Objective—To determine and compare the number,
type, location, and distribution of apoptotic epidermal
cells in the laminae of clinically normal horses and
horses with laminitis.
Sample Population—Formalin-fixed samples of digital
lamellar tissue from 47 horses (including clinically
normal horses [controls; n = 7], horses with acute 
and chronic  naturally acquired laminitis, and horses
with black walnut extract-induced  or carbohydrate
overload-induced  laminitis).
Procedure—Blocks of paraffin-embedded lamellar tissues
were stained for DNA fragmentation with the
terminal deoxynucleotidyl transferase-mediated dUTP
nick-end labeling (TUNEL) technique. Differential
immunohistochemical staining for caspases 3 and 14
were used to confirm apoptosis.
Results—The number of TUNEL-positive epidermal
cells per 0.1 mm of primary laminae was significantly
greater in the acute laminitis group than in the other
groups. In the acute laminitis group, there were 17
and 1,025 times as many TUNEL-positive basal layer
cells and keratinocytes, respectively, compared with
the control group. Apoptosis of TUNEL-positive basal
layer cells was confirmed by results of caspase 3
immunohistochemical staining. The TUNEL-positive
keratinocytes did not stain for caspases 3 or 14.
Conclusions and Clinical Relevance—The large
number of apoptotic basal layer cells detected in the
lamellar tissue of horses with acute naturally acquired
laminitis suggests that apoptosis may be important in
the development of acute laminitis. The role of the
large number of TUNEL-positive keratinocytes detected
in the interface of primary and secondary epidermal
laminae of horses with acute laminitis remains to
be elucidated. ( Am J Vet Res 2004;65:578–585)
Objective—To characterize the in vitro response of
equine cecal longitudinal smooth muscle (CLSM) to
endothelin (ET)-1 and assess the role of ETA and ETB
receptors in those ET-1–induced responses.
Animals—36 horses without gastrointestinal tract
Procedure—To determine cumulative concentrationresponse
relationships, CLSM strips were suspended
in tissue baths containing graded concentrations of
ET-1 (10–9 to 10–6M) with or without BQ-123 (ETA
receptor antagonist); with or without IRL-1038 (ETB
receptor antagonist); or with both antagonists at concentrations
of 10–9, 10–7, and 10–5M. To determine the
percentage change in baseline tension of CLSM, the
areas under the curve during the 3-minute periods
before and after addition of each dose were compared
. Also, the effects of ET-1 and a combination of
selective ETA and ETB receptor antagonists on electrically
evoked contractions were studied.
Results—ET-1 caused sustained increases in CLSM
tension in a concentration-dependent manner.
Contractile responses to ET-1 were not significantly
inhibited by either BQ-123 or IRL-1038 alone at any
concentration; however, responses were significantly
inhibited by exposure to the antagonists together at a
concentration of 10–5M. Electrical field stimulation did
not change the spontaneous contractile activity of
CLSM and did not significantly alter the tissue
response to ET-1, BQ-123, or IRL-1038.
Conclusions and Clinical Relevance—Results indicated
that ET-1 has a contractile effect on equine CLSM
that is mediated via ETA and ETB receptors. In vitro
spontaneous contractions of equine CLSM apparently
originate in the smooth muscle and not the enteric nervous
system. (Am J Vet Res 2005;66:1202–1208)
Objective—To identify differentially expressed genes in pulmonary tissues of horses affected with summer pasture-associated obstructive pulmonary disease (SPAOPD), which is a form of recurrent airway obstruction (RAO), compared with those of unaffected horses.
Animals—6 horses with SPAOPD-RAO and 6 unaffected (healthy) horses.
Procedures—Horses were assigned to 2 groups on the basis of medical history, clinical score, and transpleural pressure. Total RNA from each of the 5 lung lobes of each of the 6 SPAOPD-RAO–affected horses was extracted and pooled. Similarly, total RNA from unaffected horses was pooled. Differential display (DD) PCR assay was performed, and differentially expressed bands were purified and cloned into a plasmid vector. Plasmids were extracted from recombinant colonies, and purified DNA was sequenced. Genes of interest for RAO pathogenesis were identified. Real-time PCR assay was performed to confirm findings for the DD PCR assay.
Results—18 differentially expressed genes (17 upregulated and 1 downregulated) were identified. Three genes of particular interest were found to be altered (2 upregulated and 1 downregulated) in horses with SPAOPD-RAO by use of real-time PCR assay, and these findings matched the differential expression found by use of the DD PCR assay.
Conclusions and Clinical Relevance—SPAOPD-RAO in horses is a multifactorial, complex disease involving several genes. Upregulated genes, particularly β2-microglobulin, and the downregulated secretoglobin gene can serve as marker genes that may help to identify SPAOPD-RAO at an early age.
To evaluate the effects of a cognitive-behavioral skills building program (ie, MINDSTRONG; The Ohio State University) on the mental health outcomes and healthy lifestyle beliefs and behaviors of Doctor of Veterinary Medicine (DVM) students.
DVM students (n = 62) before beginning their program at a large public Midwest land-grant university.
All 171 incoming DVM students (class of 2024) were required to take the cognitive-behavioral skills building program (7 weeks in length) before starting their 2020 school year. Students were given the option to consent to the study portion of the program. Consenting participants completed a pre- and postsurvey containing demographic questions and 5 valid and reliable scales, including the Patient Health Questionnaire-9 that assesses depressive symptoms, the Generalized Anxiety Disorder-7 that evaluates anxiety, the Brief Inventory of Perceived Stress that measures stress, and the Healthy Lifestyle Beliefs and Healthy Lifestyle Behaviors scales. Descriptive statistics described sample characteristics, paired t tests assessed changes over time in the outcomes Personal Wellness Assessment, and Cohen’s d determined effect sizes.
