Procedure—Soy isoflavone content of each food was
determined by use of acid-methanol hydrolysis and
high-pressure liquid chromatography with ultraviolet
absorbance detection. Isoflavones were identified
and quantified by reference to authentic standards.
Results—Genistein and daidzein were the major soy
isoflavones identified in 24 of 42 foods, with concentrations
ranging from 1 to 163 µg/g of food. Foods
labeled as containing soybean solids (16/42) had
isoflavone concentrations > 11 µg/g. More dry (13/14)
and semimoist (6/6) foods contained isoflavones than
moist foods (5/22). Isoflavone content and food cost
were negatively correlated for dry and semimoist
foods but not for moist foods. Total amount of
isoflavone consumed by cats fed these soy-containing
foods as a sole maintenance diet was estimated
to be between 0.6 and 4.5 mg/kg of body weight/d,
which is comparable to concentrations in humans that
result in a measurable although modest effect on
serum concentrations of steroid and thyroid hormones.
Conclusions and Clinical Relevance—Genistein and
daidzein are common constituents of commercial cat
foods. Predictors of isoflavone content included ingredient
labeling, food type, and food cost. Soy
isoflavones in some commercial cat foods were
detected in amounts predicted to have a biological
effect. (Am J Vet Res 2002;63:181–185)
Objective—To identify and determine the concentrations
of phytoestrogens in commercial dog foods.
Sample Population—24 commercial dog foods,
including 12 moist or dry extruded commercial dog
foods that contained soybeans or soybean fractions
and 12 foods without any soybean–related ingredients
listed on the label.
Procedure—Foods were analyzed for phytoestrogen
content, including 4 isoflavones (genistein, glycitein,
daidzein, and biochanin A), 1 coumestan (coumestrol),
and 2 lignans (secoisolariciresinol and matairesinol) by
use of acid-methanol hydrolysis and high-pressure liquid
chromatography with UV-absorbance detection.
Phytoestrogens were identified and quantified by reference
to authentic standards.
Results—Isoflavones, coumestans, and lignans were
undetectable in diets that did not list soybean–related
ingredients on the label. Only 1 of the 12 diets that
included soybean or soybean fractions had undetectable
concentrations of phytoestrogens and that
product contained soy fiber. The major phytoestrogens
were the isoflavones daidzein (24 to 615 µg/g of
dry matter) and genistein (4 to 238 µg/g of dry matter).
Conclusions and Clinical Relevance—Soybean and
soybean fractions are commonly used ingredients in
commercial dog foods. Dietary intake of phytoestrogens
may have both beneficial and deleterious health
effects. Our results indicated that certain commercial
dog foods contain phytoestrogens in amounts that
could have biological effects when ingested longterm.
( Am J Vet Res 2004;65:592–596)
Objective—To determine whether oral administration of metoclopramide or a commercially available powdered whole grapefruit (PWG) nutraceutical in combination with cyclosporine enhances systemic availability of cyclosporine in dogs.
Sample—8 healthy mixed-breed dogs in part 1 and 6 of these 8 dogs in part 2.
Procedures—Cyclosporine pharmacokinetics were determined over the course of 24 hours after oral administration of cyclosporine (5 mg/kg) alone, cyclosporine with metoclopramide (0.3 to 0.5 mg/kg), cyclosporine with 2 g of PWG, or cyclosporine combined with both metoclopramide and 2 g of PWG by use of a Latin square crossover study with a 14-day washout period between treatments. Sixty days later, 6 of the 8 dogs were given 10 g of PWG followed by cyclosporine, and pharmacokinetic parameters were compared with those previously obtained after administration of cyclosporine alone.
Results—Although metoclopramide or coadministration of metoclopramide and 2 g of PWG had no effect on the pharmacokinetic parameters of cyclosporine, compared with results for cyclosporine alone, the higher (10-g) dose of PWG resulted in 29% faster mean time to maximal plasma cyclosporine concentration, 54% larger area under the curve, and 38% lower apparent oral clearance.
