This case is the first to document such a dermatologic side effect of SF in feline medicine, suggesting that, similar to dogs and humans, cats may also experience skin reactions to SF.