At ten weeks, littermates are a useful comparison but a misleading ruler if you only look at size. One kitten may simply be the smaller build of the litter while hitting every functional milestone, and another may look sturdy yet be quietly behind in coordination or appetite. Compare what each kitten can do and how steadily she is progressing, not just who looks biggest in the nest or at the food bowl.
Weight and growth: trend over rank
Weigh each kitten at the same time of day, ideally before a meal, and compare the direction of travel across the litter. The kitten to watch is not automatically the lightest one, but the one whose line flattens or dips while her sisters keep climbing. Feel along the ribs and spine too: you should feel ribs under a light fat cover, not sharp bone or a pot belly that stays round even between meals. A ten-week kitten should look proportioned, with legs, head, and body growing together rather than a large belly on thin limbs.
Movement, senses, and coordination
By this stage a kitten should walk, trot, turn, and make clumsy but improving jumps, stalk a toy, miss, recover, and try again. Eyes should be clear and tracking movement on both sides, and she should react to sounds around her, even if she startles and then settles. Compare her with her littermates in the same play bout: occasional clumsiness is universal at ten weeks, but persistent wobbling, head tilt, dragging a leg, or repeatedly failing to land simple pounces stands out against siblings who manage them.
Eating, toileting, and daily habits
A ten-week kitten should be eating solid kitten food reliably, drinking water, and using the litter tray with only occasional accidents. Watch a full meal alongside her littermates: does she approach confidently, chew and swallow comfortably, and return for more, or does she lick, drop food, and drift away? Stools should be formed, urination regular, and grooming underway, though littermates will still wash each other. A kitten who is still trying to nurse to the exclusion of solid food at this age is behind her sisters in a way worth acting on. Add a gentle hands-on check to the same comparison. Teeth should be erupting cleanly without one side of the mouth looking sore or drooled on, ears should be clean and dry inside rather than waxy and scratchy, and her belly should feel soft after toileting rather than tight and uncomfortable. Run the check on a littermate straight afterwards and the contrast, if any, becomes obvious. A kitten who flinches at the same touch her sisters accept is giving you useful information to pass on, not a temperament verdict.
Social progress and when to book the vet
Healthy ten-week kittens play with littermates, solicit people, explore a room, and recover from small frights within minutes. Book a vet visit if your kitten gains no weight across several days, eats notably less than her littermates, seems lethargic between sleeps, has ongoing loose stool, sneezes persistently, or lags clearly in walking and play. Bring the comparison with you, because sibling context helps a vet judge a single kitten quickly. Keeping those weights and observations in her KinsLe Pet Passport means the vet sees her whole ten-week story in one packet, not a guess from memory.