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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 .Die Zucht eines gesunden Pferdes stellt eine Grundvoraussetzung für optimale Leistung dar. Dies wird auch im Zuchtziel des Schweizer Warmblutpferdes spezifisch festgehalten und soll durch eine strenge Selektion der Hengste erreicht werden. Um die Zucht zu optimieren, muss der aktuelle Zustand der Population bekannt sein, was das Ziel der vorliegenden, retrospektiven Studie war. Mittels einer telefonischen Umfrage wurden Daten zum Gesundheitszustand der Schweizer Warmblutpferde im Alter von 6–16 Jahren (mittleres Alter) während ihres bisherigen Lebens gesammelt und deskriptiv aufbereitet. Anschliessend wurden die Heritabilitäten der häufigsten Gesundheitsprobleme geschätzt. Insgesamt konnten zwischen 2016 und 2018 Daten zu 1861 Pferden erhoben werden. Lahmheit (34%), Kolik (22%), Sarkoide (19%) und Mauke (16%) gehörten zu den am häufigsten vorkommenden Gesundheitsproblemen, gefolgt von Rückenproblemen (13%), Husten (10%), Nesselfieber (10%), Kotwasser (9%), Nasenausfluss (8%) und Sommerekzem (4%). Bei 49% der lahmen Pferde war eine Vordergliedmasse betroffen, bei 25% eine Hintergliedmasse, bei 26% beides. 27% der Pferde mit Kolik wurden bereits einmal hospitalisiert und 8% einer Kolikoperation unterzogen. Sarkoide wurden weniger oder kleiner bei 89% der therapierten, aber auch bei 58% der nicht therapierten Pferde. Es konnte ein signifikanter Zusammenhang zwischen Therapie und dem Status der Sarkoide nachgewiesen werden (p .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 ») (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 .Allevare un cavallo sano è un requisito fondamentale per ottenere prestazioni ottimali. Questo è anche specificamente indicato nell’obiettivo per l’allevamento dei cavalli a sangue caldo svizzeri ed esso dovrebbe essere raggiunto attraverso una rigorosa selezione degli stalloni. Per poter ottimizzare l’allevamento, è necessario conoscere lo stato attuale della popolazione; questo era l’obiettivo di questo studio retrospettivo. Via un’indagine telefonica, sono stati raccolti i dati sullo stato di salute dei cavalli a sangue caldo svizzeri di età compresa tra i 6 e i 16 anni (età media) fino ad oggi, e tali dati sono stati elaborati in modo descrittivo. Sono state quindi stimate le ereditabilità dei problemi di salute più comuni. I dati su un totale di 1861 cavalli sono stati raccolti tra il 2016 e il 2018 e tra i problemi di salute più comuni sono stati rilevati zoppia (34%), coliche (22%), sarcoidi (19%) e febbre da fango (16%), seguiti da problemi alla schiena (13%), tosse (10%), orticaria (10%), acqua fecale (9%), secrezione nasale (8%) e prurito dolce (4%). Nei cavalli affetti da zoppia, era stato colpito nel 49% un arto anteriore, nel 25% un arto posteriore e nel 26% entrambi. Il 27% dei cavalli affetti da coliche era già stato ricoverato e l’8% aveva già subito un intervento per le coliche. Nell’89% dei cavalli trattati, i sarcoidi erano meno o più piccoli ma pure nel 58% dei cavalli non trattati. Una relazione significativa è stata dimostrata tra la terapia e lo stato dei sarcoidi (p .

Stella Chapman BVSc (Hons), MSc, MRCVS describes the etiology and management

Redwings' equine veterinary nurse Anna Clarke discusses the problems caused by sweet itch and other seasonal skin irritations

Equine insect bite hypersensitivity (IBH), commonly known as sweet itch or summer eczema, is a frustrating recurrent skin disease in the equine industry involving an immune reaction to the bites of Culicoides spp. midges. To investigate the impact of IBH in the field, an exploratory pilot study was conducted with equine stakeholders in one region of central England. Nine semi-structured, face-to-face interviews were conducted with horse owners and an equine veterinarian. The aim was to gain an understanding of experiences with IBH, and to gauge opinions on the value of the various management strategies horse owners use to control IBH. Awareness of IBH was generally high, particularly in those individuals who had previous experience with the condition. Those with previous experience of IBH commented on the significant effect on daily routines, and the associated cost implications. Most participants supported an integrated approach to hypersensitivity management, and this most commonly involved a combination of physical barriers and chemical repellents, but sometimes included feed supplementation. Overall, attitudes towards IBH suggested that the condition is a notable welfare and economic concern for stakeholders, but veterinary involvement tended to only be in more severe cases. Further research is required in the future to improve understanding, management and potential treatment of this condition.

