Appetite and body condition: the first honest signals
Old animals rarely announce decline with one dramatic change; they fade at the edges, and feeding is where it shows first. An elderly horse, goat, sheep or cow that once queued at the trough now arrives late, eats slowly, drops half-chewed feed, or walks away from a half-finished ration. Teeth wear is often part of it, and so is simple competition: younger, stronger animals shoulder the old one aside, and it gives up rather than argues. Run your hands over ribs, hips and spine regularly rather than judging by eye, because a winter coat or a goat's fleece hides a surprising amount of loss. Losing condition despite feed that is available, suitable and actually eaten is one of the clearest welfare warnings there is.
Rising, moving and keeping up
Watch the mechanics of an ordinary day. A very old animal that takes several attempts to rise, rocks to get its hind legs under it, or stays down long after the group has moved off is telling you its strength and joints are failing it. Lagging at the back on the walk to pasture, choosing not to make the trip at all, lying down in gateways and other awkward spots because getting up is an effort, and slipping or going down on wet or steep ground all belong in the same picture. Hooves and legs matter here too: the old animal that can no longer be safely caught, trimmed or treated without distress is losing more than mobility.
Interest in the world, and the herd
Healthy old animals stay themselves. They keep their place in the group, respond to feeding time, watch what is happening, and seek out the companions they have always preferred. The shift that owners remember afterwards is withdrawal: standing apart facing a fence, no interest in herd mates, no response to the bucket, a flat dullness where there used to be opinions. Pain often sits underneath that flatness, and farm animals hide pain well, so learn the quiet signs in your species: teeth grinding and a hunched, tucked stance in goats and sheep, a horse that stops rolling or stops lying flat out, a cow that separates herself and grinds through cud slowly or not at all. A single withdrawn day after bad weather means little; withdrawal as the new normal means a great deal.
The daily basics getting harder
Quality of life is measured in basics: can the animal eat enough, drink without a journey it dreads, reach shelter, stay clean and dry, and rest without being disturbed? The very old animal that cannot hold condition through a cold snap, that needs its rug or coat constantly adjusted, that gets cast in the stable or stuck in mud, or that needs rescuing from ordinary situations more and more often is an animal whose coping is running out. So is the one for whom routine care, foot trimming, injections, handling, has become a frightening ordeal rather than an annoyance.
Good days, bad days, and talking it through
The most useful tool an owner has is a simple record: a line a day noting appetite, mobility, interest and comfort, kept honestly over weeks. Trends settle arguments that single days cannot, because everyone remembers the worst afternoon and forgets the three decent days around it. When the bad days plainly outnumber the good, when several of the signs above arrive together, or when a hard winter is coming that the animal is unlikely to cope with, that is the point to open the conversation with your vet, in daylight and without an emergency forcing the pace. Keeping the daily notes in KinsLe's Pet Passport, alongside the animal's health history, gives that conversation a shared, factual footing, and gives you the comfort afterwards of knowing the decision was made on the animal's whole story.