Weigh monthly, on the same routine each time
An elderly Devon Rex should be weighed about once a month at home, using the same scales, on the same surface, and at roughly the same time of day, so the numbers can be compared fairly. Weigh her before a meal rather than straight after one, and write the result down immediately. A single reading matters less than the direction over two or three months, because a small, slender cat can lose a meaningful share of her body weight in an amount that sounds trivial.
The easiest method for an elderly Devon Rex who dislikes standing on scales is to weigh yourself holding her, then weigh yourself alone and subtract. Keep the carrier out of the routine if she associates it with car trips, because a tense, crouching cat shifts her weight and makes readings jump around. If she will stand on a flat kitchen scale for a treat, that stillness gives the cleanest number of all.
Check her over once a week, hands first
A brief weekly check suits an elderly Devon Rex because her fine, wavy coat and light build let changes develop quietly. Run your palms slowly over her ribs, spine, shoulder blades, and hips. You should feel ribs under a thin covering rather than sharp bone at every point, and the waist should taper gently rather than cave in. Compare left and right sides as you go, feeling for any new lump, sore patch, or area where she flinches or moves away.
Look at what her coat cannot hide. An elderly Devon Rex has delicate skin under that short coat, so check for flaking, redness, or scabs, especially along the back and at the base of the tail. Glance inside her large ears for heavy wax or debris, look at her eyes for new cloudiness or discharge, and lift a lip briefly to see whether her gums look pale or sore and whether a tooth looks broken or heavily coated. Check claws too, since a less active senior cat may not wear them down and a curled claw can press into a pad.
Note warmth, appetite, and litter habits alongside weight
An elderly Devon Rex feels the cold more than a thick-coated cat, and a new habit of pressing against radiators, burrowing under blankets all day, or shivering after a bath is worth noting beside her weight. Record how much of each meal she finishes, whether she asks for food then walks away, and any change in what the litter tray shows in amount or frequency. Those daily details turn a monthly number into a story a veterinarian can actually use.
Keep the check short and calm. Do it on a warm, non-slip surface where she already relaxes, pair it with stroking she enjoys, and stop to finish another day if she becomes restless. Forcing an elderly Devon Rex through a long examination teaches her to avoid the spot where it happens, which makes next week's check harder rather than more thorough.
When a home trend needs a vet sooner
Contact a veterinarian promptly if an elderly Devon Rex loses weight across two monthly readings, drops weight suddenly in a few weeks, stops eating for a day, or shows a new lump, sore mouth, or marked change in drinking or litter habits. Gradual, tiny fluctuation with steady appetite and behaviour can wait for a routine senior appointment, but a clear downward trend in a small elderly cat should never be watched for months at home. Bring the dated weights rather than a summary from memory.
Storing those monthly weights, weekly skin and ear notes, and appetite observations in KinsLe Pet Passport means her whole senior record sits in one portable packet at every check.