bluuebunny/crossref_metadata_2025 huggingface dataset:
Specificity and reversibility of the training effects on the concentration of Na+, K+‐ATPase in foal skeletal muscle
Authors: SUWANNACHOT P. , VERKLEIJ C. B. , KOCSIS S. , VAN WEEREN P. R. , EVERTS M. E.
Published: April 2007

The purpose of the present study was to determine whether training and detraining affect the Na+, K+‐ATPase concentration in horse skeletal muscles, and whether these effects are specific for the muscles involved in the training programme. Twenty‐four Dutch Warmblood foals age 7 days were assigned randomly to 3 groups: Box (box‐rest without training), Training (box‐rest with training: short‐sprint) and Pasture (pasture without training). Exercise regimens were carried out for 5 months and were followed by 6 months of detraining. Five of the foals in each group were subjected to euthanasia at age 5 months and the remaining foals at 11 months. Muscle samples were collected from the deep part of thegluteus medius, semitendinosusand masseter muscles. The Na+, K+‐ATPase concentration was quantified by [3H]ouabain binding.

In the Training group, the concentration of Na+, K+‐ATPase ingluteus mediusandsemitendinosusmuscle, but not in masseter muscle, showed a relative increase of 20% (P<0.05) as compared to Box foals. After detraining for the subsequent 6 months, the concentration of Na+, K+‐ATPase insemitendinosusmuscle remained the same, while that ingluteus mediusmuscle was reduced by 10%.

It is concluded that: 1) short‐sprint training for 5 months induced an increase of the Na+, K+‐ATPase concentration ingluteus mediusandsemitendinosusmuscles of the foal. Interestingly, this effect persisted during the 6 months of the detraining period. Whether the higher Na+, K+‐ATPase concentration due to training of young foals leads to a better athletic performance when they become mature still needs to be established; 2) the factors that initiate an increase in Na+, K+‐ATPase concentration following training are likely to be located in the muscle itself and 3) the training effect may last for several months after returning to normal activity, especially in muscles containing a high percentage of fast‐twitch fibres.
Effects of inhalation of albuterol sulphate, ipratroprium bromide and frusemide on breathing mechanics and gas exchange in healthy exercising horses
Authors: BAYLY W. M. , SLOCOMBE R. F. , SCHOTT H. C. , HINES M. T. , SIDES R. H. , HAKALA J. E.
Published: April 2007

The possibility that pre‐exercise inhalation of a bronchodilator by healthy horses could improve their mechanics of breathing and enhance performance was investigated. Ipratropium bromide (0.35 μg/kg bwt; n = 7) was administered by nebulisation 30 min before exercise and frusemide (1 mg/kg bwt; n = 6) was given in the same manner 2 h before exercise. Albuterol sulphate (360 and 720 μg; n = 7) were administered with a metered dose inhaler 2 h before exercise. Each drug was investigated independently of the others using cross‐over protocols. Horses completed incremental exercise tests and oxygen consumption, carbon dioxide production, arterial blood gases, heart rate and measures of breathing mechanics including total pulmonary resistance (RL) and nasopharyngeal resistance (RU) were determined for each exercise intensity. The resistance of the lower airways was calculated subsequently from the difference between RLand RU. None of the drugs tested had an effect on any of the variables measured, possibly because maximal bronchodilation is stimulated in healthy horses by the normal sympathoadrenergic response to exercise. Therefore, the pre‐exercise inhalation of a bronchodilator by a healthy horse is unlikely to improve performance capacity.
A case‐control study of respiratory disease in Thoroughbred racehorses in Sydney, Australia
Authors: CHRISTLEY R. M. , HODGSON D. R. , ROSE R. J. , WOOD J. L. N. , REID S. W. J. , WHITEAR K. G. , HODGSON J. L.
Published: April 2007

In order to investigate the role of infectious agents in the aetiology of lower respiratory tract disease in Thoroughbred racehorses, a matched case‐control study was conducted. Cases were identified by the presence of coughing, and were compared to a control population matched on time of sample collection and location within the same training establishment. Tracheal wash samples were collected from 100 cases and 148 controls. Case horses were more likely than controls to have endoscopic and cytological evidence of airway inflammation. There was no significant association between serological evidence of infection by commonly implicated respiratory viruses and coughing. Similarly, mycoplasma were rarely isolated and were not associated with disease. In contrast, there was a strong association between isolation of greater than a total of 103colony‐forming units/ml of tracheal wash and coughing. Individual bacterial species associated with disease includedStreptococcus zooepidemicus, Streptococcus pneumoniae, Streptococcus suis, Streptococcus sanguis, Pasteurellaspp andBordetella bronchiseptica.This study provides evidence of the role of bacterial infection in the aetiology of lower respiratory tract inflammation in racehorses. However, in 58% of cases, few or no bacteria were isolated. Hence, at the time of identification of disease, there was no evidence of viral, bacterial or mycoplasmal infection in the majority of coughing horses. The aetiology of the signs observed in these horses requires further investigation.
Laryngeal paralysis: a study of 375 cases in a mixed‐breed population of horses
Authors: DIXON P. M. , MCGORUM B. C. , RAILTON D. I. , HAWE C. , TREMAINE W. H. , PICKLES K. , MCCANN J.
Published: April 2007

