An increasing number of laboratory tests are available for diagnosis of gastrointestinal tract diseases in dogs and cats. Use of these tests can lead to more accurate and rapid diagnoses. This review discusses laboratory tests, both new and old, and the role they currently play in the evaluation of animals presented with gastrointestinal problems. A minimum database helps assess the severity of the disorder, detect extra-gastrointestinal causes of problems and assists in formulating diagnostic and therapeutic plans. Faecal examination remains one of the most important diagnostic procedures in the investigation of gastrointestinal problems.
Zinc sulphate faecal flotation is an excellent routine screening technique for helminth and protozoal
infections, including
giardiasis. Rectal cytology can assist in the diagnosis of large bowel disorders. Interpretation of faecal immunodiagnostic tests is hampered by insufficient knowledge of test sensitivities and specificities. Routine faecal cultures are not warranted and faecal occult blood tests are rarely indicated. Serum tests for gastric
inflammation are now under development. The serum
trypsin-like immunoreactivity test remains the gold standard technique for the diagnosis of
exocrine pancreatic insufficiency. Breath
hydrogen tests can be helpful in assessing the functional relevance of mild abnormalities in small-bowel biopsy specimens. Subnormal concentrations of serum
cobalamin appear to be more specific indicators of
gastrointestinal disease in cats than in dogs. Tests for small intestinal bacterial overgrowth remain controversial and assessment of gastrointestinal permeability has yet to prove its value in the diagnostic assessment of companion animals with gastrointestinal problems. Faecal alpha1-protease inhibitor shows promise for the diagnosis of
protein-losing enteropathy.