Ancillary gastrointestinal diagnostics in camelids (Proceedings)


Ancillary gastrointestinal diagnostics in camelids (Proceedings)

Aug 01, 2011

First compartment fluid examination

First compartment (C1) fluid examination is a diagnostic aid for animals exhibiting abdominal distension, reduced fecal output, anorexia, and abnormal first compartment texture or motility.

C1 fluid may be obtained by passage of an orogastric tube with aspiration by a dosing syringe or reversed stomach pump. The use of a weighted tube allows passage of the tube ventrally to maximize fluid obtained. This method may result in salivary contamination, which significantly affects some analytes, including pH, Na, K and methylene blue reduction time (in cattle)

First-compartment paracentesis completely avoids salivary contamination and is therefore the preferred method for pH determination. It usually results in a smaller sample volume and carries a low risk of subcutaneous abscessation and localized peritonitis. It should also be avoided in females in late gestation.

To obtain fluid in adult llamas, the site for insertion is 20cm caudal to the last costochondral junction. This endpoint should be clipped and disinfected and the animal should be well-restrained. A 16ga, 2-3" needle should then be directed dorsomedially and thrust into the first compartment. About 4-5 mL can usually be obtained by this method.

Table 1: First Compartment Fluid Reference Ranges in Llamas (Adapted)3
Once collected, the fluid should be placed in a clean vial and either analyzed immediately or kept at body temperature until timely analysis can be performed.

C1 fluid pH is best measured using a pH meter, as they are less affected by the color of the fluid, as are pH papers. A drop of fluid may be placed on a warm glass slide and examined using a microscope. On low power, numerous protozoa should be seen moving rapidly across the slide. Three sizes of protozoa should also be identified, small, medium and large. The large protozoa are the most sensitive to lactic acidosis and will be the first to be lost in cases of rumen acidosis. This slide may then be dried and Gram stained to assess ratios of G pos and G neg bacteria.

Methylene blue reduction time is determined by mixing 1 drop of 0.03% methylene blue to 20 drops of fresh fluid in a clear tube. The time taken for the C1 fluid to be decolorized back to its original color is then determined, which is the result of normal anaerobes reducing the methylene blue. Sedimentation time is determined by placing C1 fluid into a clear tube and watching for feed particles to sink to the bottom of the tube. With active fermentation, gas bubbles cause the feed to float. Samples that sediment quickly have inadequate fermentation.

C1 fluid chloride concentration is a useful test that may be submitted to a laboratory and run as a "urine" chemistry. Laboratories should be asked to specifically run a coulometric titration to determine chloride concentration, over potentiometric determination, which has been shown to overestimate chloride concentrations in rumen fluid.

C3 HCl reflux into C1 occurs due to vagal-type indigestion, small intestinal obstruction or ileus. Because of highly effective C1 buffering systems and volume, this HCl will not cause the C1 pH to change, but will alter [Cl-]. C1 [Cl-] should be interpreted carefully in animals that have received oral electrolytes.