Cross beak (also called scissor beak or crossed beak) is a condition found in chickens where the upper beak and lower beak are not correctly aligned and they overlap each other. This malformation prohibits the bird from closing its mouth properly, which makes it difficult for the bird to eat and drink. In most cases, a chick with cross beak can live a full, happy life but may need a few special considerations so that it may thrive.
Cross beak can be evident at hatch or develop later on as the chick matures. It is difficult to know the exact cause, but generally when a crossed beak is evident at hatch the cause is suspected to be a possible genetic issue, a malposition of the chick inside of the hatching egg, or improper incubation conditions. When a crossed beak develops around 4-12 weeks of age, the cause may be due to injury or a nutritional deficiency. Any injury to the skull or face as a young chick can lead to a misalignment of the jaw, which may cause a crossed beak to form. Adding younger chicks to an established flock can lead to hens pecking the younger birds, which may lead to the development of cross beak.
In most cases, a chicken with cross beak can live without issues, but you will need to monitor her body condition and make sure she's able to eat and drink. Chickens with cross beak are usually smaller than the other birds the same age because they are unable to eat as efficiently. The upper and lower beak misalignment makes it nearly impossible for a chicken to pick up pieces of feed and she adapts by using the lower beak as a scoop. Layer mash is a better choice of feed than pellets for a bird with cross beak. Adding water or yogurt to the layer mash may also help a cross beaked chick better scoop up the wet mash.
In rare cases, a cross beak may be severe enough to require routine beak trimming. A chicken's beak grows continuously and it wears down as she pecks and eats. A bird with a crossed beak will not have this normal wearing activity and may benefit from having a paver or brick in her yard to rub her beak on to help. If she is not able to keep it worn down, a beak trim may be needed. To trim a beak, carefully wrap the bird in a bath towel to secure her wings and feet. Using a pair of dog toenail trimmers, carefully and gently trim the ends of both the upper and lower beak as needed to help bring them into better alignment. Then use an emery board to file off any rough areas after trimming the beak. Be sure to also have cornstarch close by when trimming a beak. There is a "quick" in a hen's beak and if you trim too closely it can bleed.