Referred cases (n = 375) of laryngeal paralysis (1985–1998) from a mixed‐breed equine population included 351 (94%) cases of recurrent laryngeal neuropathy (RLN) (idiopathic laryngeal hemiplegia) and 24 cases (6%) of laryngeal paralysis from causes other than RLN. Laryngeal movements were classified endoscopically into one of 6 grades, in contrast to the usual 4 grades. The RLN cases had a mediangrade 4laryngeal paralysis, of which 96% were left‐sided, 2% right‐sided and 2% bilaterally affected. RLN cases included 204 (58%) Thoroughbred, 96 (27%) Thoroughbred‐cross, 23 (7%) draught, 16 (5%) Warmbloods and 10 (3%) other breeds, including only 4 (1%) ponies. The median age of RLN cases at referral was 6 years (range 2–12) and their median height was 170.2 cm. The work of RLN horses included National Hunt racing (42%), flat racing (1%), hunting (19%), eventing (16%) and miscellaneous work (22%). Reported presenting signs in RLN‐affected horses included abnormal exercise‐related respiratory sounds in 90% and reduced exercise tolerance in only 64%. However, many horses were referred before their exercise tolerance could be fully assessed. Forty percent of the RLN cases had intercurrent disorders, including 10% with additional upper respiratory and 7% with lower respiratory tract diseases. The 24 nonidiopathic RLN cases included 12 with bilateral laryngeal paralysis, 11 (92%) of which were ponies. Bilateral laryngeal paralysis occurred with hepatic encephalopathy in 7 cases and following general anaesthesia in 2 cases. The 12 cases of acquired unilateral laryngeal paralysis included 7 caused by guttural pouch mycosis.
Racehorse injuries, clinical problems and fatalities recorded on British racecourses from flat racing and National Hunt racing during 1996, 1997 and 1998
Authors: WILLIAMS R. B. , HARKINS L. S. , HAMMOND C. J. , WOOD J. L. N.
Published: April 2007

For improvements to the safety and welfare of racehorses to be possible, it is essential to have access to basic descriptive information about the veterinary incidents encountered during horseracing. A 3 year surveillance study (1996–1998) was conducted by The Jockey Club into racing injuries, other postrace clinical problems and fatalities from all 59 British racecourses (mainland Britain only) to identify risk factors. During the survey there were 222,993 racing starts: 106,897 starts in flat races on turf (47.9%), 26,519 starts in flat races on all‐weather surfaces (11.9%), 30,932 starts in chases on turf (13.9%), 51,786 starts in hurdle races on turf (23.2%) and 6,859 starts in National Hunt flat races (3.1%). Information was recorded about age of horses, racing surfaces and clinical events observed or attended by a veterinary team of 2 clinicians and one veterinary surgeon employed by the racing authority. Of the 2358 clinical events re ported (1.05% of all starts), 1937 involved the musculoskeletal system and 421 involved other body systems. Six hundred and fifty‐seven incidents (0.29% of starts) resulted in death or euthanasia. Eighty‐one percent of limb injury reports involved forelimbs and 46% involved flexor tendons/suspensory ligaments. Nonlimb problems included epistaxis (0.83/1000 starts), ‘exhausted horse syndrome’ (0.47/1000 starts) and paroxysmal atrial fibrillation (0.20/1000 starts). Incidents including fatalities per 1000 starts were 24.7 from chases, 19.45 from hurdle races, 8.46 from National Hunt flat races and 3.97 from flat races. The overall tendon injury was higher in chases than in hurdle races, even though age‐specific rates of tendon injury were higher in hurdle races than in chases. The risk of injuries per start increased significantly with age, while softer racing surfaces were associated with fewer fatalities and injuries than firmer surfaces. The survey described in this paperhas provided an up‐to‐date description of the fatal and non‐fatal horseracing incidents under conditions on mainland Britain, enabling progress to be made towards improving the safety and welfare of racehorses.
The distribution of intratubular dentine in equine incisors: a scanning electron microscopic study
Authors: MUYLLE S. , SIMOENS P. , LAUWERS H.
Published: April 2007

The distribution of intratubular (peritubular) dentine was studied by scanning electron microscopy in 12 equine incisor teeth. High levels of intratubular dentine were found in the peripheral regions of the dentine. In these areas, a marked asymmetry occurred, as intratubular dentine was predominantly deposited onto the side of the dentinal tubular walls nearest to the dentino‐enamel junction. The quantity and asymmetry of intratubular dentine were reduced towards the centre of the tooth.

The significance of these variations in the amount and distribution of intratubular dentine between the different dentinal regions is discussed.
Repeatability of diagnostic ultrasonography in the assessment of the equine superficial digital flexor tendon
Authors: PICKERSGILL C. H. , MARR C. M. , REID S. W. J.
Published: April 2007

A quantitative investigation of the variation that can occur during the course of ultrasonography of the equine superficial digital flexor tendons (SDFT) was undertaken. The aim of this investigation was to use an objective measure, namely the measurement of CSA, to quantify the variability occurring during the course of the ultrasonographic assessment of the equine SDFT. The effects of 3 variables on the CSA measurements were determined. 1) Image acquisition operator (IAc): two different operators undertaking the ultrasonographic examination; 2) image analysis operator (IAn): two different operators undertaking the calculation of CSA values from previously stored images; and 3) analytical equipment (used during CSA measurement) (IEq): the use of 2 different sets of equipment during calculation of CSAvalues.

