Vitamin C: the guinea pig's built-in dietary trap
Unlike most pets, guinea pigs cannot manufacture vitamin C in their bodies, so every bit must come from food, every day. When intake falls short, the signs creep in over weeks: a rough, thinning coat, sore joints and a guinea pig that moves stiffly or cries when picked up, wounds that heal slowly, loose teeth, and a general loss of condition. Owners often blame age or boredom, when the fix begins with diet.
Prevention is a daily routine rather than a supplement hunt: good quality guinea pig pellets, unlimited grass hay, and a daily portion of vitamin C-rich vegetables such as bell pepper or leafy greens. If your guinea pig shows the stiffness, coat change, and appetite dip pattern, book a vet — scurvy-level deficiency needs professional assessment, and the same signs can overlap with other problems a vet should rule out.
Teeth and the gut that must not stop
Guinea pig teeth grow throughout life, and molar overgrowth is a leading cause of the guinea pig that approaches food eagerly, then eats little. Clues include drooling with a wet chin, choosing soft vegetables over hay, dropping food, smaller droppings, and weight loss you can feel along the spine. Front teeth can look perfectly normal while the back teeth cause the pain, so do not let tidy incisors reassure you.
A guinea pig's digestion also depends on near-constant eating. A pig that stops eating for most of a day, whose droppings shrink or stop, is an urgent case — gut slowdown follows quickly and compounds whatever started it. Same-day vet contact is the standard for a guinea pig off its food.
Breathing: the emergency that escalates fastest
Respiratory infections are the problems guinea pigs hide until they are serious. Watch for sneezing that becomes frequent, discharge crusted around the nostrils, clicking or raspy breathing, breathing with visible effort, and the classic puffed-up, hunched, quiet posture in a corner. A guinea pig breathing with its mouth open or sides heaving needs a vet immediately, not in the morning.
Keep the hutch or cage away from draughts, use low-dust bedding, and separate a clearly unwell pig from companions while you arrange the visit, since these infections pass between cage-mates.
Bladders, feet, skin, and sows
Squeaking while urinating, straining, or pink or red urine can point to bladder sludge or stones, which guinea pigs develop readily — any blood in urine earns a prompt vet visit. Check feet weekly: wire or mesh floors and soiled bedding cause swollen, infected footpads, and a limping pig or one reluctant to move may be telling you about its feet, not its joints. Itchy scratching with flaky skin or hair loss can mean mites or fungal infection, both contagious between pigs. In unspayed older females, gradual hair loss on both flanks alongside a swelling belly is a pattern vets associate with ovarian cysts and should be examined.
Weigh every guinea pig weekly — weight is the earliest honest signal this species gives. Record weights, appetite changes, and vet findings in each pig's KinsLe Pet Passport, so a slow slide is visible in numbers long before it is obvious in the cage.