How a 3 kg cat's size turns this into a race
Your British Shorthair's compact body means the battery has less distance to travel before reaching dangerous narrow points in the digestive tract. At this weight, even a small button cell can completely block the esophagus or puncture the stomach wall as the electrical burns weaken tissues.
The party environment likely delayed your notice—with noise and movement distracting everyone, she may have chewed it longer than usual before swallowing. Batteries from gifts often have residual flavorings that attract cats, making them less likely to spit it out immediately.
The two-stage danger of swallowed pieces
If she didn't swallow it whole, the jagged edges of a chewed battery present additional risks beyond the electrical current. Sharp metal fragments can lacerate the mouth and throat on the way down, while the exposed inner materials leak faster than an intact battery would.
Unlike larger pets where a battery might pass uneventfully, a 3 kg cat's intestines are too narrow to safely handle even small debris. The combination of mechanical injury and chemical burns creates a perfect storm for perforation within hours.
Why symptoms lie in the first hour
You might see her grooming normally or even eating treats afterward, but this false reassurance is treacherous. The initial pain from mouth injuries often subsides briefly as nerve endings are damaged, only to return worse when deeper layers are affected.
Watch for subtle behavior changes like sitting with her neck extended oddly or avoiding her favorite high perches. These suggest throat pain is developing. Any vomiting attempts—even dry heaving—require immediate update to your vet.
The critical hospital supplies to mention
When you call the clinic en route, specify it's a button battery from a child's toy—these often contain higher lithium concentrations than watch batteries. This changes how aggressively they'll treat potential systemic absorption.
Ask if they have pH-neutralizing oral gels available; some emergency clinics stock these specifically for battery cases. Don't be alarmed if they prepare oxygen support—swelling from the burns can sometimes compromise airways in small cats.
The step-by-step response, from the first minute to the vet visit, is in our Batteries (Alkaline, Lithium, Button) emergency guide.