[Prevalence of health problems in midlife Swiss warm-blooded horses]. / Auftreten gesundheitlicher Probleme beim Schweizer Warmblutpferd ­mittleren Alters.

INTRODUCTION: The breeding of a healthy horse is the basic requirement for optimal performance. This is also specifically stated in the breeding goal of the Swiss warmblood horse and should be achieved through a strict selection of the stallions. The aim of this retrospective study was to assess the current state of the population to optimize breeding. Data on the health status of Swiss warmblood horses in the age between 6 and 16 years (midlife) were collected by a telephone survey and analyzed descriptively. Following the heritability of the most common health problems were estimated. Data on 1,861 horses were collected between 2016 and 2018. Lameness (34%), colic (22%), sarcoids (19%), and pastern dermatitis (16%) were among the most common health problems, followed by back problems (13%), cough (10%), urticaria (10%), free fecal water syndrome (9%), nasal discharge (8%) and sweet itch (4%). Lameness was observed in 49% of the cases in the forelimbs, in 25% in the hindlimbs and in 26% in both. 27% of horses with colic have been hospitalized once and 8% have undergone colic surgery. Sarcoids became fewer or smaller in 89% of the treated and in 58% of the untreated horses. A significant relationship between treatment and the status of the sarcoids was demonstrated (p .

INTRODUCTION: L'élevage d'un cheval en bonne santé représente une condition de base pour une performance optimale. Ceci est également spécifiquement mentionné dans l'objectif d'élevage du cheval de sang suisse et doit être atteint par une sélection stricte des étalons. Afin d'optimiser l'élevage, il faut connaître l'état actuel de la population, ce qui était le but de cette étude rétrospective. Au moyen d'une enquête téléphonique, des données sur l'état de santé des chevaux de sang suisses âgés de 6 à 16 ans (âge moyen) ont été collectées et traitées de manière descriptive. Les héritabilités des problèmes de santé les plus courants ont ensuite été estimées. Au total, les données de1861 chevaux ont été collectés entre 2016 et 2018. Les boiteries (34%), les coliques (22%), les sarcoïdes (19%) et les crevasses (16%) figuraient parmi les problèmes de santé les plus courants, suivis des problèmes de dos (13%), de la toux (10%), des urticaires (10%), d'écoulements anaux (« Kotwasser ¼) (9%), d'écoulements nasaux (8%) et de dermite estivale (4%). Chez 49% des chevaux boiteux, il s'agissait d'une boiterie antérieure, chez 25% d'une boiterie postérieure et chez 26% d'une boiterie impliquant antérieurs et postérieurs. 27% des chevaux présentant des coliques avaient été hospitalisés et 8% avaient subi une chirurgie de coliques. Les sarcoïdes sont devenus moins nombreux ou plus petits chez 89% des chevaux traités mais également chez 58% des chevaux non traités. Une relation significative entre le traitement et l'état des sarcoïdes a pu être démontrée (p .

Serum acylcarnitine profile in endurance horses with and without metabolic dysfunction.

Mitochondrial ß-oxidation is essential in fat metabolism and can be monitored with blood acylcarnitine profiling, as partly degraded fatty acids accumulate as their carnitine esters. To guarantee continuous energy supply during long-distance exercise, endurance horses oxidise considerable amounts of fat in the mitochondrion. In endurance races over 80 km, glycogen depletion is evident in equine slow-twitch high oxidative muscle fibres and as a consequence, horses participating in endurance races over 80 km rely almost entirely on ß-oxidation of fatty acids. This study investigated mitochondrial fatty acid ß-oxidation in endurance horses exposed to long-distance exercise. Electrospray tandem mass spectrometry analysis of serum acylcarnitine profiles from 10 Arab horses was performed before and after a 160 km endurance race. Results were analysed statistically using ANOVA. Mean speed over the entire race in finishing horses was 16.7 ± 1.2 km/h. Endurance exercise increased mitochondrial ß-oxidation approximately eight-fold (pre-race, 5648.62 ± 1508.52 nmol/L; post-race, 44,243.17 ± 11,504.45 nmol/L; P = 0.001). In these horses, there was an approximately 17-fold increased lipolysis, as demonstrated by elevated serum concentrations of non-esterified fatty acids (NEFA; pre-race, 0.08 ± 0.08 mmol/L; post-race, 1.32 ± 0.36 mmol/L; P < 0.001). In comparison, four Arab horses with poor performance showed an approximately five-fold increase in mitochondrial ß-oxidation (pre-race, 5286.17 ± 3355.16 nmol/L; post-race, 26,660.57 ± 10,064.27 nmol/L; P = 0.009); there was a 29-fold increase in NEFA (pre-race, 0.02 ± 0.01 mmol/L; post-race, 0.58 ± 0.07 mmol/L; P = 0.006) in these horses. Similar post-exercise free carnitine:acetylcarnitine ratios in both groups suggest that the availability of carnitine in long-distance endurance horses might limit performance.

