Cross beak, scissor beak, scissors beak, crooked beak, lateral beak deviation
General signs -
Easy to identify: when a chicken�s beak is or seems to be getting crooked in such a way that the top and bottom don�t meet up (but cross over each other), your chicken is suffering from this disorder.
This may also be accompanied by weight loss or stunted growth if the crossed beak is severe.
In some cases, this defect is caused by the chick's positioning herself incorrectly for hatching---normally, one wing will shelter the head inside the shell, but if she doesn't have her wing over her head, the skull can malform, and it will reveal itself within the first few weeks as a cross beak or scissor beak as she begins to grow. This can also commonly be caused by various nutritional deficiencies such as a lack of vitamin D, folic acid, biotin, methionine, or calcium. An injury to, or infection in, the cere can cause the development of a crossed beak, too. Birds with liver disease may develop beak (and nail) overgrowth issues as well, which can lead to crossed beaks. A crossed beak can even be a genetic issue.
However, the cause is always a little difficult to determine. Even when you have several birds with the condition, that doesn't guarantee it's a genetic problem. Consider that chicks hatched together in an inexpensive home incubator can experience the same incubation issues leading to crossed beaks. And breeding birds kept together would likely be on the same nutritionally deficient diet; this can happen when the food gets old or stale, or when free ranging breeding birds gorge on, say, fallen fruit, and don't eat enough of their nutritionally balanced feed. That means the eggs laid by birds on the deficient diet may produce several chicks with the condition. So don't assume you've got a genetic issue just because you're seeing several cases together that may be caused by improper incubation or a deficient diet.
Not communicable from bird to bird, but if diet or improper incubation is the issue, it may be common in certain populations.
Communicability to humans
Not until we grow beaks. And hatch from eggs.
If congenital (meaning if it�s an issue your chick developed in ovo due to bad positioning, improper incubation conditions, nutritional issues in the mother hen), you�ll generally see it start to develop within a week. If it�s due to injury, nutritional deficiencies in feed at home, or to liver issues, it can begin to develop at any time.
No. This is not a disease that is carried and passed to other chickens.
Yes. It may be found more in certain populations by reason of diet. Improper artificial incubation can also contribute; be sure to invest in a reliable incubator or use broody hens to incubate.
Home treatment and/or prevention
Prevention:Monitor incubation conditions carefully, and invest in a good incubator. Provide a properly balanced diet for your birds, and don�t offer treats in excess, which could throw off the balance.
Treatment: When your bird has a mild crossed beak, in most cases you'll simply have to make sure the feeder and waterer are deep enough to accommodate the way your cross-beaked chicken must eat and drink, since it can be more difficult for them. Sometimes mixing a little yogurt into her feed will help her ability to pick up the food. Other high protein foods like--believe it or not--eggs that have been hard boiled and cut finely can help, too. But do check with a vet if you notice this happening, because if it is a nutritional issue, your vet may be able to recommend changes to halt further progression, or diagnose a more serious liver ailment.
A vet may be able to diagnose the cause of cross beak, especially if it�s something your chicken is developing late, due to injury, nutrition, or liver issues. If the case is particularly severe or if your hen seems to be having trouble eating, a vet may be able to show you how her beak can be trimmed to help her, if that is necessary--although it isn't usually. Poor trimming can worsen the problem, so it�s not something to attempt on your own. This is different from the "trimming" done in factory farm operations where practically the entire beak is removed--this simply addresses the tip (like a fingernail, but not to the quick), so the top and bottom beak meet up better. Under some conditions, an avian vet may have more advanced (and expensive) methods to assist. Sometimes a crossed beak originates with an injury to or infection in the cere, causing a problem with the rate of beak growth. When the keratin in the rhamphotheca grows more quickly on one side than the other, the beak will eventually become crossed. That issue, along with malformations in the skull, praemaxilla or frontal bones, can occasionally be corrected with a prosthesis designed to address the problematic anterior growth of the upper mandible, or rhinotheca. Occasionally, it can be corrected by placing pins and using rubber bands... sort of like bird braces.
The illness can be fatal, if the bird can�t eat or drink properly; however, in most cases it�s just unsightly and can inhibit foraging and preening. However, most birds with crossed beaks can lead long, productive, and happy lives even without treatment, so long as they are given a little extra consideration at the feeder and waterer.
Other conditions, illnesses and/or diseases with similar signs:
It�s difficult to confuse crossed beak with something else, but be aware that it can be caused from underlying conditions, such as liver problems or various nutritional deficiencies. Those should be addressed in addition to addressing the crossed beak itself.