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  • Author or Editor: S. Mark Hall x
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The effect of trimethoprim/sulfamethoxazole (t/smx, 30 mg/kg, po, q 12 h for 6 weeks) on thyroid function was evaluated in 21 dogs with pyoderma and normal baseline serum thyroxine concentrations. The population mean serum thyroxine concentration, but not the population mean serum triiodothyronine concentration, was significantly decreased at the end of treatment. After 6 weeks of treatment, the response in 3 dogs to thyrotropin administration was substantially reduced. Radionuclide thyroid imaging of 2 dogs after t/smx treatment revealed higher-than-normal thyroid technetium 99m pertechnetate uptake, suggestive of an interference with iodide metabolism.

Use of t/smx may cause hypothyroidism, and inadequate thyroid function may be incorrectly diagnosed in dogs treated with this antimicrobial.

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in Journal of the American Veterinary Medical Association


Objective—To determine the suitability and estimate the sensitivity of an immunohistochemical (IHC) test for disease-associated prion protein (PrPSc) in biopsy specimens of rectoanal mucosa–associated lymphoid tissue (RAMALT) for diagnosis of scrapie in sheep.

Animals—762 sheep at high risk for having scrapie and indemnified by the National Scrapie Eradication Program.

Procedures—The IHC test for PrPSc was applied to 2 RAMALT and 2 third-eyelid biopsy specimens and a postmortem RAMALT specimen from each sheep. Results were compared with those of a reference test in which results for tissues from obex and retropharyngeal lymph nodes, tonsil, or both were considered in parallel.

Results—The reference test identified 139 sheep as having scrapie. Biopsy-related complications occurred in 3 sheep. Sensitivity of the IHC test in RAMALT ranged from 85.3% to 89.4%, depending on the anatomic location from which RAMALT was obtained. Results for the test applied to 1 RAMALT specimen were similar to results interpreted in parallel for 2 third-eyelid specimens (sensitivity, 87.0%). The proportion of inconclusive test results attributable to insufficient lymphoid follicles in biopsy specimens was lower when considering results for 2 RAMALT specimens in parallel (10.1%) than when considering results for 2 third-eyelid specimens in parallel (23.7%). Specimens of RAMALT that were inappropriately collected from an area caudal to the rectoanal interface yielded a high proportion of inconclusive results (33.3% to 50.0%).

Conclusions and Clinical Relevance—The IHC test for PrPSc in RAMALT was an effective means of detecting subclinical scrapie in live, high-risk sheep.

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in American Journal of Veterinary Research