DIAGNOSIS OF SMALL- INTESTINAL DISEASE
• Most cases of diarrhea are acute, nonfatal, self-limiting, and require only symptomatic support, nota diagnosis.
• However, some cases do need definitive diagnosis and management as they are life threatening, have an infective potential for other animals, and/or present a potential zoonotic risk to humans.
• However, some cases do need definitive diagnosis and management as they are life threatening, have an infective potential for other animals, and/or present a potential
zoonotic risk to humans.
Fecal examination
• Fecal examination is an important part of the investigation of 51 disease. Bacteriologic culture is sometimes of questionable value, but identification of parasites is important.
• Direct Smear Staining of smears for undigested starch granules (Lugol's iodine), fat globules (Sudan stain), and muscle fibers (Wright's or Diff-Quik stain) may indicate mal- absorption but is nonspecific. Fungal elements and sporulating clostridia of uncertain significance may be seen, but rectal cytology may be useful.
• Fecal Concentration Methods: For detection of most parasites, fecal
concentration methods are most rewarding. Examination of three samples by zinc
sulfate flotation enhances detection of Giardia oocysts. A direct smear,
sedimentation, or the !hermann method can identify Strollgyloides spp. larvae.
• Virologic Examination Viral diarrhea is usually acute and self-limiting and does not require a positive diagnosis. Electron microscopy can be used to identify the characteristic viral particles of rotavirus, coronavirus, and parvovirus. Fecal ELISA tests for parvovirus are also available
• Giardia Antigen A commercially available ELISA can be used to detect Giardia
antigen in feces, although PCR is likely to be more sensitive.
• Occult Blood ; This test is used to search for intestinal bleeding before melena is seen. Unfortunately, it tests nonspecifically for any hemoglobin and is very sensitive, react- ing with any dietary meat as well as with patient blood.
Therefore the patient must be fed a meat-free diet for at least 72 hours for a
positive result to have any significance.
• Fecal Calprotectin Fecal calprotectin is a useful marker of inflammation in human lBO, as the molecule represents released neutrophil-elastase activity. Dog- and cat- specific assays are required.
• Rectal Cytology At the end of the rectal examination, the gloved finger is rolled on a microscope slide and the smear stained. Although the result is often negative, or more representative of large-intestinal disease, an increased number of neutrophils may be suggestive of a bacte- rial problem, indicating the need for fecal culture.
Fungal elements may also be identified. The test is fast and simple, but in all cases, confirmatory tests are indicated.
