Dairy goat sulfadoxine depletion trial in milk and diagnostic accuracy of the Charm Rapid One Step Assay (ROSA) SULF test.

In Canada, currently no antibiotics are approved for use in lactating dairy goats. Trimethoprim sulfadoxine is indicated for the treatment of bacterial pneumonia, enteric and septicemic colibacillosis and salmonellosis, infectious pododermatitis, and septicemias. The aim of this study was to determine the trimethoprim sulfadoxine withdrawal time and evaluate the test accuracy of the Charm Rapid One Step Assay (ROSA) SULF test (Charm Sciences Inc.) at the individual goat level. The study was conducted on 20 visibly healthy Ontario dairy goats. They received trimethoprim sulfadoxine at a dose of 16 mg/kg i.m. once a day for 5 d as the commercially available preparation trimethoprim sulfadoxine (Borgal, Merck Animal Health). Residue levels were measured using liquid chromatography-tandem mass spectrometry and the Charm ROSA SULF. The withdrawal time was calculated using safe concentration linear regression. The determined milk withdrawal time was 60 h.