Objective—To determine effects of prior feeding on
pharmacokinetics and estimated bioavailability of orally
administered microencapsulated erythromycin
base (MEB) in healthy foals.
Animals—6 healthy foals, 3 to 5 months old.
Procedure—Foals were given 2 doses of MEB (25
mg/kg of body weight, PO). One dose was administered
after food was withheld overnight, and the other
was administered after foals had consumed hay. The
study used a crossover design with a 2-week period
between doses. Blood was collected via a jugular vein
prior to and at specific times after drug administration.
Concentrations of erythromycin A and anhydroerythromycin
A in plasma were determined, using highperformance
liquid chromatography. Results pharmacokinetic
analysis of plasma concentration-time data
for food-withheld and fed conditions were compared.
Results—Plasma concentrations of erythromycin A
for foals were lower after feeding than concentrations
when food was withheld. Area under the plasma concentration-
time curve, maximum plasma concentration,
and estimated bioavailability were greater in
foals when food was withheld than when foals were
fed. Anhydroerythromycin A was detected in plasma
after administration of MEB in all foals.
Conclusions and Clinical Relevance—Foals should
be given MEB before they are fed hay. Administration
of MEB to foals from which food was withheld
overnight apparently provides plasma concentrations
of erythromycin A that exceed the minimum inhibitory
concentration of Rhodococcus equi for approximately
5 hours. The dosage of 25 mg/kg
every 8 hours, PO, appears appropriate. (Am J Vet
Objective—To determine pharmacokinetics and plasma
concentrations of erythromycin and related compounds
after intragastric administration of erythromycin
phosphate and erythromycin estolate to
Animals—11 healthy 2- to 6-month-old foals.
Procedure—Food was withheld from foals overnight
before intragastric administration of erythromycin
estolate (25 mg/kg of body weight; n = 8) and erythromycin
phosphate (25 mg/kg; 7). Four foals received
both drugs with 2 weeks between treatments.
Plasma erythromycin concentrations were determined
at various times after drug administration by
use of high-performance liquid chromatography.
Maximum plasma peak concentrations, time to maximum
concentrations, area under plasma concentration
versus time curves, half-life of elimination, and
mean residence times were determined from concentration
versus time curves.
Results—Maximum peak concentration of erythromycin
A after administration of erythromycin phosphate
was significantly greater than after administration
of erythromycin estolate (2.9 ± 1.1 µg/ml vs 1.0 ±
0.82 µg/ml). Time to maximum concentration was
shorter after administration of erythromycin phosphate
than after erythromycin estolate (0.71 ± 0.29
hours vs 1.7 ± 1.2 hours). Concentrations of anhydroerythromycin
A were significantly less 1 and 3
hours after administration of erythromycin estolate
than after administration of erythromycin phosphate.
Conclusions and Clinical Relevance—Plasma concentrations
of erythromycin A remained > 0.25 µg/ml
(reported minimum inhibitory concentration for Rhodococcus equi) for at least 4 hours after intragastric
administration of erythromycin phosphate or erythromycin
estolate, suggesting that the recommended
dosage for either formulation (25 mg/kg, q 6 h) should
be adequate for treatment of R equi infections in foals.
(Am J Vet Res 2000;61:914–919)
Objective—To characterize gelatinases in bronchoalveolar
lavage fluid (BALF) and gelatinases produced
by alveolar macrophages of healthy calves.
Sample Population—Samples of BALF and alveolar
macrophages obtained from 20 healthy 2-month-old
Procedure—BALF was examined by use of gelatin
zymography and immunoblotting to detect gelatinases
and tissue inhibitor of metalloproteinase (TIMP)-1
and -2. Cultured alveolar macrophages were stimulated
with lipopolysaccharide (LPS), and conditioned
medium was subjected to zymography. Alveolar
macrophage RNA was used for reverse transcriptasepolymerase
chain reaction assay of matrix metalloproteinases
(MMPs), cyclooxygenase-2, and inducible
nitric oxide synthase.
Results—Gelatinolytic activity in BALF was evident at
92 kd (14/20 calves; latent MMP-9) and 72 kd (18/20;
latent MMP-2). Gelatinolytic activity was evident at 82
kd (10/20 calves; active MMP-9) and 62 kd (17/20;
active MMP-2). Gelatinases were inhibited by metal
chelators but not serine protease inhibitors.
Immunoblotting of BALF protein and conditioned
medium confirmed the MMP-2 and -9 proteins.
Endogenous inhibitors (ie, TIMPs) were detected in
BALF from all calves (TIMP-1) or BALF from only 4
calves (TIMP-2). Cultured alveolar macrophages
expressed detectable amounts of MMP-9 mRNA but
not MMP-2 mRNA.
Conclusions and Clinical Relevance—Healthy
calves have detectable amounts of the gelatinases
MMP-2 and -9 in BALF. Endogenous inhibitors of
MMPs were detected in BALF (ie, TIMP-1, all calves;
TIMP-2, 4 calves). Lipopolysaccharide-stimulated alveolar
macrophages express MMP-9 but not MMP-2
mRNA. The role of proteases in the pathogenesis of
lung injury associated with pneumonia has yet to be
determined. (Am J Vet Res 2004;65:163–172)
Objective—To evaluate the effect of lactoferrin on lipopolysaccharide (LPS)-induced proliferation of bovine peripheral blood mononuclear cells (PBMCs), gene expression of inflammatory mediators, and production of prostanoids in vitro.
Sample Population—PBMCs isolated from 15 Holstein bull calves.