Tendon cross‐sectional area (CSA) measurements were used as the comparative variable of 3 potential sources: interoperator, during image acquisition; interoperator, during CSA measurement; and intraoperator, when using different analytical equipment.

Two operators obtained transverse ultrasonographic images from the forelimb SDFTs of 16 National Hunt (NH) Thoroughbred (TB) racehorses, each undertaking analysis of their own and the other operator's images. One operator undertook analysis of theirimages using 2 sets of equipment.

There was no statistically significant difference in the results obtained when different operators undertook image acquisition (P>0.05). At all but the most distal level, there was no significant difference when different equipment was used during analysis (P>0.05). A significant difference (P<0.01) was reported when different operators undertook image analysis, one operator consistently returning larger measurements.

Different operators undertaking different stages of an examination can result in significant variability. To reduce confounding during ultrasonographic investigations involving multiple persons, one operator should undertake image analysis, although different operators may undertake image acquisition.
Spectrophotometric assessment of peritoneal fluid haemoglobin in colic horses: an aid to selecting medical vs. surgical treatment
Authors: WEIMANN C. D. , THOEFNER M. B. , JENSEN A. L.
Published: April 2007

In a case‐control study in colic horses the ability of spectrophotometric measurement of the haemoglobin concentration in the peritoneal fluid supernatant and visual assessment of the colour of peritoneal fluid supernatant to differentiate between surgical and medical treatment of colic was assessed. Based on previous studies, which have found and a association between peritoneal fluid colour and the kind of treatment required, our hypothesis was that the peritoneal fluid haemoglobin concentration would be higher in horses requiring surgical intervention than in horses amenable to medical treatment.

Seventy‐four horses admitted to a teaching hospital were included. Thirty‐five horses were classified as requiring surgery and 39 medical treatment. Logistic regression revealed a significant (P<0.0001) association between the haemoglobin concentration measured with the spectrophotometer and the need for surgical treatment. Odds ratio for an increase in haemoglobin concentration of 0.01 mmol/l was 6.4, which means that the odds for ‘need for surgical treatment’ increased when peritoneal fluid haemoglobin concentration increased.

When used as a diagnostic test with a threshold of 0.01 mmol/l haemoglobin for selecting surgical vs. medical treatment, sensitivity was 80% and specificity 82%, whereas simple visual assessment had a sensitivity of only 51% and a specificity of 95%.
Treatment of ischaemic jejunum with topical and intraluminal Carolina Rinse
Authors: YOUNG B. L. , WHITE N. A. , DONALDSON L. L. , DABAREINER R. M.
Published: April 2007

Carolina Rinse Solution (CRS) was applied topically and intraluminally to ischaemic (Group 1; n = 5) and distended equine jejunum (Group 2; n = 5). Mesenteric blood flow, ORC (osmotic reflection coefficient), wet weight to dry weight ratios (WW/DW), serosal thickness, and neutrophil accumulation in the serosa were measured. After 60 min ischaemia followed by reperfusion (Group 1), mesenteric blood flow remained greater than baseline values. The mean ORC was similar to that previously reported in normal bowel or ischaemic intestine treated with CRS by arterial perfusion. The ORC after distention and decompression (Group 2) increased and was similar to that previously reported in a comparable untreated experimental model. The WW/DW after both ischaemia and distention increased compared to specimens collected from noninstrumented jejunum proximal to the experimental segments in the same horses. There was no difference in neutrophil numbers in the serosa of either ischaemic or distended intestine compared to the noninstrumented proximal jejunum. CRS‐treated ischaemic intestine maintained microvascular permeability similar to that reported for normal intestine whereas treated distended intestine did not. Combined topical and intraluminal application of CRS to ischaemic intestine may reduce complications due to acute inflammation during reperfusion.
Ureteral ligation prevents the haemodynamic effect of frusemide in pentobarbitol anaesthetised horses
Authors: HUBBELL J. A. E. , HINCHCLIFF K. W. , GROSENBAUGH D. A. , BEARD W. L. , BEARD L. A.
Published: April 2007

Frusemide reduces pulmonary vascular pressures in resting horses and attenuates exercise‐induced increases in these pressures in exercising horses. The mechanism underlying these effects of frusemide is unclear. We tested the hypothesis that the haemodynamic effects of frusemide are dependent on diuresis by examining the effect of frusemide in anaesthetised horses in which diuresis was prevented by ligation of ureters. Twenty four horses were assigned randomly to one of 4 treatments: 1) frusemide (1 mg/kg bwt i.v.) and intact ureters; 2) frusemide and ligated ureters; 3) saline placebo and ligated ureters; and 4) frusemide and phenylbutazone (4.4 mg/kg bwt i.v. 12 h and 15 min before frusemide) and ligated ureters. Frusemide administration to anaesthetised horses with intact ureters increased plasma total protein concentration and reduced mean right atrial, pulmonary artery and aortic pressures. There was no significant effect of frusemide administration on haemodynamic variables or plasma total protein concentration in horses with ligated ureters. The combination of frusemide and phenylbutazone increased mean right atrial, pulmonary artery and aortic pressures in horses with ligated ureters. This study demonstrates that, in anaesthetised horses, the haemodynamic effect of frusemide is dependent upon diuresis. We interpret these results as providing further evidence that the haemodynamic effect of frusemide in horses is attributable to a reduction in plasma and blood volume.
Effects of cross‐tying horses during 24 h of road transport
Authors: STULL C. L. , RODIEK A. V.
Published: April 2007

