Interactions between ingested lead, lead-iron and iron shot and Pasteurella Multocida in mallard ducks
Date
1979
Authors
Journal Title
Journal ISSN
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Publisher
ORCID
Type
Degree Level
Masters
Abstract
This project included (a) experiments to define the gross,
microscopic and hematologic changes associated with lead poisoning
in 5 and 18-week-old mallard ducks, (b) experiments to define the
gross and histologic changes associated with Pasteurella
multocida
(P-19781-2) infection (avian cholera) in mallard ducks, (c) experiments
to study possible interaction between ingested lead, lead-iron and
iron shot and P.
multocida
infection in mallard ducks and (d) an
experiment to determine the effect of various concentrations of lead,
as lead acetate, on the in
vitro growth of
P. multocida
on blood agar culture plates.
Young mallards were less vulnerable to the effects of lead than
were older mallards. Birds fed whole mixed grain had increased
mortality and a higher prevalence of lesions than did ducks fed a
commercial ration. The retention of pellets in the gizzard of 18-
week-old mallards was greater than was shot retention in 5-week-old
birds, but no difference was observed in the dissolution rate of shot
between the two age groups. The dissolution rate of lead pellets
approximated 6.7 mg/pellet/day. Blood lead concentrations in lead and
lead-iron dosed ducks peaked at approximately day 9 post-dosing and
then declined. Blood lead concentrations in the ducks were several
times higher than those reported in lead-poisoned mammals, but the
soft tissue lead retention in the birds was comparable to soft tissue
lead retention in mammals. Demyelinating peripheral neuropathy and
focal encephalopathy were observed in lead-dosed mallards that were
in good body condition, not anemic and feeding normally.
Inoculation with Pasteurella
multocida (P-19781-2) produced
septicemia in mallards that died acutely and chronic localized lesions
in surviving birds. P.
multocida could be cultured from localized
lesions which supported the concept of a "carrier" state. A dosetime-
mortality response was observed in P.
multocida infection trials.
None of the shot types tested increased the susceptibility of
mallard ducks to P.
multocida. Shot types containing lead had a
protective effect against infection that appeared related to blood
lead concentration. In
vitro experiments showed that lead, at
concentrations equivalent to the blood lead concentrations in leadpoisoned
birds, inhibited growth of P.
multocida on blood agar plates.
A similar bacteriostatic action of lead was postulated to explain
the in vivo
results. Birds pre~dosed with lead shot had histologic
evidence of degenerative changes in lymphoid tissue, spleen and bursa
of Fabricius. The possible significance of these morphological
changes was discussed.
**NOTE: There was no page 161 in the original thesis**
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Degree
Master of Science (M.Sc.)
Department
Veterinary Pathology
Program
Veterinary Pathology