62 DVM students completed both surveys. Postintervention, students had significant improvements in depressive symptoms, anxiety, and healthy lifestyle beliefs and behaviors.
Although this study used a small convenience sample of DVM students from a single university, a cognitive-behavioral skills building program demonstrated the ability to decrease rates of depression, anxiety, and suicidal ideation and improve healthy lifestyle beliefs and behaviors. Requiring DVM students to participate in such programming could provide benefit during their professional education and throughout their careers.
Objective—To characterize alterations in systemic
and local colonic hemodynamic variables associated
with IV infusion of ATP-MgCl2 in healthy anesthetized
Animals—12 adult horses.
Procedure—Six horses were given ATP-MgCl2, IV,
beginning at a rate of 0.1 mg of ATP/kg of body
weight/min with incremental increases until a rate of
1.0 mg/kg/min was achieved. The remaining 6 horses
were given an equivalent volume of saline (0.9%
NaCl) solution over the same time period. Colonic and
systemic hemodynamic variables and colonic plasma
nitric oxide (NO) concentrations were determined
before, during, and after infusion.
Results—Infusion of ATP-MgCl2 caused a rate-dependent
decrease in systemic and colonic vascular resistance,
principally via its vasodilatory effects. A rate of
0.3 mg of ATP/kg/min caused a significant decrease in
systemic and colonic arterial pressure and colonic vascular
resistance without a significant corresponding
decrease in colonic arterial blood flow. Consistent alterations
in NO concentrations of plasma obtained from
colonic vasculature were not detected, despite profound
vasodilatation of the colonic arterial vasculature.
Conclusions and Clinical Relevance—Results
revealed that IV infusion of ATP-MgCl2 may be beneficial
in maintaining colonic perfusion in horses with
ischemia of the gastrointestinal tract, provided a sufficient
pressure gradient exists to maintain blood flow.
(Am J Vet Res 2001;62:1240–1249)
Objective—To determine concentrations of nitric
oxide (NO) in plasma and bronchoalveolar lavage fluid
(BALF) and localize nitric oxide synthesis in the lungs
of horses with summer pasture-associated obstructive
pulmonary disease (SPAOPD).
Animals—7 adult horses with SPAOPD and 6 clinically
normal adult horses.
Procedure—Severity of SPAOPD was determined by
use of clinical scores, change in intrapleural pressure
(ΔPpl) during tidal breathing, cytologic analysis of
BALF, and histologic evaluation of lung specimens
obtained during necropsy. Nitric oxide concentrations
in plasma, BALF, and epithelial lining fluid (ELF) were
determined by use of a chemiluminescent method.
Inducible nitric oxide synthase (iNOS) and nitrotyrosine
(NT) were localized in formalin-fixed lung specimens
by use of immunohistochemical staining, and
nicotinamide adenine dinucleotide phosphate
diaphorase (NADPHd) activity was localized in cryopreserved
specimens by use of histochemical staining.
Results—Plasma concentration of NO in affected
horses was slightly but not significantly greater than
concentration in nonaffected horses. Nitric oxide concentrations
in BALF or ELF did not differ between
groups. Immunoreactivity of iNOS in bronchial epithelial
cells of 3 of 5 lung lobes was greater in horses
with SPAOPD, compared with nonaffected horses.
However, staining for NT and NADPHd activity did not
differ between groups.
Conclusions and Clinical Relevance—Expression of
iNOS was greater in bronchial epithelial cells of horses
with SPAOPD, compared with nonaffected horses,
suggesting that NO may play a role in amplifying the
inflammatory process in the airways of horses with
this disease. (Am J Vet Res 2001;62:1381–1386)
Objective—To evaluate the in vitro effects of adenosine
tryphosphate (ATP) on vasomotor tone of equine
Sample Population—Arteries and veins from the left
ventral colon of 14 mixed-breed horses euthanatized
for reasons unrelated to cardiovascular or gastrointestinal
Procedures—Endothelium-intact and -denuded arterial
and venous rings were precontracted with 10–7 and
1.8 × 10–8M endothelin-1, respectively. In 1 trial,
endothelium-intact rings were also incubated with
10–4M Nω-nitro-L-arginine methyl ester (L-NAME) to
inhibit nitric oxide (NO) production. Adenosine
triphosphate (10–8 to 10–3M) was added in a noncumulative
manner, and relaxation percentage versus time
curves were generated. Areas under the curves (ie,
percentage of relaxation time) were calculated.
Results—Relaxation response of arterial and venous
rings to ATP was dose-dependent. Percentage of
relaxation time in response to 10–4 and 10–3M ATP was
significantly greater, compared with that for rings not
treated with ATP. Removal of endothelium attenuated
but did not eliminate the relaxation response. Addition
of L-NAME did not attenuate the relaxation response
in arteries. At higher concentrations, the vascular
response to ATP was biphasic.
Conclusions and Clinical Relevance—ATP applied to
equine colonic arterial and venous rings with and without
intact endothelium induced a biphasic response
characterized by transient contraction followed by slow,
substantial, and sustained relaxation. This ATP-induced
response is possibly mediated by a mechanism other
than NO. Adenosine triphosphate may be a useful
treatment to modulate colonic vasomotor tone in horses
with strangulating volvulus of the ascending colon.
(Am J Vet Res 2001;62:1928–1933)