Transportation stress has been implicated as a predisposing factor to respiratory disease in horses. Cross‐tying horses individually in stalls is common practice for transporting show and racehorses, but horses also travel in small groups or individually without being restricted by tying. The objective of this study was to compare physiological responses of horses travelling cross‐tied or loose during 24 h of road transport. Ten horses were used in a cross‐over design consisting of two 4 day trials. In the first trial, 6 horses were cross‐tied, while 2 pairs of horses were loose in enclosed compartments. Treatments were reversed in the second trial. Baseline samples were collected on Day 1, horses transported on Day 2, and recovery data collected on Days 3 and 4. Blood samples were collected daily at 0800, 1100 and 2000 h. The mean responses in all horses of serum cortisol, lactate, glucose, α1‐acid glycoprotein, and total protein concentrations, packed cell volume (PCV), white blood cell (WBC) counts and aminotransferase and creatine kinase were was elevated significantly from baseline during the 4 day study. The response of white blood cell counts, neutrophil to lymphocyte ratios and glucose and cortisol concentrations was significantly elevated in the cross‐tied compared to the loose group during transport and recovery. This study supports the recommendation of allowing horses during long‐term transportation to travel loose in small compartments, without elevating their head by cross‐tying.
Factors influencing the development of stereotypic and redirected behaviours in young horses: findings of a four year prospective epidemiological study
Authors: WATERS A. J. , NICOL C. J. , FRENCH N. P.
Published: April 2007

Stereotypies are invariant and repetitive behaviour patterns that seemingly have no function, which tend to develop in captive animals faced with insoluble problems and may be indicative of reduced welfare. A 4 year prospective study of the factors influencing the development of stereotypic and redirected behaviours (abnormal behaviour) in a population of 225 young Thoroughbred and part‐Thoroughbred horses was conducted between 1995 and 1999. Abnormal behaviour affected 34.7% of the population. Multivariable analysis showed that foals of low‐ or middle‐ranking mares were less likely to develop abnormal behaviour than foals of dominant mares (rate ratio (RR) 0.23, P<0.01; RR 0.48, P<0.01, respectively). Weaning by confinement in a stable or barn was associated with an increased rate of development of abnormal behaviour, compared with paddock‐weaning (RR 2.19, P<0.05), and housing in barns, rather than at grass after weaning, was associated with a further increase (RR 2.54, P<0.01). Specific stereotypic and redirected behaviours were then considered as separate outcomes. Cribbiting was initiated by 10.5% of horses at median age 20 weeks, weaving by 4.6% of horses at median age 60 weeks, box‐walking by 2.3% of horses at median age 64 weeks and wood‐chewing by 30.3% of horses at median age 30 weeks. Wood‐chewing developed at a lower rate in horses born to subordinate or mid‐ranking mares than in horses born to dominant mares (RR 0.29, P<0.01; RR 0.41, P<0.01, respectively), and at a higher rate in horses kept in barns or stables rather than at grass after weaning (RR 4.49, P<0.001; RR 1.46, P<0.001, respectively). Feeding concentrates after weaning was associated with a 4‐fold increase in the rate of development of crib‐biting (RR 4.12, P = 0.02). The results of this study support the idea that simple changes in feeding, housing and weaning practices could substantially lower the incidence of abnormal behaviour in young horses.
Comparison of lithium dilution and thermodilution cardiac output measurements in anaesthetised neonatal foals
Authors: CORLEY K. T. T. , DONALDSON L. L. , FURR M. O.
Published: April 2007

Knowledge of cardiac output is expected to help guide the treatment of hypotension associated with critical illness and/or anaesthesia in neonatal foals. However, a practical and safe method of measuring cardiac output has not been described for the foal. Lithum dilution, a new method of cardiac output determination not requiring cardiac catheterisation, has recently been reported in mature horses. We compared this method to thermodilution in isoflurane‐anaesthetised foals age 30–42 h and found good agreement between the 2 methods in a range of cardiac outputs 5.4–20.41/min. The lithium dilution technique is a practical and reliable method of measuring cardiac output in anaesthetised neonatal foals, and warrants investigation in critically ill conscious foals.
Caprine serum fraction immunomodulator as supplemental treatment of lower respiratory disease in the horse
Authors: HAMM D. , WILLEFORD K. O. , WHITE G. , REED S. M. , HAMM J.
Published: April 2007

Suppurative lower airway disease is a common debilitating disease in performance horses and, while rarely fatal, is often recalcitrant to conventional therapy. A variety of treatments have been used to combat this condition and we conducted two types of studies to determine if caprine serum fraction ‐ immunomodulator (CSFI), a nonspecific immunomodulator, improved recovery from lower respiratory disease. Two dose response studies were performed to ascertain the efficacy of CSFI. Horses were maintained daily on conventional antibiotic therapy. Respiratory tract exudate, nasal discharge, dyspnoea, chest auscultation and cough frequency were monitored weekly. One hundred percent of the horses treated with 2 i.m. injections of either 60 or 120 mg CSFI one week apart showed significant improvement with each weekly evaluation and were fully recovered by week 3. Horses treated with 15 or 30 mg CSFI did not differ significantly from the control group. Only 10% of the control horses responded to conventional antibiotic therapy.

