Pectus excavatum

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Pectus excavatum in an 8-week-old miniature Schnauzer[1]

Pectus excavatum (flat chest syndrome) is a relatively common congenital disease of dogs characterized by deformation of the sternum[2].

Although the exact cause is unknown, it is believed that unbalanced overgrowth in the costochondral regions pushes the sternum inward[3]. The congenital deformity may produce a convex (carinatum) or concave (excavatum) appearance to the ventral aspect of chest wall. Some cases spontaneously resolve as the dog matures[4].

Familial occurrence of this disease suggests a autosomal-recessive disease, but diet may also play a role in pathogenesis[5].

Pectus excavatum normally does not usually cause any clinical sign unless it severely compresses the heart and leads to heart disease such as right ventricular outflow tract obstruction[6].

Respiratory distress is the clinical sign most frequently observed. Chest asymmetry is quite variable and respiratory distress may be associated with displacement of the organs or restriction of ventilation[7]. The deformity is generally in the caudal part of the sternum, but it has been reported in the cranial part of the sternum[8].

Degenerative changes and narrowing of the intersternebral spaces usually are not significant clinically. Malformation of sternebrae may accompany other congenital anomaly such as peritoneopericardial diaphragmatic hernia.

Pectus excavatum can also develop secondary to laryngeal paralysis[9] and Labrador retriever muscular dystrophy[10].

Diagnosis is usually based on radiography, but electrocardiography and echocardiography are recommended to detect any underlying cardiac abnormalities[11].

External surgical splinting of the sternabrae is often curative and surgical correction is warranted in cases where cardiac anomalies coexist.

References

  1. Rahal SC et al (2008) Pectus excavatum in two littermate dogs. Can Vet J 49(9):880-884
  2. Fossum TW (2002) Pectus excavatum. In: Fossum TW, editor. Small Animal Surgery. 2. St. Louis: Mosby. pp:780–784
  3. Crump HW (1992) Pectus excavatum. Am Fam Physician 46:173–179
  4. Ellison G & Halling KB (2004) Atypical pectus excavatum in two Welsh terrier littermates. J Small Anim Pract 45(6):311-314
  5. Creswick HA et al (2006) Family study of the inheritance of pectus excavatum. J Pediatr Surg 41:1699–1703
  6. Gifford AT & Flanders JA (2010) External splinting for treatment of pectus excavatum in a dog with right ventricular outflow obstruction. J Vet Cardiol 12(1):53-57
  7. Fossum TW et al (1989) Pectus excavatum in eight dogs and six cats. J Am Anim Hosp Assoc 25:595–605
  8. Ellison G & Halling KB (2004) Atypical pectus excavatum in two Welsh terrier littermates. J Small Anim Pract 45:311–314
  9. Kurosawa TA et al (2012) Imaging diagnosis - acquired pectus excavatum secondary to laryngeal paralysis in a dog. Vet Radiol Ultrasound 53(3):329-332
  10. Bedu AS et al (2012) Age-related thoracic radiographic changes in golden and labrador retriever muscular dystrophy. Vet Radiol Ultrasound 53(5):492-500
  11. Fournier TE (2008) Dynamic right ventricular outflow tract (infundibular) stenosis and pectus excavatum in a dog. Can Vet J 49(5):485-487