Abstract
Piglet coccidiosis due to Cystoisospora suis is a major cause of diarrhea and poor growth worldwide. It can effectively be controlled by application of toltrazuril (TZ), and oral formulations have been licensed for many years. Recently, the first parenteral formulation containing TZ in combination with iron (gleptoferron) was registered in the EU for the prevention of coccidiosis and iron deficiency anemia, conditions in suckling piglets requiring routine preventive measures. This study evaluated the absorption and distribution of TZ and its main metabolite, toltrazuril sulfone (TZ-SO2), in blood and intestinal tissues after single oral (20 mg/kg) or single intramuscular (45 mg/piglet) application of TZ. Fifty-six piglets were randomly allocated to the two treatment groups. Animals were sacrificed 1-, 5-, 13-, and 24-days post-treatment and TZ and TZ-SO2 levels were determined in blood, jejunal tissue, ileal tissue, and mixed jejunal and ileal content (IC) by high performance liquid chromatography (HPLC). Intramuscular application resulted in significantly higher and more sustained concentrations of both compounds in plasma, intestinal tissue, and IC. Higher concentrations after oral dosing were only observed one day after application of TZ in jejunum and IC. Toltrazuril was quickly metabolized to TZ-SO2 with maximum concentrations on day 13 for both applications. Remarkably, TZ and TZ-SO2 accumulated in the jejunum, the primary predilection site of C. suis, independently of the administration route, which is key to their antiparasitic effect.
Highlights
Porcine neonatal coccidiosis is a protozoal infection caused by the intestinal parasite Cystoisospora suis [1]
Cystoisosporosis is a major cause of diarrhea, poor growth performance resulting in significant economic losses in the pig breeding industry
While a number of different drug classes and compounds are effective and registered for the control of coccidiosis in other livestock [6], the only compound that can effectively suppress the endogenous development of C. suis is the triazinone toltrazuril (TZ), which is the only compound registered in the EU for metaphylactic use on affected farms [7]
Summary
Porcine neonatal coccidiosis is a protozoal infection caused by the intestinal parasite Cystoisospora suis (previously known as Isospora suis) [1]. Cystoisosporosis is a major cause of diarrhea, poor growth performance resulting in significant economic losses in the pig breeding industry. Piglets are infected by ingesting sporulated oocysts from contaminated farrowing crates. Upon ingestion of the sporulated oocyst, the infectious sporozoites are released and penetrate the epithelial cells of the ileum and jejunum. Reduced body weight gain contributes to the economic losses induced by the infection both in clinically affected and subclinically infected piglets [1]. While a number of different drug classes and compounds are effective and registered for the control of coccidiosis in other livestock [6], the only compound that can effectively suppress the endogenous development of C. suis is the triazinone toltrazuril (TZ), which is the only compound registered in the EU for metaphylactic use on affected farms [7]. Ponazuril is effective against C. suis [11] while diclazuril is not [12]
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