• Cause: congenital malformation, genetic problem, acquired eg biotin (vitamin B7) or manganese deficiency, inadequate nutrition, trauma, infection eg parasitic infection, poxvirus, favus.
• Signs: abnormal occlusion of the upper and lower beak.
• Diagnosis: clinical appearance, diet and husbandry history, radiography.
• Treatment: correct diet and husbandry, optimal home monitoring, beak reshaping with Dremel tool.
• Prognosis: fair; depends on cause and how well the bird can cope with beak malocclusion.

ℹ️Print off the Factsheet on Beak deformity to give to your clients.

• Beak occlusion is abnormal:
  • Scissor beak: upper and lower beak crossed over.
  • Parrot beak (mandibular prognathism): lower beak to short, upper beak overgrows.
• In severe cases may see reduced feed intake, weight loss. Severely, congenitally affected birds may be at risk of laryngeal obstruction.
• Poor feather condition due to lack of normal preening behavior.
• Abnormal interactions with conspecifics.

• Worldwide.
• Incidence of 1-3% in some indigenous breeds in China, eg Beijing-You chicken.
• Higher incidence of up to 7% in the Appenzeller Barthuhn, a local Swiss chicken breed.

• Usually young birds.
• Older birds affected with liver disease, eg hepatic lipidosis, may show abnormal beak growth.

• Some indigenous Chinese breeds reported to be genetically predisposed.
• Local Swiss breed the Appenzeller Barthuhn has a high incidence.

• Beak may require regular trimming/reshaping.
• Surgery may be required in severe cases.

• Laryngeal obstruction; affected birds should be intubated during anesthesia.

• Congenital or acquired.

General

• Imbalanced diet Nutritional conditions overview.
• Trauma.

Specific

• Improper incubation techniques can lead to beak deformities in chicks.
• Deficiencies of Dietary formulations:
  • Biotin (vitamin B7).
  • Manganese.
  • Vitamin A.
  • Vitamin D3.
• Beak injury.
• Infection:
  • Pox virus Fowl pox.
  • Favus (Trichophyton megnini) Dermatophytosis.
  • Mite infestation Dermanyssus gallinae infestation Knemidocoptes gallinae infestation Knemidocoptes mutans infestation Northern fowl mite infestation.
• Mycotoxins, causing damage to beak tissue and subsequent growth.
• Hepatic lipidosis (older hens) may lead to poor beak quality and/or beak deformity due to deficiency of amino acids needed for normal growth.
• Can be genetic problem in some breeds eg Beijing-You chicken in China, Appenzeller Barthuhn, a local Swiss chicken breed.

• Damage to germinal tissue of beak leads to abnormal growth of keratin.
• Underlying disease may lead to poor quality keratin.
• Severe infection in deeper tissues around beak may lead to abnormal keratin growth.

• May develop in chicks immediately after hatching or have a delayed onset, eg 10-12 weeks.
• Gradual overgrowth of beak following trauma, infection or toxin exposure

• Sporadic cases.

Refereed papers

• Recent references from PubMed and VetMedResource.
• Joller S, Bertschinger F, Kump E et al (2018) Crossed beaks in a local Swiss chicken breed. BMC Vet Res 14 (1), 68 PubMed.
• Speer B & Powers L V (2016) Anatomy and disorders of the beak and oral cavity of birds. Vet Clin North Am Exotic Anim Pract 19 (3), 707-736 PubMed.
• Bai H, Zhu J, Sun Y et al (2014) Identification of genes related to beak deformity of chickens using digital gene expression profiling. PLoS ONE 9 (9), e107050 PubMed.

Other sources of information

• Chitty J (2019) Disorders of the Integument. In: Manual of Backyard Poultry Medicine and Surgery. Eds G Poland & A Raftery. BSAVA, UK. pp 140-149