The pathology of organomercurial poisoning in swine
Date
1968
Authors
Journal Title
Journal ISSN
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Publisher
ORCID
Type
Degree Level
Doctoral
Abstract
The pathological and clinical features of disease in young
pigs resulting from the oral ingestion of organornercurial compounds
has been characterized and related to tissue levels of mercury. In
three experiments, the toxic effects of methylmercuric dicyandiamide
(MMD), ethylmercuric chloride (EMC) and phenylmercuric chloride
(PMC) have been studied. The experimental period lasted 60-90 days
and the dosage range studied was 0.19-4. 56 mg. Hg/kg. daily.
In general, daily dosage levels ranging from 2.28 to 4.56
mg. Hg/kg. were toxic regardless of organic form. Lower daily
dosages, 0.38 and 0.76 mg. Hg/kg. were toxic only when administered
in the form of alkyl compounds (MMD and EMC).
The primary toxic effects of these mercurial compounds was
manifested pathologically by degenerative changes in the susceptible
cells of target organs. Alkyl mercurials caused enteric, renal and
CNS disease, while aryl mercurials caused renal and enteric disease.
The analysis of levels of mercury in tissues of animals
receiving the organomercurials indicates that there is a direct association
between tissue level and evidence of injury.
The disease produced by MMD is largely one of the central
nervous system and is related primarily to neuronal necrosis.
Cortical neurons are most susceptible to injury and those in subcortical
nuclei, in spinal gray matter, and in sensory ganglia are injured
at higher doses. In the chronic form of toxicosis, there occurs, in
addition to neuronal necrosis, secondary gliosis, capillary
endothelial proliferation and degenerative arteriopathy in leptomeningeal
blood vessels supplying injured cerebral cortex.
The character of the vascular lesions in chronic MMD
toxicosis is compatible with the ones of regional hypertension.
Chronic poisoning with EMC was manifested by disease
of the CNS entirely similar to that described previously for MMD.
The subacute form of the disease seen in animals receiving higher
doses of EMC had, in addition, lesions in the large intestine characterized
by edema of the mesocolon associated with degenerative
arteriopathy in serosal vessels and pseudomembranous colitis
and typhlitis. Analytic findings indicated that, in EMC poisoning,
most tissues contained relatively high levels of mercury.
The disease occurring in PMC intoxication results from
injury to the kidney and large intestine. The primary lesions are
pseudomembranous colitis and typhlitis and nephrosis characterized
by degeneration, necrosis, and regeneration in the epithelium of
the proximal tubules. The pathology of this disease is similar to
that described for mercuric chloride poisoning and reflects the
ease with which phenylmercuric chloride is metabolized to release
free mercuric ions.
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Citation
Degree
Doctor of Philosophy (Ph.D.)
Department
Veterinary Pathology
Program
Veterinary Pathology