Coccidiosis: a radiological study of sulphaquinoxaline distribution in infected and uninfected chickens

摘要

Using scintillation counting and autoradiographical techniques, the whole‐body distribution in week‐old uninfected chickens of the anticoccidial agent sulphaquinoxaline (SQ) labelled with35S was established at various time intervals after a single oral dose either alone or following continuous in‐feed medication with unlabelled SQ, and after a single intravenous dose. The distribution was also established in chickens infected with the coccidiaEimeria acervulinaor E.tenella, after a single oral dose of radiolabelled SQ administered either alone or following continuous in‐feed medication with unlabelled SQ, as for uninfected chicks. In all uninfected chicks, SQ was rapidly absorbed from the gut and was distributed to all tissues. It appeared at high concentrations in the bile and kidneys 0.5 h after dosing. In chickens that had previously received unlabelled SQ in the diet, a radiolabelled dose maintained steadier tissue concentrations than the sharp rise and fall detected after a single oral dose. Intravenous dosing of uninfected chicks showed that SQ was secreted by the crop, gizzard and caecal epithelia into their lumina. Infection with E.acervulinaor E.tenellacoincided with an overall 3.5‐fold sustained increase of SQ concentration in chick tissues. An updated hypothesis including these new observations for the anticoccidial mode of action of SQ in chickens is