Why 10 mg is extreme for a 4 kg cat
Melatonin doses for cats are measured in fractions of a milligram—what your cat swallowed is hundreds of times that. Unlike dogs, cats lack efficient pathways to break it down, so even small amounts linger longer. This overdose will likely hit hard within an hour, with effects lasting up to 24 hours. The main risk isn't just sleepiness; it's the nervous system struggling to regulate basic functions like balance and breathing.
Watch for pupils that stay dilated in light, or a head that droops like your cat can't hold it up. Some cats vocalise distress from dizziness or nausea. If she's panting or her gums look paler than usual, skip monitoring and go straight to emergency care—oxygen support may be needed.
How this differs from a dog's reaction
Dogs might sleep off a melatonin overdose, but cats often show erratic responses—either collapsing or becoming strangely hyperactive. Your 4 kg body weight means even minor muscle tremors could escalate to full seizures. Unlike dogs, cats rarely vomit up pills, so you can't count on that reducing the dose.
Time matters here: if it's been under 30 minutes, the vet might use hospital-grade methods to prevent absorption. After two hours, the focus shifts to managing symptoms, which may require IV fluids to protect the kidneys from dehydration caused by lethargy.
Emergency signs that can't wait
Seizures look different in cats—not always dramatic convulsions. A cat 'freezing' with limbs stiff for over a minute, or repeatedly smacking her lips, counts. Any vocalisation during these episodes means pain or panic. Slow breathing (under 12 breaths per minute) or gaps longer than 10 seconds between breaths are critical.
Paradoxical agitation—hissing at walls, frantic running—is equally dangerous. It suggests neurological confusion that could lead to overheating or self-injury. Never try to 'calm' her with blankets or restraint; this increases stress. Dim lights and a carrier for transport are safer.
The first night after ingestion
Even if symptoms seem mild, set alarms to check her every two hours overnight. Cats can deteriorate rapidly as metabolism slows during sleep. Feel for body warmth—hypothermia is a risk with severe sedation. Offer water in a shallow dish, but don't force it; swallowing reflexes may be impaired.
By morning, if she's alert enough to groom or eat a teaspoon of wet food, the worst has passed. But any lingering clumsiness or disorientation means liver enzymes need checking—schedule a vet visit within 24 hours for bloodwork. Avoid all medications, even flea treatments, for the next three days.
The step-by-step response, from the first minute to the vet visit, is in our Sleep Aids (Melatonin, Zolpidem, Valerian) emergency guide.