An expanded field trial utilising 80 horses diagnosed with lower respiratory disease and housed at 4 equine clinics was conducted. Thirty‐five percent of the 40 control horses, treated solely by conventional antibiotic therapies, recovered while 75% of the horses treated with a supplemental administration of 60 mg CSFI as described above recovered. The combined data from these studies showed that CSFI was able to promote an overall recovery from lower respiratory disease of 86%.
Pharmacokinetic/pharmacodynamic approach to assess irrelevant plasma or urine drug concentrations in postcompetition samples for drug control in the horse
Authors: TOUTAIN P. L. , LASSOURD V.
Published: April 2007

The current performance of analytical techniques used for drug control in horses lead the Regulatory Authorities to decide whether trace levels of drugs legitimately used for therapeutic medication should or should not be reported. Here, we propose a well‐ordered and nonexperimental pharmacokinetic/pharmacodynamic approach for the determination of irrelevant drug plasma (IPC) and urine concentrations (IUC). The published plasma clearance is used to transform an effective (marketed) dose into an effective concentration (EPC). EPC is transformed into an IPC by applying a safety factor (SF). This method is based on several assumptions (e.g. drug effects reversibly driven by plasma concentration, linearity of drug disposition). The suitability of the computed IPC and IUC can be checked by calculating the residual amount of drug at IPC and computing a minimal drug withdrawal time. It is concluded that controlling the drug effect (using drug or any analyte concentration as a marker) rather than the drug exposure will be more demanding and also makes urine a less than ideal matrix.
Parenteral nutrition for horses with gastrointestinal disease: a retrospective study of 79 cases
Authors: LOPES M. A. F. , II N. A. WHITE
Published: April 2007

Parenteral nutrition is advocated for sick foals and horses, although there is no report which has critically evaluated its benefits in this species. Therefore, the hypothesis that parenteral nutrition (PN) is beneficial for horses with severe gastrointestinal disease was investigated in a retrospective study. Records from 79 treatment courses in horses with gastrointestinal disease were reviewed for the years 1992–2000. The fatality rate (48.1%) was attributed to the severity of the primary disease. Complications due to PN were recorded and hyperglycaemia was the most common complication associated with PN. The number of laparatomies, proportion of horses that received lipid emulsion and the daily cost were higher in nonsurvivors than in survivors. The length of PN course was longer in survivors, although glucose peak was observed later in nonsurvivors after initiation of PN. The content of vitamins in PN solution and plasma protein at the beginning of PN were higher for survivors, while the volume of plasma administered was significantly larger in nonsurvivors. In horses with inflammatory diseases, the rate of glucose infusion and the amount of vitamins administered were higher than in horses with nonstrangulated obstruction. The proportion of horses that received lipid emulsion was higher among those with nonstrangulated and strangulated obstruction than in the group with inflammatory conditions. Because of the diverse group of diseases and the variability in the clinical signs, evaluating the effect of PN on disease outcome was not possible. A prospective study to compare horses with similar clinical conditions treated and not treated with PN is needed to evaluate fully the benefits of PN, and to establish guidelines for patients election for PN.
Density and binding characteristics of beta‐adrenoceptors in the normal and failing equine myocardium
Authors: HORN J. , BAILEY S. , BERHANE Y. , MARR C. M. , ELLIOTT J.
Published: April 2007

Beta‐adrenoceptors are important regulators of cardiac function and their characteristics are known to chagne in human and canine diseased myocardium. This study aimed to determine the density and subtypes of beta‐adrenoceptors in the normal and failing equine ventricular myocardium. Membrane preparations of the left papillary muscles were incubated with increasing concentrations of the nonselective beta‐adrenoceptor antagonist [3H]‐CGP12177. Saturable and reversible binding of [3H]‐CGP12177 to myocardial membranes was demonstrated with Kd values (± s.d.) of 0.49 ± 0.40 and 0.43 ± 0.22 nmol/l and Bmax values of 93.4 ± 20.5 and 110.0 ± 21.2 and fmol/mg protein for normal (n = 19) and heart failure (n = 10) tissues, respectively. Heart failure had no significant effect on the density of ventricular beta‐adrenoceptors.

The cardiac beta‐adrenoceptors were further characterised by studying displacement of [3H]‐CGP12177 (0.6 nmol/l) with the beta1‐selective antagonists CGP20712A and the beta2‐selective antagonist ICI118.551. In normal ventricular muscle, CGP20712A was 26 times more potent than ICI118.551 (Ki values 30.4 ± 24.8 and 814.1 ± 485.2 nmol/l, respectively). In heart failure cases, CGP 20712A curves were monophasic with a Ki value of 45.6 ± 39.7 nmol/l. ICI 118.551 curves were biphasic in 5 horses where 11–31% of the cardiac beta‐adrenoceptors had a high affinity for ICI 118.551.

These data suggest that the normal equine ventricular myocardium possesses predominately beta1‐adrenoceptors, with no evidence for co‐existence of a significant population of beta2‐adrenoceptors. The density of beta‐adrenoceptors did not appear to change in heart failure, but the appearance of receptors with a high affinity for ICI118.551 may suggest that, in some cases, heart failure increases the expression of beta2‐adrenoceptors in equine ventricular myocardium.

