Equine veterinary journal. Supplement最新文献

Reasons for performing study: There are no refereed controlled documentations of the skeletal analgesic efficacy of different dosages of flunixin meglumine (FM).

Objectives: The objective of this experiment was to compare the efficacy of various dosages of FM with a negative control. The hypothesis was that higher doses would result in improved efficacy in a dose-dependent manner when tested in a reversible model of foot lameness.

Methods: Ten horses shod with adjustable heart bar shoes had weekly modified AAEP grade 4.0/5.0 lameness induced by tightening a set screw against the heart bar. Heart rate (HR) and lameness score (LS) were monitored by one double-blinded investigator at rest; every 20 min after lameness induction for 5 h and hourly for another 8 h. One hour after lameness induction, treatments were administered i.v. in a randomised order: negative control (isotonic saline: SAL) or FM at 0.55 (half-dose), 1.1 (single-dose) or 2.2 (double-dose) mg/kg bwt. Results were compared using RM ANOVA and Student-Newman-Keul's test with the level of significance set at P < 0.05.

Results: Compared to SAL, half-dose FM reduced HR at 2.33, 2.67, 4.0-8.0, and 10.0 h and LS at 1.33-12.0 h (P < 0.05). Single- and double-dose FM reduced HR from 0.67 to 12.0 h and LS from 1.0 to 12.0 h post administration (P < 0.05). Compared with half-dose FM, single- and double-dose LS were further decreased from 1.67 to 12.0 h post administration (P < 0.05). Mean peak and decaying plasma FM concentrations were different between dosages in a dose-dependent manner through 6 h post administration (P < 0.05).

Conclusions: Flunixin meglumine administration affected dependent variables in a dose-dependent manner with half-dose FM clinically effective for a shorter period. Higher dosages did not perform differently from one another.

Potential relevance: Practitioners must be aware that half-doses of FM are less efficacious than single doses but double doses are not more efficacious and yet are potentially more toxic.

Reasons for performing study: Exposure of horses to airborne particulates during stable confinement has been linked with airway inflammation in these animals. Understanding that link requires accurate measures of exposures and greater understanding of the sources of variability in these exposures.

Objectives: Area and breathing zone particulate concentrations were measured over time in order to determine the relative variability introduced by daily, monthly or between horse variations. Additionally, the relationship between area and breathing zone respirable particulate concentrations was examined.

Methods: The study was conducted in a Thoroughbred training stable. Breathing zone and area respirable particulate concentrations were measured over a 30-month period. Mixed-model analysis of variance was used to determine effect of month and year at the time of sampling and the daily variance upon area particulate concentrations. The effects of hay feeding method and horse variance on breathing zone measures were included in the model. Real-time concentrations of particulate matter with an aerodynamic diameter of 10 microm or smaller (PM10) were measured to determine the effect of barn door position. Significance was set at P < 0.05.

Results: Average area particulate concentration varied with month and year of sampling but daily variation was not significant. Maximum area respirable particulate concentrations were significantly affected by daily variation. Opening barn doors resulted in lower PM10 levels. Horses fed from hay nets were exposed to significantly higher concentrations of respirable particulates in their breathing zone than when fed hay on the ground. Horse-to-horse variability was significant. Breathing zone concentrations were significantly greater than area concentrations and the 2 measurements were not correlated.

Conclusions: While area respirable particulate concentrations reflected seasonal changes, these measures are poor predictors of individual horse exposure. Instead, methods of feeding and individual horse behaviour are important determinants of exposure.

Potential relevance: Studies investigating the effect of natural exposures on lung health in horses should consider the effects of individual behaviour and management practices on breathing zone exposure.

Reasons for performing study: Knowledge of commonly encountered fungi infecting the mare's reproductive tract and their respective drug susceptibilities should improve treatment efficacy in mares with fungal endometritis. This is particularly important when practitioners need to start empiric treatment before culture results are complete.

Objective: To report the spectrum of fungal isolates from uterine samples from mares with reproductive problems and their respective antifungal susceptibilities.

Methods: Equine uterine samples submitted to the Cornell University Animal Health Diagnostic Centre for fungal culture between July 1999 and June 2011 were reviewed. Each mare's reproductive history, fungal culture results, antifungal susceptibilities and concurrent aerobic culture results were evaluated. Patterns of antifungal susceptibility and resistance were assessed over time.

