Clinical Examination of Farm Animals - CYF MEDICAL DISTRIBUTION

CHAPTER 8
colourise in 3 minutes or less; rumen fluid from cattle
on a hay only diet will decolourise in 3 to 6 minutes. A
time of 15 minutes to decolourise would indicate
poor microbial activity.
Protozoal activity
Rumen fluid from normal healthy cattle contains
high numbers of large and small protozoa with
ciliate and flagellate forms. They are highly active.
The sample should be agitated to resuspend the organisms.
A drop of the sample should be placed on a
warm glass slide and covered with a coverslip. The
protozoan activity can be observed using the low
power ¥10 objective lens. Large protozoa are more
sensitive to disturbances. All protozoa are killed
when the pH drops below 5. There are reduced numbers
in samples with low fermentation activity.
Gram staining
Gram stained smears from rumen fluid samples
can be prepared. There are mainly Gram negative
bacteria in normal rumen fluid, but in ruminal
acidosis Gram positive streptococci and lactobacilli
predominate.
Rumen fluid chloride concentration
This can be measured by most laboratories on request.
In healthy cattle, rumen fluid has a chloride
concentration of less than 30 mmol/l. Concentrations
above this level are considered abnormal and
may be caused by reflux of abomasal ingesta into the
rumen. High levels also occur in ruminal acidosis
and severe anorexia.
Exploratory laparotomy and
rumenotomy
Exploratory laparotomies can be extremely useful
in confirming and correcting some conditions of
the abdomen. Laparotomies are carried out on either
the right side, the left side or the midline, depending
upon which conditions are suspected. A left-sided
laparotomy may include a rumenotomy. Left-sided
laparotomies enable the following structures to be
palpated: the rumen, the reticulum, the spleen, the
left border of the liver, part of the diaphragm, the apical
beat of heart, the left kidney through peritoneal
fat, the path of ureters, the bladder, the uterus, the
right and left ovaries, and the descending colon.
Adhesions of the reticulum to the parietal peritoneum
may be palpable in traumatic reticulitis. A
left displaced abomasum can also be confirmed. A
rumenotomy can be performed during a left-sided
laparotomy and can confirm the presence of an obstructive
foreign body, such as ingested plastic bags
or hay nets. The reticulum, rumen, oesophageal
groove, reticularomasal orifice and cardia can be
examined. The reticulum should be very carefully
examined for penetrating foreign objects, abscesses
and Actinobacillus infections of the oesophageal
groove. A right-sided laparotomy gives access to the
omasum, the abomasum, the spiral colon, the duodenum,
the jejunum, the ileum, the caecum, the liver
and gall bladder. Surgery will enable confirmation of
a dilated caecum or torsion of the caecum, a right displaced
abomasum, an intussusception and torsion of
the root of the mesentery.
Abdominocentesis and peritoneal
fluid analysis
Analysis of peritoneal fluid can be diagnostically
useful to rule in or rule out abnormalities within
the abdomen. It is useful in diagnosing peritonitis in
conditions such as traumatic reticulitis, abomasal
ulceration and intussusception; uroperitoneum in
conditions such as a bladder rupture or a ureteral
rupture; gut contents in the peritoneum caused by an
intestinal rupture; haemorrhage into the peritoneum
caused by abdominal tumours, hepatic and spleenic
ruptures, and ascites caused by right-sided heart
failure.
Abdominocentesis
Abdominocentesis is easy and inexpensive to perform,
and requires little equipment. In normal
healthy cattle there is usually only 15 to 20 ml of peritoneal
fluid in the peritoneal cavity. As a consequence
a sample is not always obtained and the lack
of a sample should not be interpreted as abnormal.
The only exception to this is during late pregnancy
when the volume increases markedly. Abnormal
peritoneal fluid, particularly in cases of local peritonitis,
may be confined to a small area of the peri-
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