Conclusions and Clinical Relevance—Adjustment of the cyclosporine dose may not be needed when metoclopramide is coadministered orally to prevent common adverse effects of cyclosporine. Powdered whole grapefruit has the potential to reduce the required orally administered dose of cyclosporine but only when PWG is used in an amount (at least 10 g) that is currently not cost-effective.
To determine the pharmacokinetics of terbinafine in little brown myotis (Myotis lucifugus) infected with Pseudogymnoascus destructans.
123 bats from a P destructans–infected hibernation site in Virginia.
3 bats were euthanized and necropsied to confirm the presence of P destructans within the population. The remaining 120 bats were systematically assigned to 6 groups (20 bats/group). Bats in each of 3 groups received 6, 20, or 60 mg of terbinafine/kg, SC, once daily for 10 days. Bats in another group received 200 mg of terbinafine/kg, SC, once daily for 5 days. Bats in 1 group received the terbinafine vehicle solution (0.1 mL/kg, SC, once daily for 10 days). Bats in the remaining group did not receive any treatment. Following the treatment period (days 1 through 10), bats were housed in a hibernation chamber and monitored daily until euthanasia on day 42, 75, or 109. Tissue specimens were collected from all bats as soon as possible after death or euthanasia to determine terbinafine concentration. Within each group and tissue type, terbinafine concentration data were pooled, and pharmacokinetic parameters were calculated by noncompartmental methods.
Adverse neurologic effects and a high mortality rate before day 10 were observed in bats that received the highest terbinafine dose (200 mg/kg) but not those that received lower doses. Presumed therapeutic terbinafine concentrations (≥ 2 μg/g) were maintained in skin and wing for at least 30 and 6 days in bats that received the 60 and 20 mg/kg doses, respectively, but were not achieved in most bats that received the 6 mg/kg dose. Tissue terminal half-life ranged from 14 to 22 days. Terbinafine concentration in hair was positively correlated with that in skin and wing.
CONCLUSIONS AND CLINICAL RELEVANCE
Results indicated terbinafine doses > 6 but < 200 mg/kg should be further evaluated for the treatment of P destructans–infected bats. Collection of serial hair specimens may represent a noninvasive method for monitoring terbinafine concentration in treated bats.
Objective—To compare effects of short-term administration
of a soy diet with those of a soy-free diet on
serum thyroid hormone concentrations in healthy
Animals—18 healthy adult cats.
Procedure—Cats were randomly assigned to receive
either a soy or soy-free diet for 3 months each in a
crossover design. Assays included CBC, serum biochemical
profile, thyroid hormone analysis, and measurement
of urinary isoflavone concentrations.
Results—Genistein, a major soy isoflavone, was
identified in the urine of 10 of 18 cats prior to dietary
intervention. Compared with the soy-free diet, cats
that received the soy diet had significantly higher total
thyroxine (T4) and free T4 (fT4) concentrations, but
unchanged total triiodothyronine (T3) concentrations.
The T3/fT4 ratio was also significantly lower in cats
that received the soy diet. Although the magnitudes
of the increases were small (8% for T4 and 14% for
fT4), these changes resulted in an increased proportion
of cats (from 1/18 to 4/18) that had fT4 values
greater than the upper limit of the laboratory reference
range. There was no significant effect of diet on
any other measured parameter.
Conclusions and Clinical Relevance—Short-term
administration of dietary soy has a measurable
although modest effect on thyroid hormone homeostasis
in cats. Increase in T4 concentration relative to
T3 concentration may result from inhibition of 5'-iodothyronine deiodinase or enhanced T3 clearance.
Soy is a common dietary component that increases
serum T4 concentration in cats. ( Am J Vet Res 2004;
Objective—To compare pharmacokinetics after IV, IM, and oral administration of a single dose of meloxicam to Hispaniolan Amazon parrots (Amazona ventralis).
Animals—11 healthy parrots.
Procedures—Cohorts of 8 of the 11 birds comprised 3 experimental groups for a crossover study. Pharmacokinetics were determined from plasma concentrations measured via high-performance liquid chromatography after IV, IM, and oral administration of meloxicam at a dose of 1 mg/kg.
