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Summary

Stimulation of α2 adrenergic receptors inhibits colonic motility and may constrict some peripheral vascular beds. Endotoxemia elicits release of sympathetic neurotransmitters and increases sympathetic nerve activity, which may result in stimulation of α2 adrenergic receptors. The objective of this study was to determine whether blockade of α2 adrenergic receptors would restore cecal motility and blood flow during endotoxemia in horses. Strain-gauge force transducers and ultrasonic flow probes were used to measure cecal and colonic mechanical activity and lateral cecal arterial blood flow. Intravenous infusion of endotoxin (cumulative dose of 0.03 mg/kg) significantly decreased cecal and right ventral colon contractile activity and lateral cecal arterial blood flow. Slow iv infusion of yohimbine (cumulative dose of 75 μg/kg) significantly attenuated those effects of endotoxin. On the basis of our findings, we concluded that endotoxemia causes cecal and proximal colonic ileus and cecal hypoperfusion via a mechanism that involves α2 adrenergic receptors.

Free access
in American Journal of Veterinary Research

SUMMARY

Changes in lateral cecal arterial blood flow, mean internal carotid arterial pressure, and heart rate caused by nasogastric administration of fenoldopam (3, 6, and 9 mg/kg of body weight), a selective agonist of dopaminergic receptors, were recorded in 7 healthy horses. Cecal arterial blood flow was significantly increased within 30 minutes after administration of fenoldopam at all 3 dosages, with the peak increases from baseline (67.8 ± 17.5 ml/min) being 125 ± 28, 120 ± 22, and 153 ± 32 ml/min for 3, 6, and 9 mg/kg, respectively. Although carotid arterial pressure did not change significantly after administration of fenoldopam at the dosage of 3 mg/kg, administration of fenoldopam at the dosages of 6 and 9 mg/kg significantly reduced carotid arterial pressure from 113 ± 10 to 88 ± 3 and 81 ± 5 mm of Hg, respectively. Intravenous infusion of metoclopramide, a dopaminergic receptor antagonist, at the rate of 0.125 mg/kg/h, blocked the effect of fenoldopam on cecal arterial blood flow and carotid arterial pressure. It was concluded that dopaminergic receptors mediate alterations in local blood flow and systemic pressure in horses.

Free access
in American Journal of Veterinary Research
in Journal of the American Veterinary Medical Association

Summary

A study was performed to determine prevalence of tumor necrosis factor (tnf) activity in serum of equine neonates with presumed sepsis and to determine correlation between serum tnf activity and severity and outcome of disease. Twenty foals <21 days old were considered suitable for inclusion in this study by satisfying clinical and laboratory criteria suggestive of septicemia. At admission, blood samples were collected from all foals for determination of serum tnf activity, then clinical course and outcome of disease were recorded. Thirty-one clinically normal foals <21 days old served as controls for serum tnf activity. Serum tnf activity was estimated by use of an in vitro cytotoxicity bioassay and WEHI 164 clone-13 murine fibrosarcoma cells. Of the 20 foals with presumed sepsis, 5 had high serum TNF activity. Mean heart rate (P < 0.005), mucosal petechial hemorrhages (P = 0.06), and death rate (P = 0.06) were greater in the group of foals with high serum TNF activity. These foals also had a lower mean neutrophil count (P < 0.001), greater band-to-segmented neutrophil ratio (P < 0.0001), and more prevalent neutrophil toxic changes (P = 0.07) than did foals without serum tnf activity (P = 0.02). Joint swelling was more prevalent in foals without serum tnf activity. Results of the study indicate that serum tnf activity is correlated with clinical criteria of sepsis in equine neonates. An association was apparent between disease severity and serum tnf activity in this group of foals with presumed septicemia.

Free access
in Journal of the American Veterinary Medical Association

Summary

Endotoxin-activated monocytes express a thromboplastin-like procoagulant activity on the cell surface that may serve as a focal point for formation of microvascular thrombi. Because coagulopathy is a common sequela to endotoxemia in the equine species, we investigated the ability of monocytes, isolated from horses with colic, to express procoagulant activity. On the day of admission, and on the third and fifth day of hospitalization, monocytes were isolated from 30 adult horses with colic. A coagulation profile, including prothrombin time, activated partial thromboplastin time, thrombin time, and plasma fibrinogen and serum fibrin degradation products concentrations, was determined at each sample collection. The concentration of endotoxin in the plasma was quantitated at the time of admission. Ten clinically normal adult horses served as controls.