Cardiovascular variables in eventing and endurance horses over a season.

INTRODUCTION: The objectives of this study were to describe the changes in clinical cardiovascular examination variables over a competition season in groups of competitive eventing and endurance horses and to compare these findings to non-competitive controls of the same breeds. ANIMALS: This study included two eventing horses, 11 endurance horses, and 13 eventing and seven endurance control breed-matched horses. MATERIALS AND METHODS: Cardiovascular examinations were performed before starting the competition season, in the middle and at the peak/end of the competition season. Examinations included auscultation of the heart; M-mode echocardiographic measurements and calculated values; left atrial, pulmonary artery, and aortic diameters; color flow Doppler; exercise electrocardiograms (ECG) measuring peak heart rates and quantifying premature complexes; and 24-h continuous ECGs quantifying premature complexes per hour. RESULTS: Auscultation, echocardiograms, arrhythmias during exercise, and 24-h continuous ECGs did not change significantly throughout the season (p > 0.05 for all variables). CONCLUSION: Cardiovascular examination variables of eventing and endurance horses throughout a competition season are reported here for the first time. Although the present study did not reveal significant changes, data should be interpreted carefully as only a small number of horses were examined.

Increased adrenocortical response to adrenocorticotropic hormone (ACTH) in sport horses with equine glandular gastric disease (EGGD).

This study tested the hypothesis that adrenocortical function would be altered in horses with equine gastric ulcer syndrome (EGUS). Twenty-six sport horses competing at national or international levels in eventing (n=15) or endurance (n=11) were subjected to a gastroscopic examination and an adrenocorticotropic hormone (ACTH) stimulation test. Salivary cortisol concentrations were measured before (baseline) and after (30, 60, 90, 120 and 150min) IV ACTH injection (1µg/kg bodyweight). Within EGUS, two distinct diseases, equine squamous gastric disease (ESGD) and equine glandular gastric disease (EGGD), can be distinguished. ESGD was diagnosed in 8/11 (73%; 95% confidence intervals [95%CI], 43-92%) endurance horses and 5/15 (33%; 95% CI, 14-58%) eventing horses. EGGD was observed in 9/11 (82%; 95% CI, 53-96%) endurance horses and 9/15 (60%; 95% CI, 35-81%) eventing horses. The presence or severity of ESGD was unrelated to the presence or severity of EGGD. ACTH stimulation induced a larger increase in cortisol concentration in horses with moderate EGGD than in horses with mild EGGD. Cortisol concentration during the entire sampling period (total increase in cortisol concentration during the entire sampling period [dAUC], 31.1±6.4ng/mL) and the highest measured concentration at a single time point (maximal increase in cortisol concentration [dMAX], 10.3±2.3ng/mL) were increased (P=0.005 and P=0.038, respectively), indicating that horses with glandular gastric disease exhibited increased adrenocortical responses to ACTH stimulation. These results suggest that EGGD might be associated with an enhanced adrenocortical sensitivity. Further investigations are warranted to confirm the association between adrenocortical sensitivity and EGGD and to elucidate the pathophysiological mechanisms involved.

Heritabilities of health traits in Swiss Warmblood horses.