This study provides an insight into the role of the adrenergic system in heart disease in the horse. Further studies in this area are warranted.
Intradermal skin testing in Icelandic horses in Austria
Authors: KOLM‐STARK G. , WAGNER R.
Published: April 2007

Icelandic horses in Austria are commonly affected by an allergic inflammatory skin disease recurring during the summer seasons, which shares characteristic features withCulicoideshypersensitivity. However, the causative agents have not yet been identified. Therefore, intradermal skin testing (IDST) with a standardised extract ofCulicoides variipennisand 21 other allergens relevant within Austria was performed in 81 Icelandic horses. All horses included into the study were treated regularly with ivermectin and had no history of administration of anti‐inflammatory drugs. Forty‐three of these horses were affected by summer seasonal recurrent dermatitis (SSRD). No history or signs of any other disease were evident in any horse. Pruritic dermatitis due to ectoparasites, bacteria and dermatophytes were ruled out by means of fungal culture, skin scraping and biopsy.

Culicoides variipennisantigens evoked a positive cutaneous reaction in 1 of 38 normal and 3 of 43 SSRD horses at the proposed dilution of 1:50,000 or 1:25,000, and in 24 of 38 normal and 13 of 43 SSRD horses at a dilution of 1:10,000. Furthermore, no significant differences in onset or intensity of skin reactions to the 21 other allergens, including pollens, moulds, mites and insects, except deerfly and horsefly, were obvious between the 2 groups. Efficiency (percentage of correct results) for the used antigens in the skin test was 0.47–0.60. Maximal sensitivity was 0.51. Altogether, 38 of 43 SSRD horses and 28 of 38 normal horses were positive 4 h after allergen administration. The divergence between IDST results and manifestation of clinical signs found in this study underlines the difficulties associated with establishing a skin test protocol in horses within a geographic area. Whether the outcome of this study would have been influenced significantly by usingCulicoidesspp. present in Austria has to be clarified in future research.
Effect of nutritional antioxidant supplementation on systemic and pulmonary antioxidant status, airway inflammation and lung function in heaves‐affected horses
Authors: KIRSCHVINK N. , FIÉVEZ L. , BOUGNET V. , ART T. , DEGAND G. , SMITH N. , MARLIN D. , ROBERTS C. , HARRIS P. , LEKEUX P.
Published: April 2007

An oxidant/antioxidant imbalance in favour of oxidants has been identified as playing a decisive role in the pathogenesis of chronic inflammatory airway diseases. Nutritional antioxidant supplementation might reduce oxidative damage by enhancement of the antioxidant defence, thereby modulating inflammatory processes. In a placebo‐controlled, blind study, it was tested whether a dietary antioxidant supplement administered for 4 weeks would improve lung function and reduce airway inflammation in heaves‐affected horses. Eight horses in clinical remission of heaves were investigated at rest and after a standardised exercise test before and after treatment with an antioxidant supplement (consisting of a mixture of natural antioxidants including vitamins E and C and selenium from a variety of sources) or placebo (oatfeed pellets without additive). Pulmonary function and exercise tolerance were monitored; systemic and pulmonary lining fluid uric acid, glutathione and 8‐epi‐PGF2αwere analysed, and bronchoalveolar lavage (BAL) cytology and inflammatory scoring of the airways were performed. The antioxidant treatment significantly improved exercise tolerance and significantly reduced endoscopic inflammatory score. Plasma uric acid concentrations were significantly reduced, suggesting down regulation of the xanthine‐dehydrogenase and xanthine‐oxydase pathway. Haemolysate glutathione showed a nonsignificant trend to increase, while plasma 8‐epi‐PGF2αremained unchanged. Pulmonary markers and BAL cytology were not significantly affected by antioxidant supplementation. The present study suggests that the antioxidant supplement tested modulated oxidant/antioxidant balance and airway inflammation of heaves‐affected horses.
The effect of co‐culture on the development ofin vitromatured equine oocytes after intracytoplastic sperm injection
Authors: ROSATI I. , BERLINGUER F. , BOGLIOLO L. , LEONI G. , LEDDA S. , NAITANA S.
Published: April 2007

It is clear that, in the horse, there are many weak links in the process ofin vitroembryo production; an optimal culture system for equine oocytes does not exist, and related data are conflicting. Therefore, the ability of 3 different culture systems to support embryonic development of ICSI horse oocytes was examined. Oocytes (n = 261) suitable for culture were collected from 55 ovaries and divided, according to cumulus morphology, into 2 categories: expanded cumulus and compacted cumulus. Oocytes with expanded and compacted cumulus were cultured forin vitromaturation in TCM 199 + 10% FCS + 0.1 iu/ml FSH/LH at 38.5°C under 5% CO2in air for 24 and 40 h, respectively. Oocytes (n = 149) reached metaphase II and were subjected to ICSI with frozen semen and then incubated in 3 different culture systems: A) TCM 199 + 10% FCS alone or B) on granulosa cell monolayer, C) SOF + MEM aminoacids + 0.8% BSA. Cultural conditions were 39°C and 5% CO2in air for A and B, while a gas mixture (5% CO2, 5% O2, 90% N2) was used for C. The fertilisation rate was 32%. The cleavage rate inGroup Awas 74.4% (32/43); 18 embryos reached 2–6 cell stage, eight 8–16 cell, four 16–32 cell and two >32 cell. InGroup B, the cleavage rate was 73.5% (36/49) with better results in embryonic development; 14 reached 2–6 cell stage, eighteen 8–16 cell, twelve 16–32 cell and five >32 cell. InGroup C, the cleavage rate was significantly lower then inAandB; only 15 of 47 ICSI oocytes (39.1%) cleaved with maximum development to 2–6 cell stage. The remaining oocytes (68.1%) degenerated during culture. In conclusion, IVM horse oocytes can be fertilisedin vitrowith high efficiency with ICSI and co‐culture systems showed to be superior in supportingin vitroembryo culture compared to simple ones. The identification of the factors beneficial toin vitroembryo development provided by the somatic cells could be important to optimise the embryo culture systems for equine embryos.
Expression of a 4‐(hydroxy‐3‐nitro‐phenyl) acetyl (NP) specific equi‐murine IgE antibody that mediates histamine release in vitro and a type I skin reaction in vivo
Authors: WAGNER B. , SIEBENKOTTEN G. , LEIBOLD W. , RADBRUCH A.
Published: April 2007