The procoagulant activity of monocytes isolated from horses with colic was significantly (P < 0.05) greater than that of the monocytes isolated from clinically normal horses. On the first and third day of hospitalization, the mean prothrombin time was significantly (P < 0.05) longer in horses with colic, compared with clinically normal horses, and was the most common abnormality in the coagulation profile on the day of admission (25/30; 83%). Mean fibrin degradation products concentration was significantly (P < 0.05) greater in horses with colic on the day of admission and was the second most common abnormality in the coagulation profile on day 1 (23/30; 77%). In horses with colic, the mean prothrombin and activated partial thromboplastin times were significantly (P < 0.05) longer in horses that did not survive, compared with horses that survived. Of the 30 horses with colic, 9 had detectable endotoxin in the plasma at the time of admission. The presence of endotoxin in the plasma was useful in predicting survival in horses with colic; all horses with plasma endotoxin concentration ≥ 10 pg/ml (6/6) did not survive.

Free access
in Journal of the American Veterinary Medical Association

Abstract

OBJECTIVE

Advancements in artificial intelligence (AI) and large language models have rapidly generated new possibilities for education and knowledge dissemination in various domains. Currently, our understanding of the knowledge of these models, such as ChatGPT, in the medical and veterinary sciences is in its nascent stage. Educators are faced with an urgent need to better understand these models in order to unleash student potential, promote responsible use, and align AI models with educational goals and learning objectives. The objectives of this study were to evaluate the knowledge level and consistency of responses of 2 platforms of ChatGPT, namely GPT-3.5 and GPT-4.0.

SAMPLE

A total of 495 multiple-choice and true/false questions from 15 courses used in the assessment of third-year veterinary students at a single veterinary institution were included in this study.

METHODS

The questions were manually entered 3 times into each platform, and answers were recorded. These answers were then compared against those provided by the faculty members coordinating the courses.

RESULTS

GPT-3.5 achieved an overall performance score of 55%, whereas GPT-4.0 had a significantly (P < .05) greater performance score of 77%. Importantly, the performance scores of both platforms were significantly (P < .05) below that of the veterinary students (86%).

CLINICAL RELEVANCE

Findings of this study suggested that veterinary educators and veterinary students retrieving information from these AI-based platforms should do so with caution.

Open access
in Journal of the American Veterinary Medical Association

SUMMARY

Objective

To evaluate the effect of pentoxifylline on response of horses to in vivo challenge exposure with endotoxin.

Animals

24 healthy horses in 3 treatment groups: pentoxifylline, endotoxin, or endotoxin and pentoxifylline.

Procedure

Horses of the pentoxifylline group were given a bolus of pentoxifylline (7.5 mg/kg of body weight, IV), followed by an infusion (3 mg/kg/h) over 3 hours, and those of the endotoxin group were given 20 ng of endotoxin/kg IV over 30 minutes. Those of the combination group were given both of the aforementioned compounds; pentoxifylline was administered immediately after endotoxin. Clinical (rectal temperature, heart and respiratory rates, blood pressure) and hematologic (WBC count; whole blood recalcification time; plasma fibrinogen, thromboxane B2, and 6-keto-prostaglandin F, concentrations; plasma plasminogen activator inhibitor activity; and serum tumor necrosis factor and interleukin 6 activities) variables were evaluated over 24 hours.

Results

Compared with baseline values, there were no significant changes in any variable over time in the horses receiving only pentoxifylline, with the exception of a significant increase in WBC count. Rectal temperature, heart rate, mean blood pressure, WBC count, whole blood recalcification time, fibrinogen concentration, plasminogen activator inhibitor activity, tumor necrosis factor and interleukin 6 activities, and plasma thromboxane B2 concentration changed significantly over time in horses of the endotoxin and endotoxin-pentoxifylline combination groups. Respiratory rate and plasma 6-keto-prostaglandin F concentration changed significantly over time only in horses of the endotoxin group. Compared with values for the endotoxin group, rectal temperature and respiratory rate were significantly lower, and whole blood recalcification time was longer for the endotoxin/pentoxifylline group.

