Pleuromutilin (tiamulin/valnemulin) therapy in swine dysentery: does it shorten clinical disease and shedding vs no antimicrobial treatment? — MAYBE (weak evidence)

MAYBE (weak evidence): The clinical-trial literature comparing pleuromutilin therapy with NO antimicrobial treatment in swine dysentery is old, small in its reporting, and — in the abstracts fetched at drafting — almost entirely without numbers, so no duration of disease or shedding in days, and no cure-rate percentage, can be stated for treated vs untreated pigs from the carded records. Pickles 1982 (PMID: 7090152) compared tiamulin in drinking water (0.0045% for 5 days, or 0.006% for 3 days) with tylosin positive controls and with UNTREATED controls across six farm studies of naturally occurring dysentery, assessing general appearance, diarrhoea and dehydration, daily gain and feed conversion, faecal Treponema hyodysenteriae (now Brachyspira hyodysenteriae) presence and mortality, and concluded on statistical analysis that tiamulin was an efficacious therapeutic regimen — but the abstract reports no rate, mean or day count for any group. Taylor 1980 (PMID: 7434520), in experimental dysentery, found tiamulin in water effective at 22.5, 45 and 60 ppm for 3 and 5 days, with only 60 ppm for 3 and 5 days completely preventing relapse and eliminating T. hyodysenteriae. Olson 1986 (PMID: 3721965) found diarrhoea receded on tiamulin 45 or 60 mg/L but recurred 2-10 days (average 4.1 days) after withdrawal, that 22.5 mg/L did not markedly reduce diarrhoea, and that tylosin 66 mg/L was not effective — a within-treatment comparison with no untreated arm described in the abstract. The one modern controlled record, Sperling 2014 (PMID: 24287025), experimentally challenged pigs with B. hyodysenteriae strain B204 and, once signs and shedding developed, divided them into zinc chelate, valnemulin 75 ppm in feed, both, and an untreated control group, and reports that valnemulin demonstrated a therapeutic effect in pigs with serious dysentery while zinc chelate did not — again with no clinical-duration or shedding figures in the abstract. Design class (c): randomisation is not established — no carded record's abstract states randomised allocation or blinding for the treated-vs-untreated comparison. The stamp is MAYBE (weak evidence), not POSSIBLE, because every carded comparison rests on author conclusions and significance statements without a single absolute clinical or shedding figure in the fetched records, the untreated-control evidence is from 1980-1982 farm studies plus one small 2014 challenge study, and the extensive modern pleuromutilin literature is in vitro susceptibility work (MICs), which cannot carry a clinical claim. Tier C call, recorded explicitly on the pack's face: mortality was one of the assessment parameters in Pickles 1982, but its abstract reports no mortality figures and claims no mortality benefit, so this is not a mortality/fetal-loss/survival-primary benefit claim and Tier C is NOT engaged. One-home cross-points: shelf #926 (toltrazuril in piglet coccidiosis) is a different disease and shares no record; the mycoplasmal-pneumonia tiamulin trial (PMID: 14516155) is a different disease and is not carded here. Drafted Nov 10, 2026 (VetMed build, topic #923); figures from the abstracts, fetched and verified at drafting.