Due to characteristic clinical signs, immunoglobulins of isotype E (IgE) are believed to be involved in several allergic diseases of the horse. To date, closer investigations have been hampered by the fact that neither purified equine IgE nor anti‐equine IgE monoclonal antibodies were available for IgE isotype determination. As an approach to solve this problem, we constructed a stable cell line (EqE6) that expresses recombinant equi‐murine IgE specific for 4‐(hydroxy‐3‐nitro‐phenyl) acetyl (NP). Biochemical analysis of the purified protein revealed a highly glycosilated IgE monomer of approximately 230,000 Da. The biological ability of the NP‐IgE to mediate histamine release after crosslinking with antigen was demonstrated in vitro using equine blood leucocytes. In vivo, the intradermal application of NP‐IgE followed by antigen crosslinking induced a type I hypersensitivity skin reaction in horses. Both results indicate that the recombinant NP‐IgE contains an intact and functional FceRI binding site and mediates effector functions in equine basophils and cutaneous mast cells. This equi‐murine IgE can be used for the production of IgE‐specific polyclonal and monoclonal antibodies. In addition, the NP specificity allows the antigen‐specific activation of equine Fce‐receptor‐expressing cells, such as mast cells and basophils. This property could be used to investigate IgE‐mediated mechanisms for a better understanding of equine type I allergic diseases.
Serum amyloid A (SAA) as an aid in the management of infectious disease in the foal: comparison with total leucocyte count, neutrophil count and fibrinogen
Authors: HULTÉN C. , DEMMERS S.
Published: April 2007

Differentiation between infectious and noninfectious disease and rapid initiation of accurate treatment are essential in managing diseases in the neonatal and young foal. Identification of useful inflammatory markers for these purposes is, therefore, of great importance. The aim of this study was to compare the responses of the acute phase protein serum amyloid A (SAA) with the responses of fibrinogen and total leucocyte and neutrophil counts in infectious diseases encountered in the young foal, and to assess whether SAA measurements give additional information useful in the management of these diseases. In a prospective study, foals (n = 25) showing clinical signs indicative of infectious disease were blood sampled on admission and then daily or every second day during hospitalisation. The main presenting signs were neonatal weakness (n = 9), pneumonia (n = 6) and diarrhoea (n = 10). SAA and fibrinogen concentrations on admission were higher in foals with bacterial infections (n = 8) than in foals with nonbacterial or uncertain diagnoses (n = 17). On admission, weak foals with negative blood cultures (n = 3) had normal SAA and fibrinogen concentrations and varying total leucocyte and neutrophil counts. Foals with positive blood cultures (n = 2) had markedly increased SAA, decreased or increased fibrinogen concentration and leuco‐ and neutropenia. Those with ambiguous blood cultures (n = 3) had moderate to markedly increased SAA concentrations and normal fibrinogen concentration, leucocyte and neutrophil counts on admission. All foals with negative or ambiguous blood cultures recovered and had normal or decreasing SAA concentration on discharge. Both foals with a positive blood culture were subjected to euthanasia. One foal born with equine herpesvirus‐1 infection had moderately increased SAA and normal fibrinogen concentration and leuco‐ and neutropenia. Foals withRhodococcus equipneumonia had increased concentrations of all parameters on admission. On discharge, recovered foals had normal SAA concentrations, whereas fibrinogen and total white blood cell count and neutrophil counts were still increased. There were no consistent inflammatory changes in the parameters measured in diarrhoeic foals and there was no statistical difference between rotavirus‐positive (n = 4) and ‐negative (n = 6) foals in this respect.

The results of this investigation suggest that SAA might be an aid in the differential diagnostic procedure of neonatally weak foals and in foals with diarrhoea as the main presenting clinical sign and that SAA measurements could add information in the monitoring of treatment inRhodococcus equipneumonia by responding more rapidly than the markers used to date.
In vitroevaluation of nonrigid support systems for the equine metacarpophalangeal joint
Authors: SMITH R. K. W. , McGUIGAN M. P. , HYDE J. T. , DALY A. S. G. , PARDOE C. H. , LOCK A. N. , WILSON A. M.
Published: April 2007

