Endocardial fibroelastosis

From Dog
Gross specimen showing endocardial fibrosis of the left ventricle[1]
Photomicrograph of the myocardium from the left ventricle of a 12-week-old Weimeraner, showing endocardial fibroelastosis. Note the thick fibrous band under the endocardium and the associated degenerating myocardial cells.[2]

Endocardial fibroelastosis is a congenital heart disease of dogs characterized by juvenile-onset congestive heart failure.

This may also be a secondary disease, occurring in conjunction with other cardiac abnormalities and may affect both the left and/or right ventricles.

Clinical signs are usually severe in onset and commonly seen at a young age (often 4 - 6 months of age) and develop rapidly[3].

Generalized weakness, exercise intolerance, syncope, ascites, hepatomegaly and pale mucus membranes are present. A cough may be present intermittently. Tachypnea, tachycardia and a bounding pulse are frequently observed in advanced cases[4].

A tentative diagnosis can be established by auscultation of a holosystolic heart murmur and radiographic evidence of cardiomegaly and pulmonary edema[5].

A definitive diagnosis requires postmortem examination of the heart.

Gross and histological examination of the heart often reveals a diffuse fibroplasia over the ventricular endocardial surface with microscopic bands of mature fibrous connective tissue in the myocardium of the left ventricle. The fibroplasia frequently extends into the adjacent myocardium associated with cardiomyocytic and Purkinje fibre degeneration.

A differential diagnosis would include ventricular septal defect[6], double-chambered right ventricle[7], hyperthyroidism, cardiomyopathy, endocardial amyloidosis, endocarditis, mitral valve endocardiosis, other causes of congestive heart failure and infections with Dirofilaria spp.

A possible association with canine parvovirus infection has been postulated by not proven[8], and seems unlikely due to the absence of any microscopic inflammatory disease associated with this condition.

Treatment is usually conservative, with management of the secondary congestive heart failure using furosemide and pimobendan.

Surgical correction can be performed at specialty referral centers via balloon valvuloplasty.


  1. Wikidoc.org
  2. Bentley DM (1999) Congenital endocardial fibroelastosis in a dog. Can Vet J 40(11):805-807
  3. Lombard CW & Buergelt CD (1984) Endocardial fibroelastosis in four dogs. J Am Anim Hosp Assoc 20:271-278
  4. Eliot TS et al (1958) First report on the occurrence of neonatal endocardial fibroelastosis in cats and dogs. J Am Vet Med Assoc 133: 271-274
  5. Larsson MH et al (1997) Endocardial fibroelastosis in a dog. J Small Anim Pract 38(4):168-170
  6. Guglielmini C et al (2002) Atrial septal defect in five dogs. J Small Anim Pract 43(7):317-322
  7. Fukushima R et al (2011) Epidemiological and morphological studies of double-chambered right ventricle in dogs. J Vet Med Sci 73(10):1287-1293
  8. Levin S (1980) Parvovirus: a possible etiologic agent in cardiomyopathy and endocardial fibroelastosis. Hum Pathol 11(5):404-405