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Abstract

OBJECTIVE To identify courses in which first-year veterinary students struggled academically and to survey veterinarians as to their opinions on existing prerequisite courses and proposed alternatives.

DESIGN Electronic surveys.

SAMPLE Associate deans for academic affairs at colleges of veterinary medicine and practicing veterinarians in North America and the Caribbean.

PROCEDURES Surveys were sent to associate deans of academic affairs seeking information on courses in which first-year veterinary students most commonly struggled academically. The 6 courses most commonly listed as prerequisites for admission to veterinary college were identified, and practitioners were asked to rank the relative importance of those courses for preparing students for veterinary college and to rank the importance of 7 potential alternative courses.

RESULTS Data were obtained from 21 associate deans and 771 practicing veterinarians. First-year veterinary students most commonly struggled academically in anatomy, physiology, and histology courses, but these courses were rarely included as prerequisites for admission. Practicing veterinarians agreed that anatomy and physiology should be considered as possible alternatives to 1 or more current prerequisite courses, such as organic chemistry and physics.

CONCLUSIONS AND CLINICAL RELEVANCE First-year veterinary students commonly encountered academic difficulties in anatomy, physiology, and histology. Because few surveyed veterinary colleges include these courses as prerequisites for admission, many students were exposed to this material for the first time as veterinary students, potentially adding to their academic difficulties and causing stress and anxiety. To help address this situation, veterinary colleges might consider replacing 1 or more current prerequisite courses (eg, organic chemistry and physics) with anatomy, physiology, and histology.

Restricted access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine messenger RNA expression of cyclooxygenase (COX)-2, tumor necrosis factor (TNF)-α, and interleukin- (IL)-1β from cultured equine smooth muscle cells (SMC).

Sample Population—Segments of palmar digital artery harvested from 6 clinically normal adult horses.

Procedure—Explants were collected from the tunica media of arteries for primary culture of SMC. Equine mononuclear cells were used as control cells. Subcultured vascular SMC and control cells were exposed to lipopolysaccharide (20 µg/ml and 100 ng/ml, respectively). Northern blot analysis with equine-specific probes for COX-2, TNF-α, and IL-1β was performed, using isolated total cellular RNA.

Results—Although no message was detected for IL-1β or TNF-α in control or endotoxin-exposed equine vascular SMC from all horses, COX-2 underwent a distinct substantial up-regulation after endotoxin exposure. Endotoxin-exposed equine mononuclear cells had up-regulation of IL-1β and TNF-α mRNA.

Conclusions and Clinical Relevance—Increased expression of COX-2 mRNA by equine vascular SMC may be an important early pathophysiologic event in the onset of endotoxemia in horses. Potentiated local vascular production of various prostanoids after increased expression of mRNA for COX-2 may result in vasoactive events observed with laminitis. (Am J Vet Res 2001;62:1957–1963)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine the effect of fetal bovine serum (FBS) and heat-inactivated FBS (HI-FBS) on lipopolysaccharide (LPS)- and zymosan-induced procoagulant activity of equine and canine mononuclear cells.

Sample Population—Mononuclear cells from 18 horses and 3 dogs.

Procedures—Cells were incubated with various concentrations of FBS, HI-FBS, LPS, zymosan, polymyxin B, and anti–LPS-binding protein monoclonal antibody or combinations of these constituents. A 1stage recalcification assay was used to determine procoagulant activity.

Results—Addition of FBS to media significantly increased procoagulant activity; equine and canine cells were stimulated by 1% and 10% FBS, respectively. Coincubation of cells with FBS and polymyxin B did not reduce this effect, suggesting that the response was not attributable to LPS contamination. Addition of HI-FBS to media did not stimulate procoagulant activity of equine or canine cells, and the sensitivity of the equine cells to LPS was significantly increased by HI-FBS. This increased LPS sensitivity was reduced 40% with monoclonal antibody directed against human recombinant LPSbinding protein. Increasing concentrations of HIFBS significantly increased LPS- and zymosaninduced procoagulant activity of canine cells.

