Cats living in water-damaged homes are six times more likely to develop aspergillosis — a serious and potentially fatal fungal infection caused by Aspergillus mold species — compared to cats in unaffected homes, according to a veterinary study published in the Journal of Feline Medicine and Surgery in January 2026.
The study tracked 400 households, 200 with documented water damage and 200 without, over a two-year period. Of the 200 cats in water-damaged homes, 34 developed confirmed aspergillosis, compared to six cats in the control group.
Aspergillosis in cats typically presents as chronic nasal discharge, sneezing, facial swelling, and in disseminated cases, neurological signs and organ failure. The condition is frequently misdiagnosed as a bacterial infection and treated with antibiotics, which are ineffective against fungal disease.
The study authors recommend that veterinarians include aspergillosis in the differential diagnosis for any cat presenting with chronic upper respiratory symptoms, particularly when the owner reports water damage or musty odors in the home.
Treatment with antifungal medications is effective in early-stage cases but requires prolonged therapy and carries significant cost. Prevention through prompt professional remediation of water-damaged homes remains the most effective strategy.
