Objective—To assess pharmacokinetic and pharmacodynamic properties of dexamethasone administered PO as a solution or powder, compared with properties of dexamethasone solution administered IV, in apparently healthy horses.
Animals—6 adult horses.
Procedures—Serum cortisol concentration for each horse was determined before each treatment (baseline values). Dexamethasone (0.05 mg/kg) was administered PO (in solution or powdered form) or IV (solution) to horses from which feed had or had not been withheld (unfed and fed horses, respectively). Each horse received all 6 treatments in random order at 2-week intervals; PO and IV administrations of dexamethasone were accompanied by IV or PO sham treatments, respectively. Plasma dexamethasone and serum cortisol concentrations were assessed at predetermined intervals.
Results—Maximum plasma dexamethasone concentration after PO administration of powdered dexamethasone in unfed horses was significantly higher than the maximum plasma concentration after PO administration of dexamethasone solution in unfed or fed horses. Mean bioavailability of dexamethasone ranged from 28% to 66% but was not significantly different among horses receiving either formulation PO in the unfed or fed state. After dexamethasone treatment PO or IV, serum cortisol concentrations were significantly less than baseline at 1 to 72 hours in unfed horses and at 2 to 48 hours in fed horses.
Conclusions and Clinical Relevance—PO or IV administration of dexamethasone resulted in suppression of cortisol secretion in unfed and fed adult horses; the magnitude of suppression did not differ among treatment groups, and serum cortisol concentrations returned to baseline after 48 to 72 hours.
Objective—To evaluate clinical response, pulmonary
function, and adrenal gland response to incremental
doses of beclomethasone dipropionate in horses with
recurrent airway obstruction.
Animals—8 horses with recurrent airway obstruction.
Procedure—Horses randomly assigned to 4 groups
were treated twice daily via aerosol administration of
placebo or 500, 1,000, or 1,500 µg of beclomethasone
dipropionate in a crossover design with a 10-day
minimum washout period. Subjective assessment of
airway obstruction, serum cortisol concentration, and
maximum change in pleural pressure during tidal
breathing (ΔPplmax) were determined daily prior to
morning drug administration, and ΔPplmax was reevaluated
15 minutes after morning drug administration.
Pulmonary resistance and dynamic compliance were
determined at baseline and approximately 12 hours
after the final treatment.
Results—An immediate treatment effect was not
identified. Within 24 hours, ΔPplmax and airway
obstruction were lower in horses receiving
beclomethasone. Onset and magnitude of response
was similar among the 3 beclomethasone dose regimens.
Pulmonary resistance was improved only after
administration of all 3 doses of beclomethasone,
whereas dynamic compliance was improved after
administration of 1,000 µg and 1,500 µg of
beclomethasone. Reduction in serum cortisol concentration
occurred with all 3 beclomethasone dose
regimens; however, the magnitude of adrenal gland
suppression was greater in horses receiving 1,000 or
1,500 µg of beclomethasone.
Conclusions and Clinical Relevance—Low-dose
(500 µg) beclomethasone administration caused similar
improvement in pulmonary function, compared
with high-dose beclomethasone (1,000 and 1,500
µg), with the exception of dynamic compliance, and
caused less suppression of endogenous cortisol production.
(J Am Vet Med Assoc 2000;217:359–364)
Objective—To evaluate effects of trimethoprim-sulfamethoxazole
(T/SMX) on thyroid function in dogs.
Animals—6 healthy euthyroid dogs.
Procedure—Dogs were administered T/SMX (14.1 to
16 mg/kg, PO, q 12 h) for 3 weeks. Blood was collected
weekly for 6 weeks for determination of total
thyroxine (TT4), free thyroxine (fT4), and canine thyroid-
stimulating hormone (cTSH) concentrations.
Schirmer tear tests were performed weekly. Blood
was collected for CBC prior to antimicrobial treatment
and at 3 and 6 weeks.
Results—5 dogs had serum TT4 concentrations
equal to or less than the lower reference limit, and 4
dogs had serum fT4 less than the lower reference
limit after 3 weeks of T/SMX administration; cTSH
concentrations were greater than the upper reference
limit in 4 dogs. All dogs had TT4 and fT4 concentrations
greater than the lower reference limit
after T/SMX administration was discontinued for 1
week, and cTSH concentrations were less than reference
range after T/SMX administration was discontinued
for 2 weeks. Two dogs developed
decreased tear production, which returned to normal
after discontinuing administration.