Conclusion and Clinical Relevance—Procoagulant activity production in equine and canine mononuclear cells was significantly increased by addition of FBS, whereas heat inactivation of FBS eliminated this effect. Heat inactivation did not eliminate the function of serum proteins involved in enhancement of LPSand zymosan-induced procoagulant activity. Results suggest that HI-FBS can be used as a source of serum proteins that increase the sensitivity of mononuclear cells to bacterial and yeast cell wall components.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine the effects of induction of capacitative Ca2+ entry on tone in equine laminar arteries and veins.

Sample Population—Laminar arteries and veins from 6 adult mixed-breed horses.

Procedure—Arteries and veins were isolated and mounted on small vessel myographs for the measurement of isometric tension. Capacitative Ca2+ entry was induced by incubating the vessels with the specific Ca2+-ATPase inhibitor thapsigargin (100nM) in a Ca2+- free physiologic salt solution. Capacitative Ca2+ entry–associated contractile responses were determined by the subsequent addition of 2mM Ca2+ to the solution bathing the vessels; in some experiments, either the voltage-gated Ca2+ blocker diltiazem (10µM) or the putative capacitative Ca2+ entry inhibitor trifluoromethylphenylimidazole (300µM) was added to the bathing solution 15 minutes prior to a second 2mM Ca2+ exposure. The Sr2+ permeability of the capacitative Ca2+ entry pathway in laminar vessels was assessed by exposing the vessels to 4mM Sr2+ after induction of capacitative Ca2+ entry with thapsigargin.

Results—Induction of capacitative Ca2+ entry elicited robust contractile responses in laminar veins but did not increase tone in laminar arteries. In laminar veins, capacitative Ca2+ entry–induced contractile responses were unaffected by preincubation with diltiazem, attenuated by trifluoromethylphenylimidazole, and were impermeable to Sr2+.

Conclusions and Clinical Relevance—Results indicated that induction of capacitative Ca2+ entry elicits vasoconstriction in equine laminar veins but not in laminar arteries and should therefore be considered a potential mechanism by which selective venoconstriction occurs in horses during the development of acute laminitis. (Am J Vet Res 2005;66:1877–1880)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate effects of black walnut extract (BWE) on equine mononuclear cells and determine whether BWE has direct proinflammatory effects.

Sample—Mononuclear cells separated from blood samples from 8 horses.

Procedures—Aqueous BWE was prepared and processed to eliminate contamination with particulates and microbes. A Limulus amoebocyte lysate assay was used to detect lipopolysaccharide (LPS) contamination in the BWE. Mononuclear cells were incubated in minimal essential medium with or without the addition of 0.6% to 10% (vol/vol) BWE. These mononuclear cells were assessed for viability, activities of caspases 3 and 7, nitric oxide production, procoagulant activity, and tumor necrosis factor-α production. The effect of LPS on cellular responses induced by BWE was assessed by coincubation with 13 U of polymyxin B/mL; mononuclear cells incubated with LPS were used as a reference.

Results—BWE did not cause loss of cell membrane integrity in mononuclear cells but did induce a dose-dependent increase in activities of caspases 3 and 7. Neither BWE nor LPS significantly induced production of nitric oxide. Both BWE and LPS induced comparable amounts of procoagulant activity and tumor necrosis factor-α production; coincubation with polymyxin B reduced the activity for BWE and LPS by 50% and approximately 100%, respectively.

Conclusions and Clinical Relevance—Addition of BWE induced inflammatory activation of equine mononuclear cells, a portion of which was independent of the effects of LPS. Furthermore, BWE and LPS may work in concert to induce systemic inflammatory responses that contribute to the development of acute laminitis in horses.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To study expression of interleukin-1beta (IL-1β) in the digital laminae of horses in the prodromal stage of experimentally induced laminitis.