REASONS FOR PERFORMING STUDY: There is a lack of evidence regarding genetic parameters of health traits in Swiss Warmblood horses. OBJECTIVES: To estimate heritabilities of equine sarcoid disease, horn quality of hooves, prognathism and increased filling of talocrural joints as a possible indicator for osteochondrosis in Swiss Warmblood horses examined at the field tests for 3-year-olds between 2005 and 2013. STUDY DESIGN: Retrospective analysis of breed society database. METHODS: Swiss Warmblood horses were examined clinically by 13 veterinarians at field tests in Switzerland between 2005 and 2013. The presence of sarcoids, horn quality of the hooves, incisor occlusion and increased joint filling were assessed and recorded. Records of 3715 horses were integrated in a pedigree comprising 217,282 horses. Variance components and heritabilities were estimated on the liability scale using multiple-trait Gibbs sampler for animal models (MTGSAM). RESULTS: The prevalences of the examined traits were rather low ranging from 2.4 to 13.0%. Heritabilities estimated were 0.21 ± 0.07 for the occurrence of sarcoids, 0.04 ± 0.02 for hooves with markedly brittle and friable horn quality, 0.03 ± 0.01 for hooves with marked growth ring formation, 0.06 ± 0.03 for prognathism and 0.08 ± 0.04 for increased filling of the talocrural joint (an indicator of possible osteochondrosis). The influence of the examiner on the variance of these observations was considerable. CONCLUSIONS: With the exception of equine sarcoid disease, estimates for the heritabilities for the traits examined here were low. A standardised examination protocol may reduce the variance due to the examiner.

Repeatability of the ACTH stimulation test as reflected by salivary cortisol response in healthy horses.

The aim of this study was to further characterize the ACTH stimulation test as reflected by salivary cortisol response and to measure the short- and long-term repeatability of it in healthy horses as a tool to assess the capacity of the adrenal cortex to secrete cortisol. Nineteen healthy horses were subjected to 3 ACTH stimulation tests. Intervals were 2 wk and 5 mo between the first and second and the second and third tests, respectively. A dose of 1-µg/kg BW synthetic ACTH was injected intravenously. Saliva samples were collected at baseline and at 30, 60, 90, 120, 150, and 180 min after administration for cortisol measurements using a competitive enzyme immunoassay. A repeated measures ANOVA was used to compare values within and among horses. Mean ± SD total increase in cortisol concentrations integrated over the entire sampling period was 34.5 ± 11.0 ng/mL. The highest measured concentration at a single time point was 9.7 ± 2.7 ng/mL and was reached after 122 ± 22 min. For the short- and long-term repeatability, intraclass correlation coefficient was 0.90 and 0.33, respectively. The 3 ACTH stimulation tests results differed significantly among (P < 0.00001) but not within (P = 0.538) individual horses. The Freiberger stallions had a higher salivary cortisol baseline concentration and a lower response to ACTH stimulation as compared with Warmblood mares and geldings. The present study confirmed that the administration of ACTH in healthy horses reliably stimulates the salivary secretion of cortisol and shows that the test is repeatable in the short- and long-term.

Retrospective evaluation of all recorded horse race starts in Switzerland during a four year period focusing on discipline-specific risk factors for clinical events.

REASONS FOR PERFORMING STUDY: Racetrack injuries are of welfare concern and the prevention of injuries is an important goal in many racing jurisdictions. Over the years this has led to more detailed recording of clinical events on racecourses. However, risk factor analyses of clinical events at race meetings have not been previously reported for Switzerland. OBJECTIVES: To identify discipline-specific factors that influence the occurrence of clinical events during race meetings with the ultimate aim of improving the monitoring and safety of racetracks in Switzerland and optimising racehorse welfare. STUDY DESIGN: Retrospective study of horse race data collected by the Swiss horse racing association. METHODS: All race starts (n = 17,670, including 6198 flat, 1257 obstacle and 10,215 trot race starts) recorded over a period of 4 years (2009-2012) were analysed in multivariable mixed effect logistic regression models including horse and racecourse related data. The models were designed to identify discipline-specific factors influencing the occurrence of clinical events on racecourses in Switzerland. RESULTS: Factors influencing the risk of clinical events during races were different for each discipline. The risk of a clinical event in trot racing was lower for racing on a Porphyre sand track than on grass tracks. Horses whose driver was also their trainer had an approximately 2-fold higher risk for clinical events. In obstacle races, longer distances (2401-3300 m and 3301-5400 m, respectively) had a protective effect compared with racing over shorter distances. In flat racing, 5 racecourses reported significantly fewer clinical events. In all 3 disciplines, finishing 8th place or later was associated with clinical events. CONCLUSIONS: Changes in management that aim to improve the safety and welfare of racehorses, such as racetrack adaptations, need to be individualised for each discipline.