Metacarpophalangeal (MCP) joint extension is primarily resisted by the digital flexortendons and suspensory ligament. A variety of external support techniques are used to protect these supporting structures from or after injury by resisting MCP joint extension, although not all are effective and/or practical for use in an exercising horse. In this study, 7 forelimbs were loadedin vitroto determine the effect of a simple gamgee bandage, a 3‐layered bandage with and without a contoured palmar splint, a neoprene exercise boot, and an innovative carbon fibre composite exercise boot (Dalmar tendon support boot). There was no significant resistance to MCP joint extension by the gamgee or neoprene exercise boot. The 3‐layered bandage had a significant (P < 0.01) supporting effect at MCP angles of ≥245°, and when combined with the contoured splint at angles of ≥230°. The Dalmartendon support boot resisted MCP extension at angles of ≥245° (settings 1 and 2) and ≥225° (setting 3). These data demonstrate that the contoured splint and the Dalmar tendon support boot (which is also easily fitted for use during exercise) are useful for the management of tendon/ligament injury and during rehabilitation.
Foraging enrichment for stabled horses: effects on behaviour and selection
Authors: GOODWIN D. , DAVIDSON H. P. B. , HARRIS P.
Published: April 2007

The restricted access to pasture experienced by many competition horses has been linked to the exhibition of stereotypic and redirected behaviour patterns. It has been suggested that racehorses provided with more than one source of forage are less likely to perform these patterns; however, the reasons for this are currently unclear. To investigate this in 4 replicated trials, up to 12 horses were introduced into each of 2 identical stables containing a single forage, or 6 forages for 5 min. To detect novelty effects, in the first and third trials the single forage was hay. In the second and fourth, it was the preferred forage from the preceding trial. Trials were videotaped and 12 mutually exclusive behaviour patterns compared. When hay was presented as the single forage (Trials 1 and 3), all recorded behaviour patterns were significantly different between stables; e.g. during Trial 3 in the ‘Single’ stable, horses looked over the stable door more frequently (P < 0.001), moved for longer (P < 0.001), foraged on straw bedding longer (P < 0.001), and exhibited behaviour indicative of motivation to search for alternative resources (P < 0.001) more frequently. When a previously preferred forage was presented as the single forage (Trials 2 and 4) behaviour was also significantly different between stables, e.g. in Trial 4 horses looked out over the stable door more frequently (P < 0.005) and foraged for longer in their straw bedding (P < 0.005).

Further study is required to determine whether these effects persist over longer periods. However, these trials indicate that enrichment of the stable environment through provision of multiple forages may have welfare benefits for horses, in reducing straw consumption and facilitating the expression of highly motivated foraging behaviour.
Intradermal skin tests in equine dermatology: a study of 83 horses
Authors: LEBIS C. , BOURDEAU P. , MARZIN‐KELLER F.
Published: April 2007

Allergic diseases are often diagnosed clinically in the horse without performing diagnostic tests. The purpose of this work was to contribute to the validation of intradermal skin tests in the horse. Eighty‐three horses, 14 showing skin or respiratory signs of supposed allergic origin, were subjected to an intradermal skin test using 6 different allergens, positive and negative controls. The tests were read for all animals after 20 min, and for 29 horses after 1 and 4 h. Additionally, 19 horses were tested a few months apart. The comparison after 20 min of the cutaneous reactions to allergens and to positive and negative controls allowed us to propose a threshold of positivity; skin reactions with a diameter above or equal to 15 mm, or with at least a 13 mm diameter and a skin thickness similar to the positive control. There was a marked difference between the healthy group and the allergic group forCulex pipiensandDermatophagoides farinae, although positive reactions were not rare in the healthy group.Tabanussp. gave positive reactions in both healthy and allergic animals. There was no significant variation in the reactions observed after 20 min and after 60 min. After 4 h, the progression of the reactions was highly variable and negative controls showed a certain number of positive reactions, which negated their reliability at the point in time, and made it difficult to interpret the other allergens. Finally, the repeatability of intradermal skin tests reactions after 20 min was poor, and probably related to the influence of seasonality for some of the allergens. Further studies are required, notably with others allergens, to interpret intradermal skin tests' responses in clinical practice.
Effectiveness of a two‐dose regimen of prostaglandin administration in inducing luteolysis without adverse side effects in mares
Authors: IRVINE C. H. G. , McKEOUGH V. ‐L. , TURNER J. E. , ALEXANDER S. L. , TAYLOR T. B.
Published: April 2007

Our objectives were to determine whether repeated administration of prostaglandin F2α (PGF2α) to simulate the endogenous mode of secretion would be more effective than a single injection in inducing luteolysis and enable use of smaller doses less likely to cause adverse side effects. The main study comprised 43 dioestrous mares, who were given i.m. either a single 10 mg dose of natural PGF2α (n = 22) or 2 doses of 0.5 mg PGF2α 24 h apart (n = 21). The intensity of side effects was assessed in 8 dioestrous mares given 5, 1.5, 0.5 or 0 mg PGF2α in consecutive cycles.

Two doses of 0.5 mg PGF2α 24 h apart caused lysis of the corpus luteum in all mares, whether this was determined from a fall in plasma progesterone concentrations or reproductive tract/behavioural changes; and when 10 mg PGF2α was given, the corpus luteum was lysed in 17 of 22 mares i.e. a lower proportion (P= 0.0485). A single dose of 0.5 mg PGF2α was no more effective than saline in inducing luteolysis. The intensity of side effects of PGF2α increased with dose. Although the 0.5 mg dose was no more likely than saline to cause sweating ormuscle spasms, it raised plasma cortisol concentrations and prevented the decline in heart rate seen after saline. We conclude that a 2 dose regimen of administration increases the luteolytic efficacy of PGF2α and thereby provides a way to minimise adverse side effects.