Results: One hundred and two fungal isolates were cultured from 92 uterine samples from mares with reproductive problems. Yeast (69%) and mould with septated hyphae (26%) were the most common isolates. Ninety-five to 100% of all fungal isolates were susceptible to the polyenes, while response to the azoles varied with 47-81% of fungal isolates displaying susceptibility. Yeast isolates were 100% susceptible to the polyenes and least susceptible to miconazole (48%) while isolates of mould with septated hyphae were most susceptible to natamycin (100%) and least susceptible to fluconazole (0%). From July 1999 to June 2005 and July 2005 to June 2011, yeast demonstrated increasing resistance to miconazole, while mould with septated hyphae demonstrated increasing resistance to ketoconazole.

Conclusions and clinical relevance: Results from this study suggest that polyenes are effective against uterine fungal isolates in vitro and may be the empiric treatment of choice for fungal endometritis. Isolate resistance to specific azoles increased over time.

Reasons for performing study: Increasing evidence suggests that reactions to lipopolysaccharide (LPS), particularly in the gut, can be partly or completely mitigated by colostrum- and milk-derived oligosaccharides. Confirmation of this hypothesis could lead to the development of new therapeutic concepts.

Objectives: To demonstrate the influence of equine colostral carbohydrates on the inflammatory response in an in vitro model with equine peripheral blood mononuclear cells (PBMCs).

Methods: Carbohydrates were extracted from mare colostrum, and then evaluated for their influence on LPS-induced inflammatory responses in PBMCs isolated from the same mares, mRNA expression of tumour necrosis factor-alpha, interleukin-6 and interleukin-10 was measured as well as the protein levels of tumour necrosis factor-alpha (TNF-alpha) and interleukin-10 (IL-10).

Results: Equine colostral carbohydrates significantly reduced LPS-induced TNF-alpha protein at both times measured and significantly reduced LPS-induced TNF-alpha, IL-6 and IL-10 mRNA expression by PBMCs. Moreover, cell viability significantly increased in the presence of high concentrations of colostral carbohydrates.

Conclusions: Carbohydrates derived from equine colostrum reduce LPS-induced inflammatory responses of equine PBMCs.

Potential relevance: Colostrum and milk-derived carbohydrates are promising candidates for new concepts in preventive and regenerative medicine.

Reasons for performing study: Application of the lactose (13) C-ureide breath test (LUBT) for measurement of equine orocaecal transit time (OCTT) has not been reported previously. The ability to assess OCTT noninvasively, and to investigate its relationship to gastric emptying rate and small intestinal transit, would be of both clinical and research value.

Objectives: 1) Assessment of the LUBT in healthy horses, with comparison of induced versus noninduced test protocols. 2) Application of a new dual stable isotope breath test (lactose (13) C-ureide and (13) C-octanoic acid) for gastrointestinal transit measurement.

Hypothesis: The LUBT will allow quantification of equine OCTT, and test efficacy will be enhanced by prior administration of lactose (12) C-ureide as shown in vitro. The dual tracer breath test will permit simultaneous measurement of gastric emptying, OCTT and small bowel transit times.

Methods: Induced and noninduced LUBTs were performed in 3 healthy mature horses in randomised order using a standard test meal and protocol. Combined LUBT and (13) C-octanoic acid breath tests ((13) C-OABT) were performed in 4 individuals on 4 occasions at weekly intervals. Expiratory isotopic recovery was modelled to allow generation of gastric emptying data, small bowel transit times and caecal transit parameters.

Results: The induction protocol for the LUBT increased the rate and magnitude of expiratory (13) CO(2) significantly. Mean ± s.d. values for OCTT, caecal lag phase (t(lag) ) and caecal t(1/2) using the induced LUBT were 3.24 ± 0.65 h, 5.62 ± 1.22 h and 6.31 ± 1.21 h, respectively. Dual stable isotope tests resulted in the production of 2 discrete peaks in expiratory (13) CO(2) in 15/16 tests from which gastric t(1/2), OCTT and small bowel transit (SBT) parameters could be calculated.

Conclusions: The induced LUBT provides a reliable noninvasive measure of equine OCTT and can be paired with the (13) C-OABT to provide further information about small intestinal motility.

