**4.4 Biochemical changes**

Hall [55] suggested that panhypoproteinemia (hypoalbuminemia and hypoglobulinemia) was typical of protein-losing enteropathy (PLE) and also reported that hyperglobulinemia was noticed in intense inflammatory conditions. Hinton et al. [8] recorded hypoproteinemia and hypocalcemia in gastroduodenal ulcer dogs. Measurement of the serum concentration of unconjugated bile acid was considered as an index for bacterial activity in the small intestine [56]. Dossin and Henroteaux [12] reported that hypoproteinemia and hypoalbuminemia were observed in IBD. Craven et al. [57] recorded hypoalbuminemia, hypoproteinemia, increased serum folate, and decreased serum cobalamin concentration in canine inflammatory bowel disease. Potoenjak et al. [38] and Brooks [58] observed hypoproteinemia, hypocholesterolemia, and hypocalcemia in lymphangiectasia. Marks [59] recorded that decreased serum cobalamin and increased folate concentration in SIBO affected dogs. Johnston [60] stated that indirect diagnosis of SIBO was made by estimation of deconjugated bile acid, serum cobalamin, and folate concentrations. Rutgers et al. [15] reported serum folate and cobalamin were only present in 5% of dogs with duodenal juice culture proven SIBO. Hall [61] suggested that serum folate and cobalamin concentrations cannot be used to diagnose SIBO because of the poor sensitivity, although a low serum cobalamin still has value as an indication to treat. Allenspach et al. [62] reported hypoalbuminemia and hypoglobulinemia are the important indicators of protein-losing enteropathy in dogs, and in such

case serum albumin concentration should be measured because hypoalbuminemia has been shown to be a negative prognostic indicator in dogs with chronic enteropathies.

#### **4.5 Fecal examination**

Berghoff and Steiner [63] reported chronic signs of intestinal disease should be evaluated for endoparasitic infestation before detail diagnostic examination to rule out hookworms (*Ancylostoma* spp., *Uncinaria* spp.), roundworms (*Toxocara* spp.), and whipworms (*Trichuris vulpis*). Broussard [49] stated that hookworm and *Ascaris* were diagnosed by standard fecal flotation method. Sokolow et al. [64] reported that *Giardia* could be diagnosed by the combination of fecal examination and centrifugal flotation.

Cystic stage of *Giardia* was diagnosed with zinc sulfate centrifugal or simple flotation technique and trophozoite stage by direct smear and detection of trophozoites and cysts in feces with FAT technique [46, 55]. Direct microscopic examination of fresh fecal samples suspended in saline could detect *Giardia* trophozoite [40, 59]. Fecal direct immunofluorescence assays were considered to be a golden standard method of diagnosis of *Giardia* infection in dogs, with a reported sensitivity and specificity of more than 90% each [65, 66]. Qualitative enzyme immunoassays (e.g., ProSpecT Giardia Microplate assay) and a SNAP test (SNAP Giardia Test) are also used for *Giardia* infection [41].

#### **4.6 Duodenoscopy**

Donaldson et al. [67] and Lamb [68] stated that gastroduodenoscopy was an important tool for examination of a dog with chronic vomiting and diarrhea and also suggested that visualization of duodenum, aspiration of duodenal contents, and microscopic examination of mucosal samples could be useful in diagnosis. Simpson [69] stated that indications for duodenoscopy were small bowel diarrhea, protein-losing enteropathies, chronic vomiting, and melena. Zoran [3] and Willard [70] reported that gastroduodenoscopy was not only valuable in visualization of mucosal irregularities and obtaining biopsies, cytologic samples, or fluids from duodenum but also might reveal anatomical distortions or displacements occurring in those regions.

Hinton et al. [8] reported that endoscopic examination was the diagnostic tool for gastroduodenal perforation. Moore [71] stated that most of the foreign bodies lodged in proximal duodenum could be removed by using endoscopy. Boston et al. [72, 73] reported that the endoscopy was commonly used to evaluate gastroduodenal ulceration and erosions induced by nonsteroidal anti-inflammatory drugs and corticosteroids. Endoscopic examination of the upper gastrointestinal tract had been used increasingly as a diagnostic and therapeutic tool in small animal medicine, particularly in the diagnosis of chronic gastrointestinal diseases and in understanding their pathophysiology [74].

#### *4.6.1 Endoscopic appearance of duodenum*

Peyer's patches (lymph node) are noticed as flattened areas on the lateral aspect of ascending duodenum [48]. Richter [42] reported that the normal duodenum was pink, smooth, and uniform with velvet-like texture. Normal duodenum appeared slightly grainy or roughened because of the presence of mucosal villi and was reddish pink to yellow if bile was present [3]. In descending duodenum, the major duodenal papilla were noticed approximately 4–5 cm from pylorus on medial aspect of duodenum, and minor duodenal papilla was located dorsal to the major papilla. Lymphoid follicle appeared as dished out area, often with white spots [70]. Bexfield [71] stated that the normal duodenum was more red in color than the stomach and had yellow tinge due to bile and also reported that the duodenal mucosa was more friable than that of the stomach and had a fine granular appearance due to the mass of intestinal villi.