Results—Initial mean ± SD plasma concentration of 17.3 ± 9.0 μg/mL was measured 5 minutes after IV administration, whereas peak mean concentration was 9.3 ± 1.8 μg/mL 15 minutes after IM administration. At 12 hours after administration, mean plasma concentrations for IV (3.7 ± 2.5 μg/mL) and IM (3.5 ± 2.2 μg/mL) administration were similar. Peak mean plasma concentration (3.5 ± 1.2 μg/mL) was detected 6 hours after oral administration. Absolute systemic bioavailability of meloxicam after IM administration was 100% but was lower after oral administration (range, 49% to 75%). Elimination half-lives after IV, IM, and oral administration were similar (15.9 ± 4.4 hours, 15.1 ± 7.7 hours, and 15.8 ± 8.6 hours, respectively).
Conclusions and Clinical Relevance—Pharmacokinetic data may provide useful information for use of meloxicam in Hispaniolan Amazon parrots. A mean plasma concentration of 3.5 μg/mL would be expected to provide analgesia in Hispaniolan Amazon parrots; however, individual variation may result in some birds having low plasma meloxicam concentrations after IV, IM, or oral administration. After oral administration, meloxicam concentration slowly reached the target plasma concentration, but that concentration was not sustained in most birds.
Objective—To determine whether rocuronium, a
reversible neuromuscular blocking agent, would provide
safe, short-term immobilization to facilitate endotracheal
intubation in turtles.
Animals—30 healthy adult Gulf Coast box turtles.
Procedure—Turtles were given rocuronium, and
responses were recorded every 3 minutes. Times
to onset of effects, intubation, and recovery were
recorded and analyzed for associations with dose
and patient characteristics to determine an optimal
dose range. Neostigmine and glycopyrrolate were
given to augment recovery from neuromuscular
Results—Rocuronium administered at a dose of
0.25 to 0.5 mg/kg (0.11 to 0.23 mg/lb), IM, permitted
intubation; lower doses were not effective.
Mean ± SD time to loss of the palpebral reflex was
6.4 ± 4.0 minutes, and mean time to intubation was
9.2 ± 6.4 minutes. Mean time to return of the palpebral
reflex was 44 ± 13.2 minutes, and mean time to
walking was 55 ± 16.6 minutes. Time to onset of
effects was not associated with dose, but recovery
times were prolonged with higher doses of rocuronium.
Cardiac arrhythmias were observed in 13
Conclusions and Clinical Relevance—Administration
of rocuronium at a dose of 0.25 to 0.5 mg/kg is
a safe and effective adjunct to general anesthesia in
Gulf Coast box turtles. Because rocuronium does
not provide any analgesic or sedative effects, the
duration of neuromuscular blockade without anesthesia
should be minimized to avoid undue distress.
(J Am Vet Med Assoc 2003;222:1111–1115)
Objective—To evaluate the effect of a soy-based diet on general health and adrenocortical and thyroid gland function in dogs.
Animals—20 healthy privately owned adult dogs.
Procedures—In a randomized controlled clinical trial, dogs were fed a soy-based diet with high (HID; n = 10) or low (LID; 10) isoflavones content. General health of dogs, clinicopathologic variables, and serum concentrations of adrenal gland and thyroid gland hormones were assessed before treatment was initiated and up to 1 year later. Differences between groups with respect to changes in the values of variables after treatment were assessed by means of a Student t test (2 time points) and repeated-measures ANOVA (3 time points).
Results—No differences were detected between the 2 groups with respect to body condition and results of hematologic, serum biochemical, and urine analyses. Most serum concentrations of hormones did not change significantly after treatment, nor were they affected by diet. However, the mean change in serum concentration of total thyroxine was higher in the HID group (15.7 pmol/L) than that in the LID group (–1.9 pmol/L). The mean change in estradiol concentration after ACTH stimulation at 1 year after diets began was also higher in the HID group (19.0 pg/mL) than that in the LID group (–5.6 pg/mL).
Conclusions and Clinical Relevance—Phytoestrogens may influence endocrine function in dogs. Feeding soy to dogs on a long-term basis may influence results of studies in which endocrine function is evaluated, although larger studies are needed to confirm this supposition.