E. F. JANKUS, N. A. STALEY AND G. R. NOREN 
57 
two times, or from 10.2 to 20%, based on an 
acute phase mortality of 45% (86.8% of 52.3, 
Table I). 
The initial occurrence of VSD in the 1971 
breeding program adds a complicating factor. 
However, it would appear that VSD is an inci- 
dental finding, and that the RH and EFE devel- 
oping in the five cases from Flock 2 were 
primary lesions and not a result of the VSD. 
VSD lesions observed in these 5 cases were simi- 
lar to those reported by Einzig et al.^^ 
The RH turkey can be readily identified at 
four weeks of age by QRS frontal axis shift and 
increased QRS vector strength. The gradual re- 
turn of these parameters toward the control 
values suggests that many "recoveries" occur 
spontaneously. This observation has also been 
made by Hunsaker et al.'^ 
Occasionally a turkey with a typical RH ECG 
at three weeks will convert to control ECG val- 
ues, and have a grossly normal heart on autopsy 
at five weeks. The reverse has also been noted, 
that is : a control ECG pattern at two and three 
weeks of age, and an RH ECG pattern and le- 
sions at 5 weeks. Evidently a variation in the 
time course of the disease exists with respect to 
onset of, and rate of recovery from, the chronic 
phase. Curiously, the same ECG RH identifying 
features are present whether the heart, on au- 
topsy, has predominantly right, left or biventri- 
cular dilatation. This suggests that the ECG 
patterns currently used to identify RH turkeys 
may be primarily related to the pathophysiol- 
ogy of the conduction tissues and not to the as- 
sociated myocarditis and ventricular dilatation 
and/or hypertrophy per se. These ECG changes 
of turkey RH are more striking than the ST-T 
wave changes and left ventricular hypertrophy 
patterns reported in IC and EFE in man." !^ 
Einzig et al.,i* comparing the same group- 
ings of control and RH turkeys at 26 weeks of 
age, reported that the cardiac outputs of con- 
trol, RH-recovered and RH-live groups were 
not significantly different. Both the RH-re- 
covered and RH-live groups had increased car- 
diac filling pressures and lower systemic arterial 
pressure. The association of arterial hy- 
potension and low mean QRS vector strength of 
RH-recovered turkeys is consistent with data 
reported in a strain of hypotensive turkeys by 
Krista et al.^^ The degree of involvement of RH 
in this strain was not reported. 
Auscultation over the left rib area of a num- 
ber of RH turkeys yields a pansystolic murmur 
as in Figure 2. The conclusion that the murmur 
is mitral in origin is based upon the following : 
(1) maximal intensity of the murmur is located 
over the left rib area, (2) the association of mi- 
tral valve pathology with the disease,^ (3) ci- 
neradiographic evidence of mitral insufficiency 
(MI),^'' and (4) a reported case of RH with a 
cardiac output curve consistent with MI." The 
prominent third heart sound (Figure 2) is con- 
sistent with a diagnosis of congestive heart fail- 
ure associated with MI. The incidence of 
murmurs in RH turkeys in this study is un- 
known. However, 6 of 20 (30% ) in another group 
of RH tom turkeys at five weeks of age had pan- 
systolic murmurs as presented in Figure 2. 
Whether the mitral valve pathology is subse- 
quent to the left ventricular dilatation, or re- 
sults from primary valvulitis is unknown. It is 
interesting that only the mitral valve has been 
observed to be involved in turkey RH. The asso- 
ciation of MI and cardiomyopathy in man is 
also recognized by investigators. ^^•^'^ 
Histological examination of hearts from the 
RH-recovered group shows lesions that are in- 
termediate between the EFE of the RH-live or 
RH-dead groups and the control turkeys. Evi- 
dence of EFE of the left ventricle persists, and 
a degree of left ventricular dilatation and hy- 
pertrophy were observed at the time of sacrifice 
(13 weeks). Morphological residual changes 
probably persist in all but the most mildly in- 
volved cases. 
Many of our turkey cases may be classified as 
IC and would fit Goodwin's^^ classification of 
primary congestive cardiomyopathy. The au- 
topsy findings of a wide spectrum of ventricular 
dilatation and EFE in turkey RH suggest that 
the presence of EFE may be secondary to 
the myocarditis. The hypothesis of Black- 
Schaffer^'' that EFE is the result of dilatation 
of a high pressure pulsatile chamber appears to 
be valid for turkey RH. 
The presence of myocarditis and virus-like 
particles in the embryos and turkeys from this 
experimental flock, as previously reported, '' ^o 
is consistent with in ovo transmission of the 
