Vet360, December 2016 | Page 15

These tests can help narrow down your differential veterinary diagnoses for chronic enteropathies .
GASTRO-ENTEROLOGY
Article reprinted with the permission of Advanstar . The article was originally printed in VETERINARY MEDICINE December 2014 . VETERINARY MEDICINE is a copyrighted publication of Advanstar . Communications inc . All rights reserved .

Practical Gastroinstestinal

Function Testing

Albert E . Jergens , DVM , PhD , DACVIM Department of Veterinary Clinical Sciences Iowa State University
These tests can help narrow down your differential veterinary diagnoses for chronic enteropathies .
Chronic enteropathies are common in dogs and cats and include adverse reactions to food , idiopathic inflammatory bowel disease ( IBD ), and antibiotic-responsive diarrhoea . While definitive diagnosis often requires collecting mucosal biopsy samples for histopathologic evaluation , noninvasive laboratory tests are useful in diagnosing these disorders and monitoring treatment .
Tests for small intestinal function and disease Cobalamin The physiologic mechanism of cobalamin ( vitamin B12 ) is complex and requires a functioning digestive system . Major disorders that interfere with cobalamin uptake include exocrine pancreatic insufficiency , distal or diffuse small intestinal disease , and excessive bacterial utilisation of cobalamin associated with bacterial dysbiosis .
Hypocobalaminaemia is most often seen with long-standing and severe intestinal disease ( IBD , lymphoma , or fungal enteritis ) affecting the small intestine . Measuring serum cobalamin concentrations in animals with chronic enteropathies is important since failure to recognise this deficiency may result in delay of clinical recovery .
Importantly , low serum cobalamin concentrations have been shown to be a risk factor for negative outcome in dogs with chronic enteropathies , including IBD and protein-losing enteropathy ( PLE ). If low concentrations are detected , appropriate dosages of cyanocobalamin are typically administered subcutaneously once a week , with serum concentrations reassessed at four- to six-week intervals .
Folate This water-soluble vitamin ( vitamin B9 ) is abundant in canine and feline diets , making nutritional deficiencies unlikely . Folate concentrations are typically measured in concert with cobalamin and may provide information indicative of small intestinal dysbiosis or proximal small intestinal mucosal disease . Note that serum folate concentrations may be influenced by bacterial production of folate and are therefore a less sensitive indicator of small intestinal disease than cobalamin .
Citrulline This amino acid is synthesised predominantly by intestinal enterocytes . Citrulline has been shown to be a marker of functional enterocyte metabolic mass , and preliminary studies have shown plasma citrulline concentrations are significantly decreased in dogs with parvovirus enteritis . Thus , citrulline might serve as a potential marker of spontaneous and acute intestinal dysfunction . However , additional clinical trials evaluating this marker are warranted .
Evaluation of intestinal protein loss PLEs are a heterogeneous group of disorders characterised by enteric loss of plasma proteins . Common causes of PLE include inflammatory enteropathies , infectious enteritis , lymphangiectasia , intestinal neoplasia , and marked microbial imbalances . Most animals exhibit the classic clinical signs of emaciation and weight loss , and panhypoproteinemia is often found on laboratory evaluation .
It is important to first rule out other causes of hypoalbuminemia due to glomerular injury and hepatic failure or insufficiency . Definitive diagnosis of PLE requires the collection and histopathologic assessment of mucosal biopsy samples .
Faecal A1-PI An ELISA assay for the measurement of fecal alpha 1-proteinase inhibitor ( A1-PI ) has been validated in dogs and may be used to assess protein loss in the gastrointestinal ( GI ) tract . Due to the cumbersome criteria for collecting multiple fecal samples , the lab-
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