The physiological consequences of crib-biting in horses in response to an ACTH challenge test.

Stereotypies are repetitive and relatively invariant patterns of behavior, which are observed in a wide range of species in captivity. Stereotypic behavior occurs when environmental demands produce a physiological response that, if sustained for an extended period, exceeds the natural physiological regulatory capacity of the organism, particularly in situations that include unpredictability and uncontrollability. One hypothesis is that stereotypic behavior functions to cope with stressful environments, but the existing evidence is contradictory. To address the coping hypothesis of stereotypies, we triggered physiological reactions in 22 horses affected by stereotypic behavior (crib-biters) and 21 non-crib-biters (controls), using an ACTH challenge test. Following administration of an ACTH injection, we measured saliva cortisol every 30 min and heart rate (HR) continuously for a period of 3h. We did not find any differences in HR or HR variability between the two groups, but crib-biters (Group CB) had significantly higher cortisol responses than controls (Group C; mean ± SD: CB, 5.84 ± 2.62 ng/ml, C, 4.76 ± 3.04 ng/ml). Moreover, crib-biters that did not perform the stereotypic behavior during the 3-hour test period (Group B) had significantly higher cortisol levels than controls, which was not the case of crib-biters showing stereotypic behavior (Group A) (B, 6.44 ± 2.38 ng/ml A, 5.58 ± 2.69 ng/ml). Our results suggest that crib-biting is a coping strategy that helps stereotypic individuals to reduce cortisol levels caused by stressful situations. We conclude that preventing stereotypic horses from crib-biting could be an inappropriate strategy to control this abnormal behavior, as it prevents individuals from coping with situations that they perceive as stressful.

Replication and fine-mapping of a QTL for recurrent airway obstruction in European Warmblood horses.

Recurrent airway obstruction (RAO), or 'heaves', is a common performance-limiting allergic respiratory disease of mature horses. It is related to sensitization and exposure to mouldy hay and has a familial basis with a complex mode of inheritance. In a previous study, we detected a QTL for RAO on ECA 13 in a half-sib family of European Warmblood horses. In this study, we genotyped additional markers in the family and narrowed the QTL down to about 1.5 Mb (23.7-25.2 Mb). We detected the strongest association with SNP BIEC2-224511 (24,309,405 bp). We also obtained SNP genotypes in an independent cohort of 646 unrelated Warmblood horses. There was no genome-wide significant association with RAO in these unrelated horses. However, we performed a genotypic association study of the SNPs on ECA 13 in these unrelated horses, and the SNP BIEC2-224511 also showed the strongest association with RAO in the unrelated horses (p(raw) = 0.00037). The T allele at this SNP was associated with RAO both in the family and the unrelated horses. Thus, the association study in the unrelated animals provides independent support for the previously detected QTL. The association study allows further narrowing of the QTL interval to about 0.5 Mb (24.0-24.5 Mb). We sequenced the coding regions of the genes in the critical region but did not find any associated coding variants. Therefore, the causative variant underlying this QTL is likely to be a regulatory mutation.

Evaluation of a mask for breath-by-breath respirometry during exercise in horses.

