Bacterial overgrowth can be detected by breath hydrogen measurement before clinical manifestations in suckling lambs

Hydrogen breath test is a non-invasive and inexpensive method for estimation of small bowel transit time, detection of excess bacteria in the small intestine and demonstration of maldigestion or malabsorption. Until now, little has been known about breath hydrogen excretion in lambs. The aim of our study was to assess the patterns of breath hydrogen excretion in lambs before and after feeding ewe’s milk, and to evaluate pathological and/or physiological alterations in the lambs’ gastrointestinal function. We assumed that intestinal disorders may influence the breath hydrogen concentrations, which could be detected early in the subclinical stage. A total of 52 healthy blackheaded Dorper lambs were included in the study. Breath hydrogen was measured after overnight fasting and at 30, 60 and 90 min after the start of feeding. There was a 2-week follow-up period after the measurements to assess the gastrointestinal health of lambs. During the follow-up period, clinical signs of diarrhoea developed in 6 lambs. Based on our results in healthy lambs, the median concentration of baseline breath hydrogen was 1.00 parts per million (minimum: 0.00, maximum: 2.00). We observed a significant elevation in breath hydrogen concentrations 60 min after feeding (P = 0.004), whereas the values detected 30 min after feeding were similar to the baseline values. Regarding the lambs in which clinical signs of diarrhoea developed, we revealed significantly higher baseline breath hydrogen concentrations compared to those which remained healthy (P < 0.001). Our observations underline that hydrogen breath test may be a useful tool for indicating potential bacterial overgrowth before any clinical signs of diarrhoea. Diagnosis, diarrhoea, hydrogen breath test Hydrogen breath test is a simple, non-invasive and inexpensive method for estimating small bowel transit time, detecting the existence of excess bacteria in the small intestine, and demonstrating carbohydrate maldigestion or malabsorption (Washabau et al. 1986; Misselwitz et al. 2013). The rationale of hydrogen breath tests is based on the concept that parts of the gas produced by colonic bacteria fermentation diffuse into the blood and are rapidly excreted by breath (D’Angelo et al. 2013). One of the exhaled substances is hydrogen, which can be measured relatively easily with the help of handy breath test devices. Hydrogen in the exhaled air was only generated during anaerobic metabolism, consequently, the hydrogen measured in the exhaled breath sheds light on the quantity and metabolic activity of anaerobic bacteria in the gut (Mastropaolo and Rees 1987). Unabsorbed dietary carbohydrates that reach the colon are metabolized by bacteria to hydrogen, methane, and short chain fatty acids (Gasbarrini et al. 2009). Hydrogen measurement is routinely used in human medicine to investigate the gastrointestinal function. This method has been applied successfully to the clinical investigation of small intestinal carbohydrate malabsorption (Levitt and Donaldson 1970; Bond and Levitt 1976), small intestinal bacterial overgrowth (Metz et al. 1976) and for the assessment of mouth-to-caecum transit time (Bond et al. 1975). The development of portable breath