Lactulose test for the assessment of the intestinal permeability in ram after repeated indomethacin treatments

Increase of the intestinal permeability (IP) can occur for local pH reduction and lipopolysaccharides (LPS) release by bacteria; it can cause local and systemic inflammation with consequences for animal health. Changes of IP can be evaluated by a non-invasive test (never used in ruminant) based on oral dosage of lactulose -usually not fermented or absorbed- and its recovery in blood. This study aimed to induce intestinal damage (ID) in rams, by challenge of indomethacin, and to monitor it using the lactulose test (LACT) and blood indices. With a change-over design, 4 rams were subjected to 4 intramuscular injections (12 hours from each other) of saline (C) or indomethacin (T). Two hours after last injection, the rams were administered orally 30 g of lactulose. Blood samples were collected daily, for analysis of a metabolic profile and every 2 hours during the LACT for lactulose recovery in blood. Data were evaluated by ANOVA using the MIXED procedure (SAS Inst.). Three out of 4 rams in T showed -at different time- a blood lactulose peak, confirming clinical symptoms of diarrohea and blood in faeces. T rams also showed oxidative stress (e.g. reactive oxygen metabolite 17.3 vs 11.5 mg H2O2/100 mL in T and C respectively P<0.01 60 h post treatment), and inflammatory response: rise of positive acute phase proteins (e.g. haptoglobin 1.2 vs 0.1 g/L in T and C respectively, P<0.01 36 h post treatment) and drop of negative acute phase reactants (e.g. cholesterol, albumin and paraoxonase P<0.05). A good agreement between blood inflammatory indices and lactulose levels in blood was evident: T ram with low ID also showed almost an unchanged blood profile. We were not able to establish whether these results are the consequence of mucosa inflammation or LPS translocation in bloodstream or both. To clarify these hypotheses further experiments are recommended also in other ruminants, in particular dairy cow fed highly fermentable diets.