Vet Diagnostix
Mycotic Rumenitis in a Blesbuck
Dr Rick Last – BVSc; M.Med.Vet (Pathology)
Specialist Veterinary Pathologist
Vetdiagnostix – Veterinary Pathology Services
We were presented with a carcass of an adult female
Blesbuck which had died acutely on a game farm in
the Natal Midlands. The most striking feature of the
post mortem was a severe acute infarctive rumenitis
with multifocal to coalescent areas of red to black
discoloured rumen wall affecting primarily the ventral
sac of the rumen, reticulum and omasum (See Figure
1). There was an associated severe fibrinopurulent
peritonitis with large mats of fibrin with omental
adhesions on the rumen surface.
These fungi involved are opportunists and usually
include the zygomycetes of the Order Mucorales,
genera; Mucor, Rhizopus and Absida and Order
Entomophorales, genera; Basidiobolus and
Conidiobolus.
These fungi cannot be distinguished in histological
sections. These saprophytic moulds are associated
with decaying material, water, soil and substrate high
in carbohydrate. They are opportunistic invaders with
predisposing factors in domestic ruminants including
antibiotic therapy, rumenal acidosis, reflux of acidic
abomasal content and erosive viral diseases (MCF, IBR,
BVD, EHD).
Occurrence in a free range Blesbuck on veld would
most likely be associated with some nutritional or
environmental factor/s that have induced rumen
stasis with rumen wall irritation and secondary
invasion by these saprophytic fungi. In the days prior
to this animal being discovered, a cold front with
heavy rain had occurred.
Figure 1
The gross appearance of the rumen pathology is
typical of that expected with mycotic rumenitis which
is essentially a blood vessel associated condition due
to invasion of blood vessels by the fungal hyphae
resulting in vascular thrombosis and ischemic
necrosis. Histopathological examination of the rumen
wall confirmed a mycotic rumenitis in this animal.
Mycotic rumenitis is a severe condition that is often
fatal due to the extensive forestomach wall infarction
and tissue necrosis with associated endotoxaemia.
The inflammation extends to the peritoneum, causing
hemorrhagic and fibrinous peritonitis that mats the
omentum to the rumen, as noted in this instance.
In fatal cases, most of the ventral sac as well as the
reticulum, omasum and/or abomasum are involved,
as was observed in this particular case.
2016
MAY
9