A covered box has a hood and often a flap, hiding odour and scattered litter and looking tidier. An open box has no cover, ventilates well, has no threshold, and lets you see the base and clumps at a glance when cleaning.

Covered boxes suit living rooms where odour and scatter matter, but concentration inside is higher and cleaning must be more frequent. Open boxes suit well-ventilated spots and are easier for seniors, post-surgery cats and larger cats.

The trade-off is odour versus comfort: a hood traps smell, which burdens the cat's nose, and some cats refuse it. Open boxes scatter more, raising floor-cleaning frequency. With flap models, confirm the cat will push through.

Decide by the cat's size, age and where the box sits, and provide one per cat plus one in multi-cat homes. If a cat urinates outside the box or squats for long without producing urine, seek veterinary care promptly.