Abstract
Simple SummaryThe antibiotic-responsive enteropathy is a common canine chronic disorder for which tylosin represents an effective widely used therapeutic option, although its mechanism of action, beyond the well-known antibacterial activity, is still unclear. Given the beneficial role of prebiotic substrates for gut health, positive outcomes deriving from the association of tylosin with some prebiotic oligosaccharides might be supposed. The present study investigated in vitro the effects of tylosin, alone or supplemented with fructooligosaccharides, galactooligosaccharides, or xylooligosaccharides, on the composition and activity of the fecal microbiota of healthy dogs. It was partially confirmed that the antibacterial effect of tylosin, given the reduction of some microbial populations and metabolites, e.g., volatile fatty acids. Interestingly, the association of tylosin with prebiotics revealed counteracting effects on some undesirable changes exerted by tylosin, e.g., the reduction of bacteria generally considered beneficial such as lactobacilli and Clostridium cluster XIVa as well as volatile fatty acids, i.e., microbial fermentative end-products that are recognized as essential for enterocytes homeostasis.The present study investigated the in vitro effects of tylosin (TYL), alone or associated with prebiotics (PRE), on selected canine fecal parameters. Eight treatments were set up: control diet with no addition of substrates; TYL; Fructooligosaccharides (FOS); Galactooligosaccharides (GOS); Xylooligosaccharides (XOS); TYL + FOS; TYL + GOS; TYL + XOS. The flasks (five for treatment), containing a canine fecal suspension (prepared with the feces of healthy adult dogs) and the residue of an in vitro digested dry dog food, were incubated in an anaerobic chamber at 39 °C. TYL and PRE were added at a concentration of 0.2 and 1 g/L, respectively. Samples were collected after 6 and 24 h for analyses. PRE decreased pH values, iso-butyrate, and iso-valerate throughout the incubation; increased lactobacilli, cadaverine, and, tendentiously, total volatile fatty acids after 6 h; increased n-butyrate, putrescine, spermidine, and reduced spermine and E. coli after 24 h. TYL resulted in lower total volatile fatty acids and lactobacilli and higher Clostridium cluster I after 6 h and higher pH values, spermidine, and E. coli throughout the study. When associated with TYL, PRE counteracted some undesirable effects of the antibiotic such as the decrease of lactobacilli and Clostridium cluster XIVa at both 6 and 24 h. In the present study, TYL exhibited inhibitory effects on canine fecal microbiota partially counteracted by PRE supplementation.
Highlights
Among the chronic gastrointestinal disorders in the dog, the antibiotic responsive enteropathy (ARE) represents a very common pathology, which is typically manifested through chronic diarrhea.The diagnosis is “empiric”, since it is traditionally based on the remission of the clinical signs within a few days from the beginning of antibiotic therapy, usually after an ineffective nutritional intervention aimed to exclude dietary adverse food reactions [1]
The use of antibiotics is not resolutive for the treatment of ARE, since diarrhea commonly reappears within a few months after the suspension of the therapy; most of the dogs need lifelong treatments to achieve the control of the disease [2,3,4]
The undigested fraction was dried at 65 ◦ C until a constant dry weight was obtained (18.5 g of undigested residue were obtained from 100 g of food dry matter [DM]) and its chemical composition per kg was the following: crude protein (CP) 173 g, ether extract (EE) 24.3 g, starch 38.7 g, ash 146 g, and crude fiber (CF) 99.4 g
Summary
Among the chronic gastrointestinal disorders in the dog, the antibiotic responsive enteropathy (ARE) represents a very common pathology, which is typically manifested through chronic diarrhea.The diagnosis is “empiric”, since it is traditionally based on the remission of the clinical signs within a few days from the beginning of antibiotic therapy, usually after an ineffective nutritional intervention aimed to exclude dietary adverse food reactions [1]. Among the chronic gastrointestinal disorders in the dog, the antibiotic responsive enteropathy (ARE) represents a very common pathology, which is typically manifested through chronic diarrhea. The use of antibiotics is not resolutive for the treatment of ARE, since diarrhea commonly reappears within a few months after the suspension of the therapy; most of the dogs need lifelong treatments to achieve the control of the disease [2,3,4]. In this regard, the term “tylosin responsive diarrhea”. A macrolide antibiotic registered exclusively for veterinary use, exerts its antibacterial action by binding to 23S rRNA of the bacterial ribosomal 50S subunit, preventing protein synthesis predominantly in gram-positive bacteria [5]. Anti-inflammatory effects through the modulation of the synthesis of several mediators and cytokines involved in the inflammatory process have been proposed for this antibiotic [6]
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