Animals—8 healthy adult horses with no signs of laminitis.

Procedure—Black walnut extract was administered via nasogastric tube to 4 horses, and water was administered to the remaining 4 (controls). Complete blood counts and physical examinations were performed every 30 minutes after administration of black walnut extract or water. General anesthesia was induced when total WBC count decreased by 30% in horses given the black walnut extract and 3 hours after water administration in control horses. The left forefoot was perfusion fixed with neutral-buffered 10% formalin, and paraffin-embedded sections of the digit were used for in situ hybridization with an equine-specific IL-1β probe.

Results—IL-1β mRNA expression was observed in perivascular cells of the small laminar venules and capillaries in all 4 horses given black walnut extract and in interstitial cells remote from the microvasculature in 1 of the 4. Other cellular components of the laminar tissue and cellular components of the digital arterioles and veins did not exhibit IL-1β mRNA expression. Expression of IL-1β mRNA was not detected in laminae from control horses.

Conclusions and Clinical Relevance—Results suggest that IL-1β mRNA is expressed by perivascular cells in the laminar tissues of horses in the prodromal stage of experimentally induced laminitis. This provides evidence of an inflammatory process during the prodromal stage of laminitis, indicating that local digital proinflammatory cytokine expression may be an initiating factor in laminitis.(Am J Vet Res 2001;62: 714–720)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine concentrations of 2 acute-phase proteins (serum amyloid A [SAA] and lipopolysaccharide-binding protein [LBP]) in serum samples obtained from horses with colic and identify relationships among these acute-phase proteins and clinical data.

Animals—765 horses with naturally developing gastrointestinal tract diseases characterized by colic (ie, clinical signs indicative of abdominal pain) and 79 healthy control horses; all horses were examined at 2 university teaching hospitals.

Procedure—Serum concentrations of SAA and LBP were determined by immunoturbidometric and dotblot assays, respectively.

Results—SAA and LBP concentrations were determined for 718 and 765 horses with colic, respectively. Concentrations of SAA were significantly higher in nonsurvivors than in survivors, and horses with enteritis or colitis and conditions characterized by chronic inflammation (eg, abdominal abscesses, peritonitis, or rectal tears) had SAA concentrations significantly greater than those for horses with other conditions. Serum concentrations of LBP did not correlate with outcome, disease process, or portion of the gastrointestinal tract affected.

Conclusions and Clinical Relevance—Circulating concentrations of SAA were significantly higher at admission in horses with colic attributable to conditions having a primary inflammatory cause (eg, enteritis, colitis, peritonitis, or abdominal abscesses) and were higher in horses that failed to survive the episode of colic, compared with concentrations in horses that survived. Serum concentrations of LBP did not correlate with survival. Analysis of these findings suggests that evaluation of SAA concentrations may be of use in identifying horses with colic attributable to diseases that have inflammation as a primary component of pathogenesis. (Am J Vet Res 2005;66:1509–1516)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To investigate the effect of ex vivo exposure to lipopolysaccharide (LPS) on the expression of inflammatory genes in leukocytes from horses with gastrointestinal (Gl) disease and determine whether the pattern or magnitude of the response to LPS correlated with the type of disease and outcome.

Animals—49 horses with Gl disease and 10 healthy horses

Procedures—Leukocytes were isolated from blood samples and submitted to 3 protocols: immediate freezing, freezing after 4-hour incubation in medium, and freezing after 4-hour incubation in medium containing LPS. Expression of 14 genes associated with inflammation was assessed via PCR assay. Results were compared by disease type and outcome

Results—Horses with Gl disease had colic of unknown etiology (n = 8), Gl inflammation or strangulation (18), or nonstrangulating Gl obstruction (23). Among the 44 horses receiving treatment, 38 were discharged from the hospital and 6 died or were euthanized. Incubation of leukocytes in medium alone changed the expression of several genes. Incubation with LPS resulted in increased expression of interleukin-10 and monocyte chemotactic protein-3 in leukocytes from healthy and sick horses. Leukocytes from horses with nonstrangulating obstruction and horses that survived had less pronounced LPS-induced increases in interleukin-10 expression than did cells from healthy horses. The opposite was evident for monocyte chemotactic protein-3.

