Agriculture Reference
In-Depth Information
5
There was a strong statistical interrelationship between
abscesses found in combination at tail/lungs, tail/
vertebrae, tail/legs, tail/ribs and tail/peritoneum.
As stated earlier, the following are the two most
important questions to be answered.
Is the lesion localised or generalised?
A study of the literature indicates that it is most likely
that infection spreads from the tail of a pig to the pelvis
via the local lymphatic system, from the tail to the lungs,
ribs and legs via the bloodstream and from the tail to the
spinal vertebrae via the cerebrospinal fluid. This would
indicate the following in terms of condemnation:
•
Abscesses at a single site
: Condemnation of the part is
usually sufficient, after careful examination of the rest
of the carcase and the viscera.
•
Abscess in the tail and one or more in the spinal verte-
brae
: Remove the tail and the spinal column only.
•
Abscess in the tail and one or more in the lungs, ribs,
peritoneum or forelegs
: Condemnation of the carcase is
justified.
•
Abscess in the tail and hindleg
: Local condemnation
may be sufficient.
•
There is no apparent interrelationship between
abscesses in the head or the neck and those elsewhere,
for example, the tail or lungs, so only local condemna-
tion is indicated.
•
A statistically significant interrelationship was dem-
onstrated between abscesses in fore- and hindlegs. In
each case, the aetiology must be considered before
a judgement can be made. If, for example, the cause
is thought to be rough floors and there is no evidence
of haematogenous spread, local condemnation may
suffice.
Figure 9.14
Bovine spinal abscess associated with an infected
carpus (Courtesy of G Rankin, OV, DARD).
umbilical vessels and
systemic
navel ill where lesions
were present in the liver and/or other viscera and the
carcase as well as the umbilical tissues. Localised navel ill
constituted about 75% of all navel ill cases.
Arthritis
A small quantity of blood-tinged fluid in a joint is nei-
ther unusual nor significant. In all but the most acute
cases, the causative agent cannot be cultured from the
fluid found in the joint; it can only be isolated from the
synovial membrane. Most authorities consider arthritis
to be a quality rather than a food safety issue.
However, on either safety or aesthetic grounds, the
following can be used as a basis for judgement:
•
If there is purulent material present, the limb should be
condemned to the joint above the one affected.
•
The limb should be condemned if there is iliac, pres-
capular or prepectoral lymph node involvement.
•
If three or more limbs show lymphatic involvement,
the carcase warrants rejection.
•
If the popliteal lymph node is enlarged but the iliacs are
normal, it may be sufficient to reject only the lower limb.
•
If there are systemic changes in the viscera indicating
that the arthritis is generalised or acute, the carcase
and viscera should be condemned.
Is the lesion acute or chronic?
If an abscess is in the acute stage of development, in that
there is poor or no capsule formation, accompanied by
systemic changes, it will usually be necessary to totally
condemn the carcase and viscera (Fig. 9.14).
Omphalophlebitis
Omphalophlebitis or navel ill is a relatively common
post-mortem finding in countries where very young
calves, 4-8 days old, are slaughtered. A study in New
Zealand (Biss
et al.
, 1994) suggested that there was
histopathological evidence that a low-grade bacteraemia
was present in approximately 25% of these calves and
that routine condemnation of the carcase was justified in
extended
or
systemic
, but not in
localised
cases.
Localised
was defined where lesions were restricted to the umbili-
cus,
extended
where lesions were also evident in the
Oedema
In the healthy animal, there is osmotic equilibrium
between intracellular and extracellular parts.
Disturbances of water and sodium homeostasis
(sodium retention), hydrostatic pressure or decreased
plasma pressure, hypoproteinaemia, heart or kidney
failure, lymphatic obstruction, etc. lead to the accumu-
lation of fluid in the intercellular spaces and cavities of
the body.
