Morphological changes in heart and lungs of broilers experiencing pulmonary hypertension syndrome caused by Enterococcus faecalis.

In a previous report, a method of identification of birds experiencing early symptoms of pulmonary hypertension syndrome (PHS) caused by challenge with Enterococcus faecalis was delineated. This method involved subjective heart scores based on visual observation of a cavity on the external surface of the right ventricular wall (RVW), as well as tonicity and thickness of this wall. Accuracy in identifying birds 48 h postchallenge with E. faecalis was acceptable. However, this method did not attempt to offer other morphological or physiological characteristics for further understanding the etiology of PHS. In the present study, three trials were conducted to establish morphological characteristics of the heart from birds challenged with E. faecalis. In Trials 1 and 2, discrepancies were found in heart length (HL) and thickness of the RVW. In Trial 3, the dry weight of the right ventricle (RV) increased after challenge with E. faecalis, as was the ratio of the mass of the RV to the mass of the total ventricle (TV). Histopathological evidence of hearts and especially lungs of birds challenged with E. faecalis were suggestive of PHS. Results indicated that RV, RV:TV ratio, and histopatholgical evaluation of heart and lungs are complementary to diagnosis of PHS.