Procedures—Mixed populations of PBMCs were isolated by differential centrifugation. Proliferation assays were conducted in 96-well plates designed to allow addition of lactoferrin (200 ng/mL) with and without LPS (1 μg/mL) in a checkerboard design. Incorporation of 3H-thymidine was used to determine proliferation of PBMCs. Prostaglandin E2 production was determined in culture-conditioned medium by use of enzyme immunoassay. Effects of lactoferrin on LPS-induced gene expression of cyclooxygenase (COX)-2 and matrix metalloproteinase (MMP)-9 were monitored by use of PCR assays.
Results—Lactoferrin supplementation significantly reduced LPS-induced incorporation of 3H-thymidine and production of prostaglandin E2 by PBMCs. Lactoferrin reduced LPS-induced expression of COX-2 and MMP-9 mRNA.
Conclusions and Clinical Relevance—Lactoferrin reduced LPS-induced cellular proliferation, inflammatory mediator gene expression, and prostaglandin E2 production by bovine PBMCs in vitro. These effects may be beneficial in reducing the impact of endotoxemia in neonates.
Objective—To determine the effects of pasteurization
of colostrum on serum lactoferrin concentration and
neutrophil oxidative function by comparing values
from calves given pasteurized (76 C, 15 minutes)
colostrum versus calves given fresh frozen colostrum.
Animals—8 Holstein bull calves were used to study
the effects of pasteurization of colostrum on the
absorption of lactoferrin and neutrophil oxidative burst.
Three additional calves were used to study the effect
of exogenous lactoferrin on neutrophil oxidative burst.
Methods—Calves were fed fresh frozen or heat pasteurized
colostrum (76 C for 15 minutes) via
esophageal feeder within 4 hours of birth. Neutrophils
were isolated from whole blood samples. Neutrophil
oxidative burst was induced by phorbol ester (300
ng/ml) stimulation of cells (1 × 106 cells) at 37 C.
Serum lactoferrin concentrations were compared,
using immunoblot analysis. Serum IgG concentrations
were determined by radial immunoassay.
Comparisons were made between the use of the 2
types of colostrum in calves by measuring subsequent
serum IgG and lactoferrin concentrations and
neutrophil superoxide production.
Results—Serum IgG and lactoferrin concentrations
increased more in calves receiving fresh frozen
colostrum. Neutrophil superoxide production was higher
in neutrophils prepared from calves receiving fresh
frozen colostrum. Colostral lactoferrin addition to neutrophil
incubations resulted in increased oxidative burst.
Conclusions and Clinical Relevance—Compared
with calves given fresh frozen colostrum, calves given
pasteurized colostrum had decreased serum IgG and
lactoferrin concentrations and neutrophil superoxide
production 24 hours after administration. These
results suggest that pasteurizing bovine colostrum at
76 C for 15 minutes has substantial effects on passive
transfer of proteins and neutrophil function. (Am J Vet
Objective—To characterize and purify covalent complexes of matrix metalloproteinase-9 (MMP-9) and haptoglobin released by bovine granulocytes in vitro.
Sample Population—Blood samples obtained from healthy cows and cows with acute and chronic inflammation to obtain WBCs and sera.
Procedures—WBCs were isolated by differential centrifugation, hypotonic lysis of RBCs, and degranulated by stimulation with phorbol ester (20 ng/mL). Cell-conditioned medium was subjected to affinity and gel chromatography and purified proteins subjected to SDS- PAGE gelatin zymography, western blot analysis, Coomassie blue staining, and peptide mass spectrometry for protein identification. Sera of cows hospitalized for acute and chronic septic conditions and of clinically normal cows were analyzed with similar methods.
Results—Matrix metalloproteinase-9 was released from neutrophils in vitro and migrated to a molecular mass of approximately 220 kd (prodimer), approximately 105 kd (promonomer), and > 220 kd (high–molecular mass complexes). These high–molecular mass complexes were composed of α- and β-haptoglobin and MMP-9 (ratio13:13:1). Complexes of MMP-9 and haptoglobin had biochemical properties of both its protein constituents (ie, enzymatic activity toward gelatin and hemoglobin binding). Complexes of MMP-9 and haptoglobin were also detected in sera of cows with acute inflammation, but not in clinically normal cows or cows with chronic disease.
Conclusions and Clinical Relevance—A fraction of neutrophil MMP-9 is released in complex with haptoglobin. The complex is present in granules and retains biological activity of its components. Detection of the complex in serum may provide an indicator of acute inflammation.
OBJECTIVE To determine the extent of environmental exposure to heteroxenous coccidia from wild canid feces in southeastern Ohio.
SAMPLE 285 presumed wild canid fecal samples collected across an ecological system in southeastern Ohio.
PROCEDURES Morphological classification and molecular analysis were used to determine the canid genus for collected fecal samples. Microscopic and molecular analysis were used to detect coccidian oocysts and DNA. Several variables were analyzed for associations with coccidian DNA detection or prevalence.
RESULTS Coccidian DNA was detected in 51 of 285 (17.9%) fecal samples. Of those positive samples, 1% (95% confidence interval, 0.4% to 3%) had positive results for Hammondia heydorni and none had positive results for Neospora caninum, for an estimated environmental N caninum prevalence of 0% (95% confidence interval, 0% to 7%)/1-km2 hexagonal area evaluated. Morphological classification revealed that 78.9% (225/285) of fecal samples were from coyotes and 17.2% (49/285) were from foxes. No difference in proportions of coccidian DNA-positive fecal samples was identified among canid species. Environmental temperature and fecal freshness were associated with coccidian DNA detection. Land use type, relative canid density, and cattle density were not associated with the prevalence of coccidian DNA-positive samples.
CONCLUSIONS AND CLINICAL RELEVANCE The low prevalence of coccidia shed in wild canid feces in this study, including the estimated 0% environmental prevalence of N caninum, suggested that the role of the oocyst environmental phase in coccidia transmission to ruminants is likely minor in rural southeastern Ohio.