REASONS FOR PERFORMING STUDY: The ability to obtain breath-by-breath measures of ventilatory mechanics for the entirety of an exercise test, regardless of speed(s) or duration enables evaluations of equine ventilation during exercise that are necessary for assessments of performance. OBJECTIVE: Evaluation of a new ergospirometer (Quadflow; QF) system's accuracy and repeatability for measuring pulmonary variables in contrast to the established pneumotachometer-based system (control) and assessment of its effects, if any, on exercise capacity at high speeds. MATERIALS AND METHODS: Five Thoroughbred horses each performed 10 incremental exercise tests to fatigue, 5 with the QF system and 5 with an open-circuit flow system. Measures of pulmonary variables were evaluated to determine repeatability. Heart rate, pulmonary variables, arterial blood gases, distance run and time to fatigue measured with each system were compared to assess similarity of results and effect on performance. RESULTS: Results from both systems had high repeatability with low coefficients of variation. The QF was associated with greater resistance to airflow, higher breathing rate at submaximal speeds, lower minute ventilation and peak inspiratory and expiratory airflows, greater acidaemia, hypoxaemia and hypercapnoea, and decreased total run time and total distance run when compared to control system results. CONCLUSION: The greater resistance of the QF was responsible for altered blood gases, respiratory parameters and performance when compared to the control mask. The QF system reliably measured equine pulmonary airflows and volumes and is suitable for research and clinical use provided optimal gas exchange and best possible physical performance are not required.

Association of increased tracheal mucus accumulation with poor willingness to perform in show-jumpers and dressage horses.

The objective of this study was to examine the association of pharyngeal lymphoid hyperplasia (PLH), recurrent laryngeal neuropathy (RLN), mucus accumulation (MA) score and tracheobronchial secretion neutrophil percentage (TBS-N) with rider-assessed performance in sport horses. Airway endoscopy scores, tracheobronchial secretion cytology, rider-assessed general impression and willingness to perform were investigated in 171 top-level sport horses. Increased MA appears to be associated with poor willingness to perform in sport horses. Older horses had decreased PLH scores and increased TBS-N. Mucus accumulation scores > or =3 were associated with increased odds (mean 9.92; upper and lower 95% confidence intervals: 1.5-64.6) of poor rather than excellent willingness to perform. A TBS-N of 20-50% compared with <20% was associated with decreased odds (median 0.11; upper and lower 95% CI: 0.02-0.66) of poor rather than excellent willingness to perform. In addition, horses with an RLN grade > or =2 had significantly higher odds for giving a poorer general impression and willingness to perform. This finding, however, must be interpreted with caution, since only two horses had significant RLN (grade > or =3).

Individual and social determinants of spontaneous group movements in cattle and sheep.

Group-living animals travel together to collectively exploit the resources of their environment. This study investigates how social relationships and individual temperament traits affect movement orders in domestic cattle and sheep. We analysed spontaneous group movements occurring at pasture after a resting period in a group of 15 18-month-old Charolais heifers and a group of 19 1-year-old Romane ewe-lambs. For each species, animals had similar social experience and no kinship ties. Before that, animals were observed within the group to establish their social status (e.g. dominance and preferential relationships, and sociability), then in individual tests in order to assess their emotional traits. In both species, most individuals could initiate a group movement but some individuals were more successful than others in recruiting the rest of the group. Ewe-lambs, and to a lesser extent heifers, held preferential positions during travel. We did not find any significant correlations in either species between animal order and their position in the dominance hierarchy (heifers: P = 0.438; ewe-lambs: P = 0.574) while individuals linked by preferential bonds frequently followed each other during group movements (heifers: P < 0.001; ewe-lambs: P < 0.001). With regard to social traits, heifers with a low cohesion index, and with a lower number of partners with whom they develop frequent affinitive interactions, acted more frequently as 'first movers' (P = 0.040 and 0.023, respectively), as well as did ewe-lambs with a high spatial independency index (P = 0.002). Ewe-lambs with the highest cohesion indices were more frequently observed in front of the group while moving halfway between departure and arrival (P = 0.028). We did not find significant correlations between individual positions during group movements and emotional traits such as reactivity, boldness and fearfulness. We conclude that preferential bonds and individual traits related to social dependence were more influential in spontaneous group movements at pasture than were emotional traits and dominance status.

[Genetics of recurrent airway obstruction (RAO)]. / Genetik der rezidivierenden Atemwegsobstruktion (RAO).

