CHICAGO — Veterinarians across the country are reporting an uptick in mold-related illness in companion animals following the record flooding events of early 2026, warning pet owners that the same toxic mold species threatening human health can cause severe respiratory and neurological illness in dogs and cats.
Stachybotrys chartarum, commonly known as black mold, produces mycotoxins that are particularly dangerous to small animals due to their lower body weight and tendency to spend more time at floor level — where mold spore concentrations are typically highest in a water-damaged structure.
Dr. Lena Forsythe, a veterinary internal medicine specialist at the University of Illinois College of Veterinary Medicine, said the most common presenting symptoms in mold-exposed pets include persistent coughing, nasal discharge, lethargy, loss of appetite, and in severe cases, seizure activity consistent with mycotoxin-induced neurological damage.
"We see a lag of two to six weeks between initial mold exposure and the onset of clinical symptoms," Dr. Forsythe said in a February 2026 continuing education webinar hosted by the American Veterinary Medical Association. "By the time owners bring the animal in, the exposure has often been ongoing for a month or more."
Veterinarians recommend that pet owners whose homes have sustained water damage relocate animals to unaffected areas during remediation and consult a veterinarian immediately if respiratory or behavioral changes are observed. Blood panels testing for inflammatory markers and liver enzyme elevation can help confirm mycotoxin exposure.
