A study of field turkeys was undertaken in order to determine the invo
lvement of relative immunological differences in the etiology of turke
y osteomyelitis complex (TOC). Lame and normal turkeys were sampled fr
om commercial flocks just prior to processing in two separate trials.
After testing for functions of both humoral and cellular immunity, the
turkeys were necropsied and examined for lesions of TOC. There were s
ignificantly higher relative spleen and liver weights and significantl
y lower body weights and relative bursal weights in birds with TOC. Th
e birds with TOC had lower response to phytohemagglutinin-P in both in
vivo and in vitro tests as well as lower circulating lymphocyte count
s and higher monocyte, heterophil, and total white blood cell counts.
There was a significantly higher antibody response to sheep red blood
cells in turkeys with TOC, whereas antibody response to Salmonella pul
lorum antigen was not different. There were no significant differences
in the percentages of mononuclear cells or heterophils able to phagoc
ytize bacteria or latex particles, or kill bacteria; however, the hete
rophils from turkeys with TOC lesions did phagocytize significantly fe
wer latex particles per cell than did those of the healthy turkeys. To
tal serum protein, uric acid, and blood urea nitrogen levels were high
er in birds with TOC, whereas hemoglobin, iron, alkaline phosphatase,
and gamma-glutamyl-transferase levels were lower. Although many of the
differences in birds with TOC could be caused by the normal host reac
tion to infection, further study may reveal innate differences that co
ntribute to susceptibility to TOC.