Conclusions and Clinical Relevance—No evidence existed for a reduced response of leukocytes from horses with gastrointestinal disease to ex vivo exposure to LPS. Leukocyte expression of inflammatory genes after ex vivo incubation with LPS appeared to be related to pathogenesis and prognosis. (Am J Vet Res 2010;71:1162—1169)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To investigate whether expression of inflammation-associated genes in leukocytes from horses with gastrointestinal tract (GIT) diseases correlated with the type of disease and outcome.

Animals—10 healthy horses and 50 horses with GIT disease.

Procedures—A blood sample was collected from each healthy horse or horse with GIT disease (during admission to the hospital). Leukocytes were isolated, diluted to a standard concentration, and frozen until RNA extraction. Expression of 14 genes associated with inflammation was quantified by use of a real-time quantitative reverse transcription PCR assay. Results were grouped by GIT disease type and disease outcome for comparison.

Results—Horses with GIT disease had colic of unknown etiology (n = 8 horses), GIT inflammation or strangulation (19), or nonstrangulating GIT obstruction (23). Among the 45 horses receiving treatment, 38 were discharged from the hospital, and 7 died or were euthanized. Compared with healthy horses, horses with colic of unknown etiology had similar gene expression. Significant differences in expression of the interleukin-8, leukocyte-selectin molecule, matrix metalloproteinase-9, platelet-selectin molecule, mitochondrial superoxide dismutase, Toll-like receptor 4, and tumor necrosis factor-A genes were detected between healthy horses and horses with GIT disease. Significant differences in expression of the interleukin-1 receptor antagonist, interleukin-8, leukocyte-selectin molecule, matrix metalloproteinase-9, platelet-selectin molecule, mitochondrial superoxide dismutase, Toll-like receptor 4, and tumor necrosis factor-A genes were detected among healthy horses and horses grouped by disease outcome.

Conclusions and Clinical Relevance—Inflammatory gene expression in leukocytes of horses with GIT disease appeared to be related to disease pathogenesis and prognosis.

Full access
in American Journal of Veterinary Research

Abstract

Objective—To provide insights into the role of prostaglandin F (PGF) in the developmental stages of laminitis induced in horses by ingestion of black walnut heartwood extract (BWHE).

Sample Population—10 adult mixed-breed horses.

Procedures—Horses were separated into 2 groups and were euthanatized at 12 hours after placebo (water) administration (control horses) or after BWHE administration and development of Obel grade 1 laminitis. Blood samples were obtained to determine plasma PGF concentrations hourly for the first 4 hours and subsequently every 2 hours after substance administration. Laminar arteries and veins were isolated, and responses to increasing concentrations of PGF were measured before and after preincubation of blood vessels with prostanoid and thromboxane receptor antagonists SQ 29,548, SC-19220, and AH 6809.

Results—Plasma PGF concentrations increased in horses given BWHE; the WBC count decreased concurrently. In control horses, PGF was a potent contractile agonist for laminar veins but not for laminar arteries. In horses given BWHE, PGF was similarly selective for laminar veins; however, the magnitude of PGF-induced venoconstriction was less than that in control horses. After preincubation with SQ 29,548, laminar veins from control horses responded to PGF with a small degree of dilation, whereas laminar veins from horses given BWHE did not.

Conclusions and Clinical Relevance—PGF may play a role in the inflammatory and vascular dysfunction associated with the prodromal stages of laminitis. Prostanoids such as PGF may be viable targets for the prevention of acute laminitis in horses.

Full access
in American Journal of Veterinary Research