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)
Objective—To evaluate effects of dietary insoluble
fiber on control of glycemia in cats with naturally
acquired diabetes mellitus.
Design—Randomized controlled crossover trial.
Animals—16 cats with naturally acquired diabetes
Procedure—Cats were fed a diet high in insoluble
fiber (HF) containing 12% cellulose (dry-matter basis)
or a diet low in insoluble fiber (LF) for 24 weeks; they
were fed the other diet for the subsequent 24 weeks.
Caloric intake and insulin treatment were adjusted to
maintain stable body weight and control of glycemia,
respectively. Cats were allowed an adaption period of
6 weeks after initiation of a diet, after which control of
glycemia was evaluated at 6-week intervals for 18
weeks. Variables assessed included serum glucose
concentration measured during the preprandial state,
blood glycated hemoglobin concentration, serum glucose
concentration measured at 2-hour intervals for
12 hours beginning at the time of the morning insulin
injection, 12-hour mean serum glucose concentration,
and mean fluctuation in serum glucose concentration
from the 12-hour mean serum glucose concentration.
Results—Mean daily caloric intake, body weight, or
daily insulin dosage did not differ significantly
between cats when fed HF and LF diets. Mean
preprandial serum glucose concentration, most postprandial
serum glucose concentrations, and the 12-hour mean serum glucose concentration were significantly
lower when cats consumed the HF diet, compared
with values when cats consumed the LF diet.
Conclusions and Clinical Relevance—These results
support feeding a commercially available diet containing
approximately 12% insoluble fiber (dry-matter
basis) to cats with naturally acquired diabetes mellitus.
(J Am Vet Med Assoc 2000;216:1082–1088)