Conclusions and Clinical Relevance—Results suggest
that administration of T/SMX at a dosage of 14.1 to
16 mg/kg, PO, every 12 hours for 3 weeks caused
decreased TT4 and fT4 concentrations and increased
cTSH concentration, conditions that would be compatible
with a diagnosis of hypothyroidism. Therefore, dogs
should not have thyroid function evaluated while receiving
this dosage of T/SMX for > 2 weeks. These results
are in contrast to those of a previous study of trimethoprim-
sulfadiazine. (Am J Vet Res 2005;66:256–259)
Objective—To determine hyaluronan concentrations in peritoneal fluid from healthy horses and horses with sudden signs of severe abdominal pain and to identify the cellular sources of hyaluronan within the peritoneal cavity.
Animals—7 client-owned horses that were evaluated for sudden signs of severe abdominal pain, 6 healthy teaching horses, and 13 euthanized horses (11 with no abdominal disease and 2 that had undergone abdominal surgery 2 weeks previously for a different study).
Procedures—Abdominal fluid was collected from the client-owned and teaching horses. Hyaluronan concentrations were determined with an ELISA. Equine mesothelial cells were aseptically harvested from euthanized horses immediately after euthanasia, cultured, and processed for western blot immunoassays to detect expression of the following mesothelial cell markers: cytokeratins 8 and 18, vimentin, calretinin, mesothelin, and CD44. A reverse transcriptase–PCR assay was used to detect genetic expression of hyaluronan synthase-2 (HAS-2) from cultured and native equine tissue.
Results—The mean ± SD abdominal hyaluronan concentration in peritoneal fluid from horses with signs of abdominal pain (1,203.3 ± 46.3 ng/mL) was significantly greater than that in healthy horses (228.4 ± 167.3 ng/mL). Harvested cells were maintained, and immunoblotting analyses confirmed expression of the mesothelial markers. Gene expression of HAS-2 from cultured mesothelial cells and fibroblasts was confirmed.
Conclusions and Clinical Relevance—Peritoneal hyaluronan concentration was much higher in horses with severe abdominal pain than in healthy horses. Cultured equine mesothelial cells and fibroblasts can produce hyaluronan through HAS-2. Future investigation should focus on establishing the effect of exogenous hyaluronan administration on mesothelial cell function in horses with abdominal disease.
Objective—To determine the level of clinical agreement
between 2 methods for the measurement of
resting energy expenditure (REE).
Design—Prospective case series.
Procedure—Oxygen consumption (O2) and CO2 production
(CO2) were measured with an open-flow indirect
calorimeter in healthy (n = 10) and ill (67) dogs.
Measurements were collected at 3 time periods on 2
days. The O2 and the CO2 measurements were then
used to calculate the REE values.
Results—Mean values of measured (MREE) and
predicted (PREE) REEs in healthy dogs and a dog
with medical illnesses or trauma were not significantly
different. There was a significant difference
on day 2 between the MREE and PREE in the group
of dogs recovering from major surgery. More importantly,
there was significant variation between the
PREE and MREE on an individual-dog basis. The
PREE only agreed to within ± 20% of the MREE in
51% to 57% of the dogs.
Conclusions and Clinical Relevance—The level of
agreement between these two methods for determining
the 24-hour REE was poor in individual dogs.
The level of disagreement between the 2 methods
indicates that these methods may not be used interchangeably
in a clinical setting. Measurement of REE
by use of indirect calorimetry may be the only reliable
method of determining REE in an individual ill or
healthy dog. (J Am Vet Med Assoc 2004;225:58–64)
The American Association of Veterinary Clinicians (AAVC) convened a Diversity, Equity, and Inclusivity working group in March 2021 to address the limited diversity (including but not limited to ethnic, racial, and cultural diversity) in clinical post-DVM graduate training programs and academic faculty. Concurrent with a working group formation, the AAVC developed a strategic plan. The central mission of the AAVC is to develop, support, and connect academic leaders to fuel the future of the veterinary medical profession. House officers and their training programs are central to all goals outlined in the strategic plan. Amongst other strategic goals, the working group identified best practices for intern and resident recruitment and selection. We report herein from the current health profession literature ways to identify and recruit talented, diverse candidates especially those with non-traditional (atypical) preparation and experience. We also provide recommendations on best practices for intern and resident selection. This document highlights holistic approaches, some of which are incrementally being incorporated into the Veterinary Intern Resident Matching Program application, that emphasize diversity as a selection criteria for intern and resident selection an important step towards building a more resilient and inclusive workforce. These include expanding candidate assessment beyond grades and class rank into a more standardized method for screening candidates that includes consideration of life experiences and talents outside of veterinary medicine.