Reasons for performing study: Validation of a reliable, noninvasive clinical test for quantification of equine orocaecal transit time (OCTT) is required. This would facilitate an evidence-based approach to investigation and treatment of equine small intestinal disorders.

Objectives: 1) Comparison of the lactose (13) C-ureide breath test (LUBT) with the hydrogen breath test (H(2) BT) for OCTT measurement. 2) Identification of the characteristics of gastrointestinal microbial glycosylureide hydrolase activity in vitro. 3) Production of an optimised protocol for the LUBT for in vivo measurement of equine OCTT.

Hypothesis: Significant lactose (13) C-ureide ((13) C-LU) hydrolase activity is restricted to the large bowel. The rate of expiratory (13) CO(2) production after ingestion of the isotope will provide an indirect quantifiable measure of orocaecal transit rate. Requisite bacterial activity may be enhanced by a primer dose of unlabelled substrate as shown in Man.

Methods: Combined LUBT and H(2) BT were performed in 8 healthy individuals. Analysis of sequential end expiratory breath samples was used to calculate OCTT and results compared. Digestion of (13) C-LU was investigated in vitro using fresh faecal material or intestinal aliquots collected post mortem. Isotopic fermentation rate was measured by rate of appearance of (13) CO(2) .

Results: Peaks in expiratory (13) CO(2) occurred in all individuals after ingestion of the labelled test meal, whereas H(2) expiration was variable. Both faecal and intestinal microbial digestion of (13) C-LU were maximised by prior exposure to (12) C-LU. Induced bacterial glucoseureide hydrolase activity was significantly greater in the caecum than in the small intestine (n = 10, P<0.05).

Conclusions: Significant (13) C-LU digestion is restricted to the equine large intestine under normal conditions, and is enhanced by prior exposure to (12) C-LU, making (13) C-LU a suitable noninvasive marker of equine OCTT. The LUBT is more reliable than the H(2) BT for measurement of equine OCTT.

Reasons for performing study: Flunixin meglumine is used for treatment of equine colic despite evidence of inhibited recovery of mucosal barrier function following small intestinal ischaemic injury. This study aimed to characterise an alternative treatment (AHI-805) for abdominal pain in the horse.

Objective: To determine the effect of AHI-805, an aza-thia-benzoazulene derivative, on the cyclooxygenase enzymes and the recovery of mucosal barrier function following ischaemic injury.

Methods: Effect of AHI-805 on in vitro COX-1 and COX-2 activity was determined by measuring coagulation-induced thromboxane B(2) (TXB(2)) and lipopolysaccharide-stimulated prostaglandin E(2) concentrations in equine whole blood. Horses (n = 6) were anaesthetised and jejunum subjected to ischaemia for 2 h. Control and ischaemia injured mucosa was placed in Ussing chambers and treated with Ringer's solution containing control treatment (DMSO), flunixin meglumine (27 µmol/l), or AHI-805 (27 µmol/l). Transepithelial electrical resistance (TER), mucosal-to-serosal flux of (3) H-mannitol, and bathing solution TXB(2) and prostaglandin E metabolites (PGEM) were measured over a 4 h recovery period.

Results: Treatment with AHI-805 had no significant effect on TXB(2) production but significantly inhibited production of PGE(2) at a concentration of 1 µmol/l or greater. TER of flunixin or AHI-805 treated ischaemia-injured jejunum was significantly lower than control treated injured tissue over the recovery period. Mannitol flux and grade of histological damage were significantly increased by ischaemic injury only. There was a significant increase in PGEM and TXB(2) in control tissues over the 240 min recovery period, but not in flunixin or AHI-805 treated tissues.

Conclusions: Flunixin meglumine and AHI-805 inhibit recovery of barrier function in ischaemic-injured equine jejunum in vitro through inhibition of the COX enzymes.

Potential relevance: The novel compound AHI-805 may not be suitable for the treatment of equine colic associated with ischaemic injury.

Reasons for performing study: N-butylscopolammonium bromide (NBB) and xylazine are commonly used medications for the treatment of spasmodic colic and other forms of abdominal pain in horses. Both NBB and xylazine exert significant effects on the cardiovascular system and other vital systems of horses.

Objective: To evaluate the effects of i.v. administration of NBB, xylazine, and the combination of NBB and xylazine on heart rate, other commonly measured physiological parameters, cardiac rhythm and blood pressure.

