The short answer for a Leghorn among household pets
A Leghorn chicken can live happily in a home with other pets, but happiness for this breed means safety plus room to be busy. Leghorns are lightweight, athletic, and famously independent layers: they forage constantly, fly better than most chickens, and prefer keeping a little distance from anything large. That flightiness is protection around other animals, yet it does not make a hen safe with a determined predator. A Leghorn lives contentedly in a mixed household when the coop and run are genuinely secure, dogs and cats are managed rather than trusted, and she has other chickens for company, because no hen thrives as the only bird.
How a Leghorn reads dogs, cats, and other barnyard animals
To a Leghorn, a dog is a threat until long experience proves otherwise, and some dogs never stop being one: breeds and individuals with strong prey drive can kill a hen during what looks like play. Cats usually lose interest in a full-grown Leghorn, which flaps, squawks, and is bigger than typical cat prey, but chicks and young pullets are a different matter entirely and must grow up behind wire. Other livestock mix easily: goats, pigs, and horses mostly ignore foraging hens, though feed rooms need closed doors because a Leghorn will raid any open bin. Ducks share a yard fine, the Leghorn usually first to flee trouble.
Housing a Leghorn so the rest of the household cannot reach her
A Leghorn's home base must be a coop and covered run that a dog cannot dig under and a raccoon-grade latch protects, because the household pets are not the only animals watching. Leghorns roost as high as they are allowed, so provide raised roost bars inside the coop and expect this athletic breed to test fences other hens respect; a run with a top, or a trimmed flight feather on one wing managed by an experienced keeper, prevents escapes into the dog's side of the yard. Nesting boxes in a quiet corner keep laying calm, and the flock needs enough feeder and waterer stations that bolder pets or bossy hens cannot monopolize them.
Introducing a Leghorn flock to resident pets
Start with the Leghorns settled in their run for a week while dogs and cats observe through wire, rewarding the dog for ignoring the birds and removing it the moment it fixates, whines, or rushes the fence. Walk the dog around the run's outside on a leash daily, closing distance only while it stays loose and bored. Cats generally teach themselves that adult hens are unrewarding, but keep them away from any brooder or grow-out pen. Supervised mingling, if attempted at all, happens in a large space with the dog leashed and the hens free to retreat to their run, and many keepers sensibly never let that final step happen.
Watching a Leghorn for stress in a multi-pet yard
A content Leghorn scratches, dust-bathes, and ranges widely, laying steadily and returning to the roost at dusk without fuss. A hen living under constant pet pressure hides in the coop, stops laying, loses feathers to stress pecking, or panics at ordinary household sounds. Repeated dog rushes at the run wire are a welfare problem even when no bird is touched, because chronic fear is its own harm. Separate the animals more strictly if a hen's laying stops or her behavior shrinks, and have a veterinarian or experienced poultry keeper check any hen that is injured, stops eating, or is found hunched and quiet.
Sharing flock rules so the Leghorn stays safe on busy days
Most Leghorn losses in pet homes happen through a moment of human confusion: a visiting relative opens the run, a child lets the dog out while hens range, or a housesitter assumes the cat rules apply to the yard. KinsLe's Family Sharing puts the flock's profile in front of everyone who helps, with the coop rules and dog restrictions written where they will actually be seen, so this active hen's safety does not depend on who happens to remember.