Why mold turns ivy into a double threat
Your Persian's vomiting suggests the ivy's natural toxins weren't the only problem—those damp leaves likely hosted mold that multiplied overnight. Mold breaks down plant cell walls, effectively concentrating the ivy's irritating saponins while adding its own inflammatory compounds. At 4 kg, your cat has little body mass to dilute these combined irritants.
Watch for a pattern in the vomiting: mold-related upset often causes more frequent episodes than plant toxicity alone. The vomit may contain leaf fragments or have a sour, fermented smell. Pawing at the mouth is especially common with moldy ivy because fungal compounds can cause a burning sensation on delicate feline tongues.
The Persian factor in plant poisoning
Brachycephalic breeds like Persians often react more severely to oral irritants due to their compact anatomy. Their shallow gag reflexes make vomiting more violent, and their small airways are easily compromised by excessive drooling. Your cat's flat face means even mild mouth irritation from the ivy could cause noticeable discomfort.
At 4 kg, she's firmly in the high-risk weight category for toxic plant ingestion. What might cause temporary drooling in a larger cat can lead to pronounced vomiting in her. The mold adds another layer—fungal toxins affect cats more powerfully than dogs due to differences in liver metabolism. Monitor her especially closely for tremors or unusual lethargy.
Overnight degradation changes the game
Fresh English ivy contains primarily hederasaponins, which irritate mucous membranes. But after hours in water, bacterial action starts breaking these down into simpler, more rapidly absorbed compounds. The vase water itself may have concentrated these irritants—if your cat drank from it too, she got a double dose of trouble.
Mold growth follows a predictable timeline in damp conditions. By the 12-hour mark (common with overnight exposures), colonies are mature enough to produce noticeable quantities of mycotoxins. These interfere with nerve function in ways that pure plant toxins don't, potentially causing wobbliness or dilated pupils alongside the vomiting you're seeing.
Emergency signs in petite felines
For a 4 kg cat, the margin between mild irritation and serious poisoning is slim. Any vomiting more than twice in an hour, or inability to keep water down, requires immediate vet attention. Watch her breathing—Persians are prone to stress-induced respiratory distress, and excessive drooling can further obstruct those already cramped airways.
Mold toxicity often announces itself through neurological signs. If your cat seems uncoordinated, presses her head against surfaces, or has unusually large pupils, don't wait for more vomiting. These suggest the fungal compounds have moved beyond local gut irritation to systemic effects. Time matters now; collect a sample of the ivy and any vomit containing plant material for your vet.
The step-by-step response, from the first minute to the vet visit, is in our English Ivy Toxicity in Dogs and Cats emergency guide.