Methods: Six mature horses of mixed breed were used. In a random cross-over design, each horse was given 0.3 mg/kg bwt of NBB i.v., 0.25 mg/kg bwt xylazine i.v., and a combination of 0.3 mg/kg bwt NBB and 0.25 mg/kg bwt xylazine. Heart rate, physiological parameters, cardiac rhythm and indirect blood pressure were recorded at timed intervals before and 60 min following administration.

Results: Heart rate and blood pressure were significantly elevated immediately following administration of NBB or NBB with xylazine. Administration of NBB with xylazine resulted in significantly greater initial and peak blood pressure values than with NBB alone. Administration of xylazine resulted in a decrease in heart rate, with an initial increase in blood pressure followed by a decrease in blood pressure. Sinus tachycardia was seen with NBB, and NBB and xylazine administration. First and second degree atrioventricular block was identified with xylazine administration. Ventricular tachycardia was identified in one horse following NBB and xylazine administration.

Conclusions: Results of this study suggest that the effects of administration of NBB alone or in combination with xylazine to horses with colic, especially to those with systemic cardiovascular compromise, should be considered carefully to assess condition and predict prognosis accurately, and to avoid potential adverse effects.

Reasons for performing study: The generation and maintenance of intestinal motility patterns involve the complex interactions of several components including the gastrointestinal pacemaker cells (interstitial cells of Cajal, ICC). Central to ICC function is the generation of rhythmic pacemaker currents, namely slow waves, which represent the rate limiting step for intestinal smooth muscle contractions. Currently, intracellular slow wave activity has not been demonstrated in the equine colon.

Objectives: To characterise the in vitro myoelectrical activity of the equine pelvic flexure using intracellular recording techniques.

Methods: Intestinal samples were collected immediately following euthanasia from 14 normal horses. One millimetre thick tissue sections were pinned and superfused with warmed, oxygenated Krebs solution. Intracellular recordings were made from smooth muscle cells close to the submucosal border of the circular muscle layer. The L-type Ca(2+) channel blocker nifedipine was added to the superfusion fluid in 9 experiments while the Na(+) channel blocker tetrodotoxin was added to the superfusion fluid in 4 experiments. The data were recorded and stored using an acquisition system and a software package used to analyse the recordings.

Results: In 10 of the 14 horses, electrical events consistent with slow wave patterns were recorded from individual smooth muscle cells. Surprisingly, adding nifedipine to the superfusion fluid abolished all electrical activity. In contrast, tetrodotoxin had no apparent effect on the electrical activity.

Conclusions: Assuming that the electrical events were slow waves, the blockade by nifedipine suggests significant and potentially important differences in the ionic mechanisms responsible for slow waves in the different regions of the equine intestinal tract, which deserve further evaluation.

Reasons for performing study: Repair of incisional hernias in horses has been described previously; however, this report describes the outcome of primary closure of incisional hernias in a large number of horses and compares these results with those of mesh implantation.

Objective: To report the perioperative care, complications and long-term outcome of primary closure of incisional hernias in horses and to compare these results with a second population of horses in which prosthetic mesh was used.

Methods: Medical records of horses undergoing an incisional herniorrhaphy between 1998 and 2009 were reviewed. Information obtained included case details, factors from the initial surgery that contributed to the hernia formation, method of hernia repair and outcome. Comparisons between horses with and without mesh were made using logistic regression.

Results: Thirty-eight horses with primary closure and 9 horses with mesh implantation met inclusion criteria. Long-term follow-up for cases in which a mesh was not used was available for 25 cases; of these, 21 horses (84%) had a normal cosmetic appearance and 4 (16%) had a visible defect. There was no significant difference between the 2 repair methods in terms of age, sex, breed, weight, size of the hernia, number of defects, timing of the repair or cosmetic outcome. Horses in which a mesh was used had significantly longer duration of surgery and hospitalisation, and were significantly more likely to develop post operative complications while having a longer duration of convalescence prior to return to use.

Conclusions: Primary apposition of incisional hernias in horses without the use of mesh support appears to result in a good cosmetic outcome while avoiding the complications associated with mesh implantation in this population of horses.

Potential relevance: Surgical time, duration of hospitalisation, and post operative complications may be reduced by using this technique of primary repair and avoiding mesh implantation.