Recurrent airway obstruction (RAO) is a multifactorial and polygenic disease. Affected horses are typically 7 years of age or older and show exercise intolerance, increased breathing effort, coughing, airway neutrophilia, mucus accumulation and hyperreactivity as well as cholinergic bronchospasm. The environmental factors responsible are predominantly allergens and irritants in haydust, but the immunological mechanisms underlying RAO are still unclear. Several studies have demonstrated a familiar predisposition for RAO and it is now proven that the disease has a genetic basis. In offspring, the risk of developing RAO is 3-fold increased when one parent is affected and increases to almost 5-fold when both parents have RAO. Segregation analysis in two high-prevalence families demonstrated a high heritability and a complex inheritance with several major genes. A whole genomescan showed chromosome-wide significant linkage of seven chromosomal regions with RAO. Of the microsatellites, which were located near atopy candidate genes, those in a region of chromosome 13 harboring the IL4R gene were strongly associated with the RAO phenotype in the offspring of one RAO-affected stallion. Furthermore, IgE-levels are influenced by hereditary factors in the horse, and we have evidence that RAO-affected offspring of the same stallion have increased levels of specific IgE against moldspore allergens. The identification of genetic markers and ultimately of the responsible genes will not only allow for an improved prophylaxis, i.e. early identification of susceptible individuals and avoidance of high-risk matings, but also improve our ability to find new therapeutic targets and to optimize existing treatments.

[Hereditary diseases in the horse: I. Monogenetic diseases]. / Erbkrankheiten beim Pferd: I. Monogen vererbte Erkrankungen.

Overall, monogenetic hereditary diseases are less important for the breeding industry than polygenetic diseases because they are relatively rare. For the individual animal, however, these diseases have often a dramatic outcome and many of these diseases presently known are lethal. For several of them the exact pathogenesis is known and DNA-tests are available to confirm the exact diagnosis.

[Hereditary diseases in the horse: II. Polygenetic or multifactorial diseases]. / Erbkrankheiten beim Pferd: II. Polygen vererbte oder multifaktorielle Erkrankungen.

Many of the important diseases of sport and pleasure horses are thought to have a genetic component. The majority of these diseases, however, are multifactorial and are influenced not only by genetics, but also by environmental factors. In this review some of the most important multifactorial diseases are described and the current evidence for a genetic background is discussed.

A region on equine chromosome 13 is linked to recurrent airway obstruction in horses.

UNLABELLED: REASONS FOR STUDY: Equine recurrent airway obstruction (RAO) is probably dependent on a complex interaction of genetic and environmental factors and shares many characteristic features with human asthma. Interleukin 4 receptor a chain (IL4RA) is a candidate gene because of its role in the development of human asthma, confirmation of this association is therefore required. METHODS: The equine BAC clone containing the IL4RA gene was localised to ECA13q13 by the FISH method. Microsatellite markers in this region were investigated for possible association and linkage with RAO in 2 large Warmblood halfsib families. Based on a history of clinical signs (coughing, nasal discharge, abnormal breathing and poor performance), horses were classified in a horse owner assessed respiratory signs index (HOARSI 1-4: from healthy, mild, moderate to severe signs). Four microsatellite markers (AHT133, LEX041, VHL47, ASB037) were analysed in the offspring of Sire 1 (48 unaffected HOARSI 1 vs. 59 affected HOARSI 2-4) and Sire 2 (35 HOARSI 1 vs. 50 HOARSI 2-4), age 07 years. RESULTS: For both sires haplotypes could be established in the order AHT133-LEXO47-VHL47-ASB37. The distances in this order were estimated to be 2.9, 0.9 and 2.3 centiMorgans, respectively. Haplotype association with mild to severe clinical signs of chronic lower airway disease (HOARSI 2-4) was significant in the offspring of Sire 1 (P = 0.026) but not significant for the offspring of Sire 2 (P = 0.32). Linkage analysis showed the ECA13q13 region containing IL4RA to be linked to equine chronic lower airway disease in one family (P<0.01), but not in the second family. CONCLUSIONS: This supports a genetic background for equine RAO and indicates that IL4RA is a candidate gene with possible locus heterogeneity for this disease. POTENTIAL RELEVANCE: Identification of major genes for RAO may provide a basis for breeding and individual prevention for this important disease.

