Clinical Examination of Farm Animals - CYF MEDICAL DISTRIBUTION

CHAPTER 8
the ventral sac. This results in mixing of reticularrumen
contents and assists the passage of the rumen
contents into the omasum. The B cycle results in eructation
and occurs at intervals of 1 to 2 minutes.
Movement is confined to the rumen and consists of a
rumen dorsal wall contraction followed by a contraction
of the ventral sac. This movement causes gas
to be displaced from the dorsal sac of the rumen to the
cardia and eructated. Eructation contractions are
independent of the mixing contractions and their
rate is dependent upon the pressure of the gas in
the rumen. Regurgitation results from an additional
ruminal contraction interposed between normal
mixing movements of the rumen. Ruminal movements
keep the oesophageal cardia flooded with
reticular fluid. Avoluntary inspiratory effort is made
with the glottis closed, the negative pressure of the
thorax is greatly increased and the reticular fluid
carrying some floating ingesta is carried up to the
pharynx.
Conditions occurring in adult cattle
Reticulum – actinobacillosis/actinomycosis infection
of the oesophageal groove, neoplasia of the
oesophageal groove, reticular abscess, reticuloperitonitis
Rumen – secondary free gas bloat, frothy bloat, ruminal
acidosis, cold water ruminal atony, neoplasia
of rumen, rumen collapse syndrome, rumen foreign
body, rumen impaction, vagal indigestion
Omasum – omasal impaction
Abomasum – right abomasal dilatation (RDA) and
torsion, abomasal rupture, left abomasal displacement
(LDA), abomasal impaction (dietary), abomasal
ulceration, abomasal neoplasia
Small intestine – Johne’s disease, salmonellosis, winter
dysentery, bovine virus diarrhoea, gut tie
(intestinal strangulation), foreign body intestinal
obstruction, intussusception, neoplasia of small
intestine, prolapse of the intestines through the
mesentery, torsion of the root of the mesentery,
small intestine rupture post calving, spasmodic
colic
Large intestine – caecal dilatation and torsion
Rectum – rectal perforation, rectal prolapse
Abdomen/peritoneum – ascites, uroperitonium, fat
necrosis, focal or diffuse peritonitis, acute pnemoperitonium
Liver – abscessation, hepatitis, cholangitis.
History
Vaccination and anthelmintic protocols may be
related to the current problem. The farm or practice
records may indicate a recurrent problem. Recent
outbreaks of disease such as salmonellosis may be
ongoing. Some diseases may be endemic, such as
Johne’s disease. Some conditions are diet related,
and recent changes in diet or management may be
implicated. Inappropriate nutrition may be the cause
of pot bellied calves. Onset of disease may be related
to the introductions of new replacement stock or
heifers joining the milking herd. In this regard biosecurity
protocols should be reviewed. The group affected
should be etablished. The time of onset, the
duration, number affected and the severity and the
signs of disease observed. Sudden changes in condition
scores, sudden drop in milk yield, or a reduction
in apppetite and food consumption, may be disease
indicators. Calving date and stage of lactation may
be significant. Left displacement of the abomasum
is most commonly diagnosed in the the first 3 weeks
post-calving in dairy cows. Poor management practices
around calving time may result in colostrum
deprivation, with a high incidence of neonatal diarrhoea
and umbilical infections.
Signalment
Many gastrointestinal conditions are age related.
Mycobacterium johnei causes clinical (Johne’s) disease
in older adult cattle, whereas rotavirus may cause
diarrhoea in calves. The class of animal and the production
level may be disease associated. Highyielding
dairy cows have an increased incidence of
primary ketosis.
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