The answer for a Campbell: pet food is the wrong food
A Khaki Campbell duck should not eat food made for other kinds of pets as anything more than a rare stolen peck, and it should never be offered deliberately. Dog and cat foods are formulated for mammals with single stomachs, different amino acid needs, and no egg production to support. A Campbell, by contrast, is a laying machine of a duck, and her feed has to deliver the niacin, calcium, and balanced protein that near-daily eggs demand. A bird filling up on pet food is a bird short-changing all three, even if she clearly enjoys the taste and crowds the dog's bowl to get it.
Niacin: the nutrient pet food does not give a duck
Niacin is the nutrient that most sharply separates duck feed from pet food. Ducks need substantially more niacin than chickens and far more than a dog food label ever aims at, because niacin underpins leg strength, feathering, and normal growth and metabolism in waterfowl. Pet foods simply are not built to duck specifications, so a Campbell eating them regularly runs her niacin account down. In growing ducklings the shortfall shows as weak, bowed legs; in an adult layer it can contribute to leg strain and declining condition that keepers often misread as age. Waterfowl feed or a suitable all-flock ration covers this need by design, which is the simplest reason to keep the duck on duck feed.
Water, swallowing, and why dry pet kibble suits ducks badly
A Khaki Campbell duck has no teeth and swallows food with the help of water, dabbling and rinsing as she eats. Dry pet kibble offered away from water is a poor physical match: hard pieces are awkward to swallow, and a duck trying to bolt dry food can struggle. A laying Campbell also needs a dish of oyster shell or limestone grit within reach, because the calcium in a maintenance ration rarely covers an egg a day, and pet food contributes nothing useful on that front.
What a laying Campbell should get instead
Feed a Khaki Campbell a proper waterfowl layer ration, or an all-flock feed paired with free-choice oyster shell, available through the day. Ducks eat in bouts between swimming, preening, and foraging, so constant access near deep drinking water suits them better than timed meals. Keep dog and cat bowls inside the house or in a run the ducks cannot enter, because a Campbell is bold, quick, and entirely willing to steal.
Signs to watch if a Campbell has been eating pet food
If a Khaki Campbell duck has been filling up on pet food, watch for laying that tails off, eggs with thinning shells, reluctance to walk far, legs that look strained after swimming, or weight creeping onto a breed that should stay trim and active. A duck that goes off her proper feed entirely, stops laying abruptly, or seems to struggle swallowing deserves prompt attention. A veterinarian familiar with poultry or waterfowl is the right call when legs weaken or condition falls, and it helps to say plainly what the bird has been eating and for how long, since diet history is often the missing clue in duck cases.
Assigning duck duties so the right feed lands in the dish
Campbell flocks are often fed by whoever passes first, and that is how a dog bowl ends up topped up in the duck run. KinsLe's Care Teams let you set out the flock's waterfowl feed, water changes, and shell checks as assigned tasks for specific helpers, each marked complete with a timestamp, so the ducks get duck feed whoever is on chores.