Felis ISSN 2398-2950

Flat-chested kitten and pectus excavatum

Synonym(s): Swimmer, funnel chest

Contributor(s): David Godfrey, Geert Verhoeven


  • The two most common malformations of the chest in kittens are pectus excavatum ("funnel chest") and flat chested kitten syndrome (FCK).
  • Pectus excavatum (PE) is a congenital malformation of the sternum and costochondral cartilages causing narrowing of the chest ventrodorsally or sternal depression. Chest compression may reduce pulmonary and cardiac function.
  • In FCK, the ribcage angles sharply at the costochondral junction and the chest is flattened ventrally.
  • The two conditions may occur concurrently.
  • When a FCK also has weak, splayed legs, it may be known as a "swimmer"  Swimmer syndrome 01 .



  • Congenital (but some develop after birth).

Predisposing factors


  • Many theories as to cause of flat chests including genetic, nutritional, or environmental but no definitive cause identified.
  • Suggested causes of pectus excavatum include congenital predisposition, abnormal intrauterine pressure, abnormal ligament development (ie shortened central diaphragmatic tendon or thickened substernal ligament), abnormal osteogenesis and chondrogenesis.
  • May also be secondary to upper respiratory obstruction (as a result of negative intrathoracic pressure), environmental factors, and posturing difficulties.


  • Weakness of costochondral muscles and diaphragm.
  • Expansion of lungs is poor.
  • Compression of the heart may occur.
  • Role of negative intrathoracic pressure supported by the over-representation of pectus excavatum in brachycephalic breeds.


  • Usually apparent within 10 days of birth.
  • Flat chests in mildly affected animals will often resolve spontaneously, especially if nutritional intake is adequate, sometimes to the point where it is hard to detect the abnormality in the adult.
  • Pectus excavatum will not resolve spontaneous and may progress.


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Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Crigel M H, Moissonnier P (2004) Pectus excavatum surgically repaired using sternum realignment and splint techniques in a young cat. JSAP 46 (7), 352-356 PubMed.
  • Sturgess C P, Waters L, Gruffydd-Jones T J et al (1997) Investigation of the association between whole blood and tissue taurine levels and the development of thoracic deformities in neonatal Burmese kittens. Vet Rec 141 (22), 566-570 PubMed.
  • Soderstrom M J, Gibson S D & Gulbas N (1995) Fatal reexpansion pulmonary edema in a kitten following surgical correction of pectus excavatum. J Am Anim Hosp Assoc 31 (2), 133-136 PubMed.
  • Sturgess C (1995) Flat chested kittens - does taurine have a role to play? Burmese Cat Club News (UK), 12 (8).
  • Boudrieau R, Fossum T W, Hartsfield S M et al (1990) Pectus excavatum in dogs and cats. Comp Contin Edu Pract Vet 12 (3), 341-355 VetMedResource.
  • Fossum T W, Boudrieau R J, Hobson H P (1989) Pectus excavatum in eight dogs and six cats. J Am Anim Hosp Assoc 25 (5), 595-605 VetMedResource.
  • McAnulty J F, Harvey C E (1989) Repair of pectus excavatum by percutaneous suturing and temporary external coaptation in a kitten. J Am Vet Med Assoc 194 (8), 1065-1067 PubMed.