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Beak Deformities

Beak deformities occur somewhat commonly in chickens and can be congenital or acquired. They can be caused by a number of different factors, including poor diet, genetics, trauma/injury, disease/parasites, tumor growth, and inappropriate incubation technique. The two most common types of beak deformities are scissors beak and parrot beak.
  • Parrot beak: Parrot beak, medically referred to as mandibular prognathism, is a type of beak deformity in which the bottom half of the chicken's beak is too short, or the top half has grown excessively long.
  • Scissors beak: Scissors beak, also referred to as crossed beak, crooked beak, or lateral beak deviation, refers to a condition in when the top and bottom portions of the chicken's beak don't align correctly, and deviate laterally.
Congenital beak deformities occur as a result of genetic abnormalities, passed down by breeder chickens. These types of deformities will show soon after the chick hatches. Often, chicks which possess severe beak deformities are not able to complete the hatch process without assistance and will often die in their shell. Certain breeds of chicken are genetically more prone to beak deformities then other breeds. In China, up to 3% of some indigenous breeds such as the Beijing-You and Quingyuanma develop a beak deformity, with crossed beak being the most common. Cleft primary palate (cpp) is a chicken mutant strain which has complete truncation of the upper beak with normal development of the lower beak.

Impact of beak deformities

Chickens use their beaks for many important activities, including eating, drinking, maintaining their feather quality (preening), and for pecking (to investigate objects as well as for establishing of group social structure, "the pecking order"). Chickens with deformed beaks have reduced feed intake, growth rate, and tend to develop abnormal behaviors. The degree of impairment is generally consistent with the severity of the deformity, so a chicken with mild overgrowth may demonstrate only mild signs of impairment where a chicken with severe crossing and elongation may not be able to eat without assistance.

Clinical Signs

Abnormal or deformed beak


  • History
  • Clinical signs
  • Physical exam

Reported Cases

  • Case 1: Cross beak in a Chickens Crossed beaks have been reported to occur in Appenzeller Barthuhn, a local Swiss chicken breed. The assumed causes for this beak deformity which are also seen in other bird species including domestic chickens, range from environmental influences to genetic factors. The aim of this project was to characterize the prevalence, the phenotype, and the underlying genetics of crossed beaks in Appenzeller Barthuhn chickens Ref

  • Case 2: Keratoacanthoma beak-deformity in a Parakeet An abnormal maxillary beak growth occurred in a 6-year-old male budgerigar. Although the bird was still capable of eating, it had recently been demonstrating signs of respiratory distress and euthanasia was recommended. On histological examination, the neoplasm was dramatically effacing the normal structure of the maxilla and infiltrating into the rostral nasal sinuses. The tumour consisted of many cyst-like proliferations of well-differentiated squamous epithelial cells with central keratinization. Contiguity of the tumour cells with the stratum germinativum of the beak was noted in one microscopic field. This tumour type has not previously been reported in the avian beak; however, this case shows some similarities to subungual keratoacanthomas occurring in human patients and nailbed keratoacanthomas occurring in dogs and cats. Ref


Diet modificationSome chickens may require tube feeding, with their feed ground up (this can be accomplished through the use of a coffee grinder or blender) with water added to create a wet mash.
SurgeryMay be indicated or may be a possibility depending on the severity and cause of the deformity. Surgery should only be an avian veterinary surgeon. There are many that specialize in beak reconstructive surgeries. Use our vet directory to find them.
Beak trimmingSome chickens may benefit from periodic beak trimming. However, this should only be conducted by an avian veterinarian.
Supportive careDepending on the severity, chickens may or may not need to be kept separate from other flock members. They often do better when paired with one other chicken 'buddy' and housed separately, to ensure that they don't get picked on and are able to access food and water.
If recognized in newly hatched chicksApplying gentle outward pressure to the beak for 10 minutes, 6 to 8 times daily, may be able to correct some mild, early cases.



  • Feed a nutritionally balanced diet
  • Reduce risk of beak injury
  • If using an incubator to hatch chicks, ensure that the temperature is correct and does not fluctuate during the incubation period.


Depends on the severity of the deformity

Scientific References

Good Overviews

Age Range

Usually starts during growth.

Risk Factors

  • Vitamin D3 deficiency: Has been related to beak softening in hens and bent or malformed beaks in young chicks.
  • Manganese deficiency: Chicks that were bred from breeders with a manganese deficiency have an increased risk of parrot beak.
  • Biotin deficiency
  • Vitamin A deficiency
  • Imbalanced Calcium and Phosphorus ratio
  • Recent beak injury: Any trauma to the beak that is not treated early enough or appropriately can result in a beak deformity, especially in young, growing chicks.
  • Fatty liver disease: Occurring more commonly in older hens, this disease interferes with the metabolism of amino acids that are required for normal beak growth.
  • Improper incubation techniques: Humidity and temperature settings that are too high or too low during the incubation and/or hatching process.
  • Avian pox virus: Infection with this virus can sometimes result in beak deformities, depending on the location and severity of the pox blisters.

Case Stories