Division of patients according to the findings on initial evaluation

Patients are divided into two groups according to the case history findings, physical examination, and laboratory results (Figure 2.3). The first group includes patients that show clini­cal abnormalities in addition to the diarrhea (Group A), while the second group (Group B) does not show any obvious ab­normalities except for diarrhea.

2.3.3.1 Patients with obvious abnormalities (A)

Systemic disorders with secondary diarrhea (A1a)

Several systemic diseases lead to secondary chronic diarrhea. Hepatic failure can lead to chronic diarrhea, and abnormally high serum ALT or ALP activities, bilirubin concentrations, or decreased serum albumin, cholesterol, or urea nitrogen con­centrations should prompt a further workup. Renal failure can also lead to chronic diarrhea and elevations in serum creati­nine and urea nitrogen concentrations may indicate the pres­ence of renal failure. Hypoadrenocorticism in dogs can be as­sociated with hyperkalemia and hyponatremia, but some patients do not have electrolyte abnormalities. The lack of a stress leukogram in a dog with chronic diarrhea should raise a suspicion of possible hypoadrenocorticism and should prompt the clinician to perform an ACTH stimulation test. Other sys­temic conditions, such as hypothyroidism in dogs and hyper­thyroidism in cats can also lead to chronic diarrhea.

Exocrine pancreatic insufficiency (A1b)

Exocrine pancreatic insufficiency (EPI; see 8) is diagnosed by a severely decreased serum trypsin-like immunoreactivity (TLI) concentration (cTLI ≤2.5 μg∕L in dogs and fTLI ≤8 μg∕L in cats) in association with signs of maldigestion (i. e. polyphagia, weight loss, and/or yellowish loose feces). If the serum TLI concentration is in the questionable range (be­tween 2.5-5.0 μg∕L in dogs and between 8-12 μg∕L in cats), the measurement should be repeated after approximately 1 month.Repeatedly low serum cTLI concentrations (prednisone at 1-2 mg/kg, twice daily. If side effects (e.g., se­vere polyuria /polydipsia, panting, or lethargy) are intolerable, other corticosteroids, such as budesonide, a locally active cor­ticosteroid, have been recommended.

Pathogenic bacteria (B6)

Fecal culture, especially for Salmonella spp., Campylobacter spp., and Yersinia spp. is particularly indicated in animals that de­velop chronic diarrhea after being kenneled with other dogs.

2.3.4