Indications include traumatic reticuloperitonitis (TRP), abomasal ulcer, peritonitis, uroperitoneum, chronic weight loss,
abdominal mass. Three sites are recommended. The right ventral flank in front of udder just medial or lateral to caudal superficial
epigastric vein (milk vein), is the site most likely site to yield some fluid. This is the preferred site for routine abdominocentesis.
Between the xiphoid and umbilicus to the right of midline is the best site when abomasal ulcers suspected. Just behind xiphoid
is the best site best when reticulitis is suspected. The use of ultrasonography simplifies the choice of abdominocentesis
site. The supplies & equipment needed includes an 18 gauge 1.5 inch (or longer) needle, or a teat cannula and #10 blade, and
a 2 ml EDTA blood tube. The technique is simple. Restraint is applied in the form of a tail jack. When inserting the needle,
rest the hand on abdominal wall and use steady, firm pressure until the needle pops into abdomen. Stop. Wait. If no fluid
comes out, spin the needle. The needle may move as the gut moves. If no fluid comes out, advance or retract needle. Be patient.
Interpretation: Only about half of attempts yield fluid. A few drops to a few milliliters are normal. Copious fluid is abnormal.
Normal fluid has a total protein < 2 g/dl, and white cells (most of which should be mononuclears) < 5,000/microliter . Peritoneal
creatinine twice the serum creatinine indicates uroperitoneum.
Note: Cattle wall off abdominal lesions remarkably well. Fluid from different regions of the abdomen may be quite different
in character. Always attempt collection near the suspected lesion.
Cerebrospinal fluid aspiration
Indications include encephalitis, listeriosis, posterior paresis, meningitis (secondary to septicemia). The site is the lumbosacral
junction, identified by a depression just caudal to the dorsal spinous process of the last lumbar vertebra. Supplies and equipment:
needed for calves includes a 20 gauge, 1.5 inch needle while in mature cattle, a 3-6 inch 18 gauge spinal needle is required.
Block the site, superficially and deeply with lidocaine. For mature cattle, make a skin puncture with a 14 gauge needle or
a surgical blade. Angle the spinal needle cranially very slightly (about 10°). If the animal is recumbent, make sure it is
in true sternal recumbency (i.e. that the sacrum is parallel to the ground). Make sure the needle begins on the midline and
is not directed laterally. When the meninges are penetrated, a pop is felt and the animal usually jumps. Try to let the fluid
flow freely without aspiration. Don't aspirate with a lot of vacuum.
Interpretation - The sample should be at the lab in a few hours but if refrigerated it can be preserved longer. On gross visual
examination, the sample should be crystal clear. If uniformly reddish, this indicates hemorrhage (traumatic or iatrogenic).
Sometimes microscopic evaluation can distinguish between the two. If the fluid is cloudy, it may indicate meningitis. In severe
cases of meningitis, the CSF may clot. A direct smear should contain almost no cells if normal. In bacterial meningitis is
present, neutrophils predominate and maybe in sufficient quantity to be seen on a direct smear.