Conclusion

Beneficial effects of pentoxifylline are limited when it is administered IV to horses after in vivo challenge exposure with endotoxin. (Am J Vet Res 1997;58:1300–1307)

Free access
in American Journal of Veterinary Research

Summary

Vascular patterns to thoracic limbs, thorax, and neck muscles were studied in 10 dogs (20 limbs) to identify muscles most suitable for transposition in the treatment of large wounds. Gross dissection of injected specimens and angiography were used to identify vascular pedicles. Size and location of pedicles were generally consistent, and any variations would not interfere with most muscle transfers. The cutaneous trunci, latissimus dorsi, sternothyroideus, sternohyoideus, deep pectoral, anconeus, ulnaris lateralis, and ulnar head of flexor carpi ulnaris muscles were identified as suitable for transfer. The cranial trapezius, caudal omotransversarius, cleidobrachialis, and caudal sternocephalicus muscles also had potential for use. Other muscles, because of inaccessibility or unfavorable vascular pattern, were not suitable candidates for transfer.

Free access
in American Journal of Veterinary Research

SUMMARY

Over a 24-month period, serum tumor necrosis factor (tnf) activity was determined in 289 horses with colic attributable to gastrointestinal tract disease. Serum tnf activity was quantitated by use of a modified in vitro cytotoxicity bioassay, using WEHI 164 clone-13 murine fibrosarcoma cells. Causes for colic, determined by clinical and laboratory evaluation, exploratory celiotomy, or necropsy included: gastrointestinal tract rupture (gtr); ileal impaction; small intestinal strangulating obstruction (sio); proximal enteritis (pe); transient small intestinal distention; large-colon displacement; large-colon vovulus; large-colon impaction; colitis; small-colon obstruction; peritonitis; and unknown. Each diagnosis was placed into 1 of 3 lesion categories: inflammatory disorders (gtr, pe, colitis, peritonitis); strangulating intestinal obstruction (sio, large-colon volvulus); and nonstrangulating intestinal obstruction (ileal impaction, transient small intestinal distension, large-colon displacement, large-colon impaction, small-colon obstruction, unknown). The prevalence of high serum tnf activity and/or mortality were evaluated. Differences were tested at significance level of P < 0.05.

Approximately 20% of the 289 horses has serum tnf activity greater than that found in clinically normal horses (> 2.5 U/ml). Twenty-three horses (8%) had marked increase in serum tnf activity (≥ 10 U/ml) which was more prevalent among horses with sio and pe than in horses of other diagnostic groups, except those with gtr. Mortality and marked increase in serum tnf activity were greater in horses with intestinal inflammatory disorders or strangulating intestinal obstruction than in horses with nonstrangulating intestinal obstruction. Similarly, a greater proportion of the horses that died had markedly high serum tnf activity than did horses that lived. Mortality of horses with serum tnf ≥ 10 U/ml was greater than that of horses with serum tnf activity < 10 U/ml. Results indicate possible association between colic and serum tnf activity in horses and that high mortality may be associated with horses with markedly increased serum tnf activity.

Free access
in American Journal of Veterinary Research

Summary

A chronic model with an ultrasonic transit time blood flow probe and strain gauge force transducers implanted on the cecum was used to evaluate cecal mechanical activity and cecal arterial blood flow in 4 conscious adult horses. Intravenous administration of xylazine (1.1 mg/kg of body weight) significantly decreased heart rate and cardiac output, but significantly increased diastolic pulmonary arterial pressure, mean pulmonary arterial pressure, carotid arterial pressure, and central venous pressure. Lateral cecal arterial blood flow after xylazine administration was decreased substantially more than was cardiac output, suggesting that xylazine caused constriction of the cecal vasculature. This effect of xylazine may have resulted from either a direct effect of xylazine on the cecal vasculature or from reflex vasoconstriction attributable to reduced cardiac output. Intravenous administration of butorphanol tartrate (0.1 mg/kg) did not significantly alter the hemodynamic responses to xylazine. Cecal mechanical activity, as measured by the motility index, was decreased for 120 minutes after administration of xylazine and for 150 minutes after administration of xylazine/butorphanol.

Free access
in American Journal of Veterinary Research