Changes

Traditionally, the gold standard direct test for diagnosing ARD has been '''culture of duodenal juice''' collected during endoscopy.  Unfortunately, this is an expensive test and it is rarely available.  However the major complaint to be made about duodenal juice culture is that it is currently not possible to define a normal control result in dogs <ref name="two">nothing</ref><ref name="three">German AJ, Day MJ, Ruaux CG, Steiner JM, Williams DA, Hall EJ. '''Comparison of direct and indirect tests for small intestinal bacterial overgrowth and antibiotic-responsive diarrhea in dogs.''' ''J Vet Intern Med. 2003 Jan-Feb;17(1):33-43.''</ref> and cats.  Traditionally, bacterial numbers greater than 10e5 CFU/ml juice with anaerobes greater than 10e4 CFU/ml were considered to be diagnostic of ARD.

Traditionally, the gold standard direct test for diagnosing ARD has been '''culture of duodenal juice''' collected during endoscopy.  Unfortunately, this is an expensive test and it is rarely available.  However the major complaint to be made about duodenal juice culture is that it is currently not possible to define a normal control result in dogs <ref name="two">nothing</ref><ref name="three">German AJ, Day MJ, Ruaux CG, Steiner JM, Williams DA, Hall EJ. '''Comparison of direct and indirect tests for small intestinal bacterial overgrowth and antibiotic-responsive diarrhea in dogs.''' ''J Vet Intern Med. 2003 Jan-Feb;17(1):33-43.''</ref> and cats.  Traditionally, bacterial numbers greater than 10e5 CFU/ml juice with anaerobes greater than 10e4 CFU/ml were considered to be diagnostic of ARD.

Indirect tests such as serum '''folate''' and '''cobalamin''' concentrations have been used to give an indication of the bacterial population in small intestine.  Some species of bacteria may increase the level of serum folate concentration or decrease serum cobalamin concentration, or both. The sensitivity of these tests (~65%) is low and therefore their use in the diagnosis of ARD is questionable <ref name="three">nothing</ref>.  Folate is absorbed in the jejunum and severe jejunal disease (such as [[Inflammatory Bowel Disease|inflammatory bowel disease]] may decrease serum folate concentration.  Cobalamin associates with '''Intrinsic Factor''' produced in the stomach and pancreas of dogs and the pancreas of cats and this complex is absorbed in the ileum.  Pancreatic disease may reduce the production of intrinsic factor and ileal disease may reduce the absorption of the complex.  Cobalamin deficiency may cause villous atrophy and, in severe cases, non-regenerative macrocytic anaemia due to a failure of red blood cell nuclear maturation (the equivalent of pernicious anaemia in humans).  An documented deficiency in cobalamin should therefore be treated with B vitamin injections.

Indirect tests such as serum '''folate''' and '''cobalamin''' concentrations have been used to give an indication of the bacterial population in small intestine.  Some species of bacteria may increase the level of serum folate concentration or decrease serum cobalamin concentration, or both. The sensitivity of these tests (~65%) is low and therefore their use in the diagnosis of ARD is questionable <ref name="three">nothing</ref>.  Folate is absorbed in the jejunum and severe jejunal disease (such as [[Inflammatory Bowel Disease|inflammatory bowel disease]]) may decrease serum folate concentration.  Cobalamin associates with '''Intrinsic Factor''' produced in the stomach and pancreas of dogs and the pancreas of cats and this complex is absorbed in the ileum.  Pancreatic disease may reduce the production of intrinsic factor and ileal disease may reduce the absorption of the complex.  Cobalamin deficiency may cause villous atrophy and, in severe cases, non-regenerative macrocytic anaemia due to a failure of red blood cell nuclear maturation (the equivalent of pernicious anaemia in humans).  An documented deficiency in cobalamin should therefore be treated with B vitamin injections.

The concentration of serum '''unconjugated bile acids''' is increased in ~15% of animals with ARD.  Intestinal bacteria deconjugate bile acids and these are then reabsorbed in the ileum to complete the enterohepatic circulation.  Unconjugated bile acids cannot be so easily removed from the portal blood by the liver as conjugated acids and they therefore reach high blood concentrations.  Unconjugated bile acids may also be elevated with other GI diseases and even in animals that have no apparent signs of GI disease <ref name="three">nothing</ref>.

The concentration of serum '''unconjugated bile acids''' is increased in ~15% of animals with ARD.  Intestinal bacteria deconjugate bile acids and these are then reabsorbed in the ileum to complete the enterohepatic circulation.  Unconjugated bile acids cannot be so easily removed from the portal blood by the liver as conjugated acids and they therefore reach high blood concentrations.  Unconjugated bile acids may also be elevated with other GI diseases and even in animals that have no apparent signs of GI disease <ref name="three">nothing</ref>.