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- Author or Editor: Michael A. Payne x
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Objective—To determine efficacy of treatment with a combination febantel-praziquantel-pyrantel product, with or without vaccination with a commercial Giardia vaccine, in dogs with naturally occurring giardiasis.
Animals—16 Beagles naturally infected with Giardia duodenalis.
Procedures—During phase 1, 6 dogs were treated with the parasiticide for 3 days (4 were also vaccinated). Four weeks later, all 6 dogs were treated with the parasiticide again for 5 days and were bathed and moved to clean cages after the last treatment (phase 2). Nine dogs were treated with the parasiticide for 3 (n = 4) or 5 (5) days and bathed and moved to clean cages after the last treatment (phase 3). Fecal samples were collected twice weekly for 24 days after treatment and tested for cysts with a quantitative zinc sulfate flotation technique and for Giardia antigen with an immunoassay.
Results—Dogs in phase 1 were all shedding cysts again by day 24. In phase 2, only 1 dog shed cysts after treatment, and shedding was transient (day 17). In phase 3, neither cysts nor antigen was detected in fecal samples from 2 of 4 dogs treated for 3 days and 4 of 5 dogs treated for 5 days. In 18 of 57 (31.6%) fecal samples, cysts were seen, but results of the immunoassay were negative.
Conclusions and Clinical Relevance—Results suggest that when a combination febantel-praziquantelpyrantel product is used to treat dogs with giardiasis, bathing and changing the environment after treatment may be more important in preventing recurrence than duration of treatment. (J Am Vet Med Assoc 2002;220:330–333)
Objective—To compare the results of regulatory screening and confirmation assays with those of highperformance liquid chromatography (HPLC) in the detection of ceftiofur metabolites in the tissues of culled dairy cattle.
Animals—17 lactating Holstein dairy cows.
Procedure—Daily IM injections of ceftiofur sodium were administered at a dose of 2.2 mg of ceftiofur equivalents/kg (n = 6) or 1.0 mg of ceftiofur equivalents/kg (10) for 5 days. Following withdrawal times of 12 hours (high-dose ceftiofur) and either 5 or 10 days (low-dose ceftiofur), cows were slaughtered and liver, kidney, and diaphragmatic muscle specimens were harvested and analyzed by HPLC and standard regulatory methods that included the following assays: the swab test on premises, the fast antimicrobial screen test, the calf antibiotic and sulfa test, and the 7-plate bioassay confirmation test.
Results—In all tissue specimens, residues of ceftiofur and desfuroylceftiofur-related metabolites, as measured by HPLC, were less than regulatory tolerance, as defined by the FDA. False-positive screening assay results were more likely for tissue specimens that had been frozen for shipment to a federal laboratory, compared with fresh tissue specimens that were assayed at the slaughter establishment (23% vs 3% false-positive results, respectively).
Conclusions and Clinical Relevance—The observation that fresh tissues had negative results on screening assays, whereas subsets of the same tissue specimens had false-positive results on screening assays following freezing, suggests that freezing and thawing interferes with microbial inhibition-based regulatory screening assays. (Am J Vet Res 2004;65:1730–1733)