Simple procedures for complicated cases (Proceedings)

Abdominocentesis

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.

Lumbosacral anesthesia

Follow the same procedure as above. For epidural anesthesia, withdraw the needle into epidural space or try not to advance past the epidural space during placement. Administer 2% lidocaine, add a dose of 0.1 ml/kg of bodyweight. For spinal anesthesia, administer one half of that amount into the sub-arachnoid space. Anesthesia and paresis of the hind limbs, tail and caudal abdomen (up to the umbilicus) will be achieved. The head should remain elevated for 15 minutes after administration to prevent anesthesia of the brain.

Indications include surgery of the perineum, hind limbs and caudal abdomen.

Liver biopsy

Indications include fatty liver, other liver disease, and assessment of copper status. The site for biopsy is on the right side at intercostal space 9 or 10 just above or on a line from the tuber coxae to the elbow. If available, ultrasonography can be used to locate the liver.

Supplies needed include local anesthetic, a #15 (or #10) blade, a biopsy needle, and 10% formalin. The technique requires restraint in a chute. Anesthetize the subcutis and intercostal tissues with lidocaine. Then make a small incision over the rib, slide the skin cranially, and insert the needle just off the cranial edge of rib. Aim at left shoulder. Pop through diaphragm then advance the stylet, followed by trocar. Tease the liver core off the stylet with a needle. Place it in formalin for histopathology or a vacuum tube for Cu analysis if desired. The use of ultrasonography allows one to choose any intercostal space under which the liver can be visualized.

Arthrocentesis/joint lavage

Indications include septic or inflammatory arthritis. Supplies needed are needles (1.5 inch, 18 gauge or larger), an IV set, sterile LRS, a means to pressurize a fluid bag, slides, stain, and a microscope. The site and technique are slightly different for different locations, and require regional or general anesthesia, tranquilization or other secure restraint. The area is surgically prepared. (Personal opinion - A wide clean area with clean drapes and attention to cleanliness is probably more important than a small, meticulously prepared aseptic area surrounded by filth). The first needle is placed into joint capsule and the sample collected. If culture is desired, put part of the sample in a blood culture bottle. The remainder can be used for fluid analysis or simply cytologic examination. If lavage is to be performed, attach the fluid source and distend the joint. Place a second needle as far as possible from the first. Using pressure, flush LRS through the joint, occasionally occluding one needle to allow distension of the joint. Half way through the procedure, attach the extension set to the second needle and reverse the flow. When the lavage is finished, instill antibiotic into the joint. Bandage the needle puncture sites.

Interpretation: Normal synovial fluid is clear, amber and viscus. Thin watery fluid, elevated WBC count, etc. indicate inflammation but not necessarily infection. Use the history, clinical signs, differential and bacteria on cytology, and culture to help confirm sepsis. Normal fluid has few cells - < 5,000/ microliter. If numerous cells are seen on a direct smear, and there are more neutrophils than mononuclears, the joint is inflamed and may be infected.

Intravenous digital anesthesia/antibiotics

Indications include surgery of the foot and extensive deep trimming and paring for both or either. Infections of the bones, joints and soft tissues of the hind limb are indications for antibiotic injection. Any digital vein is an acceptable site. Supplies and equipment needed are a tourniquet, a tilt table or chute, and a 20(or smaller) gauge needle or butterfly set. The technique is the same for anesthesia or antibiotics. Clip and prep area over vein. Apply the tourniquet, palpate the vein and insert the needle. Infuse 20 ml lidocaine for anesthesia. Florfenicol at 2 mg per kilogram has been recommended. Remove tourniquet in 15 minutes for antibiotics or after the procedure for anesthesia.

Catheterization of auricular vein

Indications include any time the administration of IV fluids or drugs is desired. Any dorsal auricular vein is an acceptable site. Supplies required include a catheter (2 inch, 14 gauge or smaller), elastic band, hemostat, tape, injection cap, heparinized saline, and "super glue". Clip and prep the ear for catheterization in the usual manner. Place the band around the base of ear as tourniquet and clamp with a hemostat. Enter the vein as far distal as possible so that the catheterized part of the vein is straight and is not going to kink when the ear moves. Remove the tourniquet and attach an injection cap, flush with heparinized saline, and superglue the catheter and cap to ear. Tape the unit in place with a simple bandage. Flush at least twice a day with "hep saline".

Ruminal fluid analysis

Indications: Acidosis, indigestion, vagal indigestion. Supplies include a weighted collection tube or needle and syringe. The tube technique , involves passing a tube with a weighted end into the rumen and aspirating to form a siphon. Collect the first 100 ml or so in one cup, then switch to another and collect more fluid. If a sufficient quantity is collected in the second cup, then discard the first cup. The currently preferred method for evaluating the Ruminal fluid of herds suspected to suffer from chronic acidosis is to aspirate transabdominally through the left flank using an 16-18 gauge needle 3" needle. This method eliminates the possibility of salivary contamination.

Analysis and interpretation: Color, odor and smell should be evaluated immediately. Normal color is gray-green to green to brownish yellow depending on the diet. Milky gray or yellow fluid is associated with CHO engorgement. Cattle on high carbohydrate diets have lower pH values than those on roughage diets. Acid pH of less than 5.5 is diagnostic of ruminal acidosis. On a herd basis, the test can be used to evaluate the feeding program. See other references for details. Ruminal pH of greater than 7.0 indicates ruminal alkalosis. Simple ruminal inactivity or anorexia will result in ruminal alkalosis.

Methylene Blue Reduction time (MBR)-The greater the metabolic activity of the ruminal flora (and the greater the CHO content of the ration) the shorter the time required for the blue dye to clear. MRB test measures the redox potential of the rumen. One part 0.03% methylene blue is added to 20 parts strained ruminal fluid. A second tube of ruminal fluid serves as a control. Clearing of the dye in 5-6 minutes indicates active ruminal flora. Delayed clearing indicates diminished activity. Ruminal chloride is elevated in abomasal impaction in cattle and abomasal emptying defect in sheep. (< 30 meq/L is normal)

Microscopic examination - Direct microscopic examination of a drop of fresh fluid on a slide is a quick and useful way to assess rumen function. Estimate the number and types of organisms; an exact count is unnecessary. Normally, abundant, live, active protozoa of various size and species will be present.

The ratio of Oligotrichs to Isotrichs varies with diet. Very large Oligotrichs are the most fragile species; their presence suggests a healthy rumen. Lugol's stain kills the protozoa and stains carbohydrate in protozoa and bacteria. Gram's Stain - A normal ruminal bacterial population should be primarily gram negative and should include many different types of organisms. Gram positives increase in relative number as CHO increases in the ration. In CHO engorgement, Strep bovis then Lactobacillus become the predominant bacterial type.