Endoscopic scoring of the tracheal septum in horses and its clinical relevance for the evaluation of lower airway health in horses.

REASONS FOR PERFORMING STUDY: Although endoscopic scoring of the tracheal septum thickness is used as a diagnostic tool for evaluation of lower airway disease, its clinical relevance and reliability have never been critically assessed in the horse. OBJECTIVES: To investigate if septum thickness scores (STS) are reliable and serve as a clinically useful indicator of lower airway disease status and/or inflammation. METHODS: The variance of STS attributable to the horse, observer and changes over time was determined. The distribution of STS in a population of clinically normal horses and correlations of STS with age, gender, as well as mucus accumulation and cell differentials of tracheobronchial secretions and bronchoalveolar lavage fluid were investigated. Effects of altered pulmonary ventilation, induced by different drugs, on STS were assessed. Finally, STS of horses affected with recurrent airway obstruction (RAO) were compared to those of clinically normal horses. RESULTS: Recorded STS showed excellent intra- and satisfactory interobserver agreement Established clinical, endoscopic and cytological measures of lower airway inflammation, i.e. mucus accumulation scores and airway neutrophilia, did not correlate with STS. In horses age > or = 10 years, septum scores were significantly higher (P = 0.022) than in younger horses. Septum thickness scores did not differ significantly between clinically normal and RAO-affected horses both in exacerbation and in remission. Horses with markedly increased breathing effort (i.e. with metacholine- or lobeline hydrochloride-challenge), often differed markedly (up to 1.9 scores), but the average of end-inspiratory and end-expiratory STS did not differ from baseline STS. CONCLUSIONS AND CLINICAL RELEVANCE: Endoscopic STS are a reproducible measure, but STS did not correlate with clinical, endoscopic and cytological findings indicative of RAO or inflammatory airway disease.

Accepting loss: the temporal limits of reciprocity in brown capuchin monkeys.

Delayed reciprocity is a potentially important mechanism for cooperation to occur. It is however rarely reported among animals, possibly because it requires special skills like the ability to plan a loss. We tested six brown capuchin monkeys (Cebus apella) in such skills. Subjects were studied in exchange tasks in which they had to retain a food item for a given time lag before returning it to an experimenter and obtaining a more desirable reward. Experiments showed that the subjects could wait for several minutes when allowed to return only part of the initial item. When required to return the full item intact, however, most subjects could not sustain a time lag longer than 10 s. Although the duration of waiting increased with the amount of return expected by subjects, in most cases it did not extend beyond 20 s even when the eperimenter offered a food amount 40 fold the initial item. The failure of capuchin monkeys to sustain long-lasting waiting periods may be explained by limited self-control abilities. This would prevent them achieving reciprocal altruism.

Specificities in natural cell-mediated cytotoxicity by the cross-competition assay.

The cross-competition assay was applied to natural cell-mediated cytotoxicity in human, mouse and rat systems. The results showed that what appeared to be non-selective effects of natural cytotoxicity were in fact highly specific. Each effector suspension included natural effector cells (N cells) that recognized and reacted specifically with many different antigens on target cells, resulting in overall non-selectivity. The specificity of the reaction for each target cell was demonstrated by the selective inhibition of natural cytotoxicity achieved when competitor cells sharing antigens with the target cell were added. Sharing of common target antigens was demonstrated by selective cross-inhibition which was then used to investigate antigens on target cells.

Decline of natural nonselective cell-mediated cytotoxicity in patients with tumor progression.

Lymphocytes isolated from the blood of patients and healthy donors include a population of cells that destroy target cells in the direct cell-mediated cytotoxic assay with little indication of specificity. This natural reaction is the dominant feature of most cell-mediated cytotoxic tests and, although it appears to be mostly nonselective, it possesses some selective activity. The observed cytotoxicity from these reactions depends mostly on the reactivity of the effector cell; when several effector cells are tested on different target cells, the relative order of activity is usually maintained on the different target cells. When this natural cytotoxicity was analyzed without regard to the type of cancer of the patient or of the target cells, a weak decline in the average reactivity was observed with increasing tumor involvement.