Given her history, the acuteness of the mortality, the
presenting signs and the species affected, a case of
anthrax was initially suspected and the carcass was
treated as such until tests proved otherwise.
A Diff-Quick stained peripheral smear, using blood
from the ear, was evaluated at the ranch. The
presence of large, dark blue, brick-shaped organisms
forming short chains was highly suspicious of anthrax
as described by De Vos and Turnbull (2004) and
the Office International des Epizooties (OIE) World
Organisation for Animal Health Terrestrial Manual
(2012). Smaller Clostridium spp. organisms (dark blue
staining rods) were also noted on the slide.
Initial Differential Diagnosis
A haematogenous cause of death was suspected and
suspected causes included:
Further Testing
Following consultation with the state veterinary
services in Grahamstown, anthrax was considered
‘highly unlikely’ and the mortality was more likely
associated with a larger Clostridium spp. commonly
seen in routine post mortems (MSD Animal Health,
2017).
Therefore, the carcass was moved to the state’s post
mortem facility to undergo further blood smears and
a thorough post mortem if still deemed safe to do so.
A peripheral smear using blood from the ear was
made and stained using polychrome methylene blue
(MacFadyean’s reaction) according to the Office
International des Epizooties (OIE) World Organisation
for Animal Health Terrestrial Manual (2012) methods.
This staining method confirmed the absence of a
pink staining capsule around the bacilli and therefore
anthrax was ruled out as the cause of death. A
thorough post mortem was subsequently performed.
Post Mortem and Sampling
The findings of the post mortem are summarised in
Table 1.
Site of carcass discovery with evidence of
paddling motions prior to death.
• Anthrax (Bacillus anthracis)
• Clostridium perfringens Type B (Enterotoxaemia )
or D (Pulpy Kidney)
• C. chauvoei (Blackquarter)
• Other Clostridium species (C. novyi or C. sordelli)
• Pasteurella haemolytica
• Ehrlichia ruminantium (Heartwater)
• Severe tick toxicosis
• Epizootic Haemorrhagic Virus
• Other causes of sudden mortality e.g. Lightning
strike
Un-clotted blood was initially aspirated from the
jugular vein using a 20 ml sterile syringe with an 18
Gauge needle. This blood was sent off for aerobic
and anaerobic bacterial culture as well as typing of
Clostridia spp. using multiplex Polymerase Chain
Reaction (PCR) as described in Ahsani et al. (2010).
Tissue samples measuring 1 cm 3 (trachea, heart,
lung, liver, spleen, kidney, GIT, lymph nodes, skeletal
muscle, adrenals) were collected and stored in
10% buffered formalin for histopathology. Stained
peripheral blood, brain and splenic impression smears
were made to evaluate for Ehrlichia spp, Anaplasma
spp, Babesia spp or Theileria spp. while sterile swabs
from the lung were taken for aerobic bacterial culture
and faeces was collected for routine parasitology.
Table 1. External and internal findings of the kudu cow
post mortem:
2017
December
13