hemorrhagic lymphadenopathy (Figure 2).
Pneumonia and/or gastroenteritis are sometimes
observed but are not usually extensive. Atypical forms
lacking throat swelling and with extensive pneumonia
and/or gastroenteritis have been documented 2, 5,
7
. Potential differentials to consider based on the
gross pathology include clostridial myositis, anthrax,
salmonellosis, mycoplasmosis (lung sickness) and
pneumonic pasteurellosis 3, 5, 7 . Histopathology is non-
specific but characterised by lesions consistent with
endotoxic shock and capillary endothelial damage 2 .
Figure 1: Prominent subcutaneous oedema of the face,
submandibular and neck. (Photo courtesy of Dr Willem
Burger).
and possibly days in damp soil or water 7, 8 . Infection
begins in the tonsil and nasopharynx, followed by
a bacteraemia with widespread dissemination of
bacteria to various body tissues. Proliferation of
bacteria in these various sites results in tissue damage
due to release of lipopolysaccharides from bacterial
cell walls and a host cytokine response with rapidly
progressing endotoxaemia. Clinical signs can appear
1-3 days after infection and death can occur within
8-24 hours after first symptoms appear 3, 5, 7, 8.
Clinical Signs
Most cases of hemorrhagic septicaemia are fatal
within 8-24 hours; many animals dying without
exhibiting any symptoms. Less fulminant infections
are associated with pyrexia, prostration, excessive
drooling, dypnea and prominent subcutaneous
oedema of the pharyngeal region, which frequently
extends to the ventral neck, brisket and face (Figure
1). In these animals where clinical signs are noted,
mortality rates are virtually 100%, even with antibiotic
therapy 5, 7, 8.
Pathology
The most common and consistent pathology at post
mortem is severe subcutaneous and intra-muscular
oedema and cellulitis involving the submandibular
region, head, neck and brisket. Fluid is frequently
blood tinged and frequently accompanied by
Diagnosis
Confirmation of diagnosis is by bacterial isolation
and subsequent serotyping of Pasteurella multocida
isolates. In the live animal heparinized blood
samples, nasal swabs and tissue biopsies from the
tips of ears are transported on ice to the laboratory
for bacterial culture. In freshly dead animals (< 4
hours) a heparinized blood sample/charcoal swab
from the heart and nasal charcoal swab should be
submitted on ice. Spleen and bone marrow are only
contaminated late in the post mortal process and so
serve as excellent post mortal sample sites for culture.
In atypical cases lung, intestine and mesenteric
lymphnode should be included 5, 7.
Treatment and Prevention
Although some antimicrobials are effective
Figure 2: Severe blood tinged subcutaneous oedema with
associated hemorrhagic lymphadenopathy (white arrow).
2017
MAY
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