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- Author or Editor: Philip Walsh x
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Abstract
Objective—To determine the effects that routine histologic processing has on the dimensions of samples of normal skin of dogs and assess whether the inclusion of a muscle or fascial layer in such samples alters those effects.
Sample Population—Skin samples obtained from 6 medium-sized adult dogs with grossly normal skin.
Procedure—From each dog, skin samples (with or without underlying fascia or muscle) were obtained from 3 sites bilaterally (6 samples/dog) and processed routinely for histologic evaluation; their dimensions were measured at intervals during the experiment.
Results—As a result of processing, skin samples decreased in size (combined percentage change in length and width) and increased in thickness, compared with their original dimensions. Samples without fascia or muscle decreased in size by 21.1% to 32.0% and increased in thickness by 45.1% to 75.8%. The site of sample origin influenced processing-associated changes in sample size but did not affect the change in thickness. Decreases in dimensions did not vary with inclusion of fascia but did vary with inclusion of muscle. The change in thickness did not vary with inclusion of a layer of fascia or muscle.
Conclusions and Clinical Relevance—Processing of skin samples obtained from dogs for histologic evaluation can cause changes in sample dimensions; samples may decrease in length and width by as much as 32% and increase in thickness by 75.8%, compared with their original dimensions. The presence of muscle in canine skin samples can restrict the amount of shrinkage in length or width associated with processing. (Am J Vet Res 2005;66:500–505)
Abstract
OBJECTIVE To determine the effect of age on the pharmacokinetics and pharmacodynamics of flunixin meglumine following IV and transdermal administration to calves.
ANIMALS 8 healthy weaned Holstein bull calves.
PROCEDURES At 2 months of age, all calves received an injectable solution of flunixin (2.2 mg/kg, IV); then, after a 10-day washout period, calves received a topical formulation of flunixin (3.33 mg/kg, transdermally). Blood samples were collected at predetermined times before and for 48 and 72 hours, respectively, after IV and transdermal administration. At 8 months of age, the experimental protocol was repeated except calves received flunixin by the transdermal route first. Plasma flunixin concentrations were determined by liquid chromatography-tandem mass spectroscopy. For each administration route, pharmacokinetic parameters were determined by noncompartmental methods and compared between the 2 ages. Plasma prostaglandin (PG) E2 concentration was determined with an ELISA. The effect of age on the percentage change in PGE2 concentration was assessed with repeated-measures analysis. The half maximal inhibitory concentration of flunixin on PGE2 concentration was determined by nonlinear regression.
RESULTS Following IV administration, the mean half-life, area under the plasma concentration-time curve, and residence time were lower and the mean clearance was higher for calves at 8 months of age than at 2 months of age. Following transdermal administration, the mean maximum plasma drug concentration was lower and the mean absorption time and residence time were higher for calves at 8 months of age than at 2 months of age. The half maximal inhibitory concentration of flunixin on PGE2 concentration at 8 months of age was significantly higher than at 2 months of age. Age was not associated with the percentage change in PGE2 concentration following IV or transdermal flunixin administration.
CONCLUSIONS AND CLINICAL RELEVANCE In calves, the clearance of flunixin at 2 months of age was slower than that at 8 months of age following IV administration. Flunixin administration to calves may require age-related adjustments to the dose and dosing interval and an extended withdrawal interval.