Insect bite hypersensitivity (IBH) is the most common allergic disease present in horses worldwide. It has been shown that IBH is under genetic control, but the knowledge of associated genes is limited. We conducted a genome-wide association study to identify and quantify genomic regions contributing to IBH in the Dutch Shetland pony population. A total of 97 cases and 91 controls were selected and matched on withers height, coat colour and pedigree to minimise the population stratification. A blood sample was collected from participating Shetland pony mares, their IBH phenotype was scored and the owner filled in a questionnaire. A total of 40 021 single-nucleotide polymorphisms (SNPs) were fitted in a univariable logistic model fitting an additive effect. Analysis revealed no effects of population stratification. Significant associations with IBH were detected for 24 SNPs on 12 chromosomes [-log(10) (P-value) > 2.5]. Odds ratios of allele substitution effects of the unfavourable allele were between 1.94 and 5.95. The most significant SNP was found on chromosome 27, with an odds ratio of 2.31 and with an allele frequency of the unfavourable allele of 0.72 in cases and 0.53 in controls. Genome-wide association studies on additional horse populations are desired to validate the identified associations, to identify the genes involved in IBH and to develop genomic tools to decrease IBH prevalence.

Pruritus is not a disease but a physiological protective alarm system which might react in a pathological destructive fashion, depending on the triggering cause. In horses a frequently suspected reason for destructive pruritus is an allergic disease termed “summer eczema”, “sweet itch”, or “insect bite hypersensitivity”. However, there are numerous alternatives provoking similar clinical symptoms. Additional problems for proper diagnosis and appropriate therapy cause “mixed” forms of diseases: On one hand different causes might occur simultaneously and on the other hand one cause might act via different pathomechanisms. For example: Black flies might provoke strong itching just by their injected saliva when biting (simuliotoxicosis) without any underlying allergy. However, a horse might be allergic against such saliva components. Thus, the intense pruritus is now caused by type I-allergy mechanisms within the framework of a “summer eczema”. This paper compromises two parts. Part 1: Definition and clinical forms of “summer eczema”. Part 2 (to follow in issue 3/2011 of this journal): Pathomechanisms of “summer eczema” including relevant diagnostics plus a list of most of the relevant alternative causes for pruritus and/or “sweet itch”-like symptoms.

Equine summer skin diseases are primarily dominated by insect-related conditions, although outdoor allergens and the sun are responsible for the large proportion of the remaining commonly presented problems. This article reviews the aetiology, presentation and current diagnostic and therapeutic approaches to common insect-induced dermatoses including insect bite hypersensitivity (sweet itch) and harvest mite infestation.

Insect bite hypersensitivity (IBH) is a seasonal allergic skin disease in horses caused by bites of certain Culicoides spp. The aim of our study was to investigate the maternal effect on IBH and to estimate the heritability and repeatability of IBH in the Dutch Friesian horse population. Data consisted of 3,453 Dutch Friesian broodmares with 3,763 visual observations on IBH clinical symptoms scored by 12 inspectors during organized foal inspections in 2004 and 2008. Nine percent of the mares (n = 310) were scored in both years. Mares descended from 144 sires and 2,554 dams and 26.2% of the dams (n = 669) had more than 1 offspring in the data set (range: 2 to 6). Insect bite hypersensitivity was analyzed as a binary trait with a threshold animal model with and without a maternal effect, using a Bayesian approach. Observed IBH prevalence in Dutch Friesian broodmare population was 18.2%. Heritability on the liability scale was 0.16 (SD = 0.06); heritability on the observed scale was 0.07; and repeatability was 0.89 (SD = 0.03). Maternal effect was 0.17 (SD = 0.06) and significantly differed from zero, although the animal model without a maternal effect fitted the data better. These results show that genetic and permanent environmental factors affect IBH in Dutch Friesian horses. The dam affected the IBH development of her offspring through an additive genetic influence but also by being part of their rearing environment.

This work aimed to study the prevalence of different skin q[fections in equine and the risk factors influencing it during one year from February 2009 to February 2010. Out of 3014 examined equine, 267 (8.86%) were s4ffering from skin diseases. The prevalence rate was dermatophytosis 3.52%, Sweet itch 2.19%, Mange 1.46%, bac­ terial dermatitis 0.36% , cutaneous pythiosis 0.3%, cutaneous habronemiasis 0.27%, vitiligo 0.2%, allergic dermatitis 0.2%, urticaria 0.17%, tick allergy 0.13% and equine warts 0.07%. Dermatophytosis occurred with high incidence rate in Arabian horses al­ though good hygiene and management comparing to drqft horses which showed spo­ radic cases. The disease occurred more commonly in younger ages and infall season. The mycotic cultivation revealed 75 dermatophyte isolates. The most common isolated dermatophyte was T.equinum 53.3%followed by M.canis 29.3% and other dermatoph­ ytes were isolated as M.gypseum 9.3%, T.mentagrophytes 5.3%, T.tonsurans 1.3% and M.audouinii 1.3%. Sweet itch occurred with higher incidence in horses at summer sea­ son and the number of horses q[fected with sweet itch rose with increasing age. Mange was diagnosed mostly in draft horses and donkeys with high incidence in win­ ter. No age difference was observed in the occurrence of mange in equine. Psoroptic mange was the most common cause of mange in equine

We postulated that all horses exposed to the bites of Culcoides (midges) would have an antibody response to the antigen secreted in Culcoides saliva, but that IgE antibody would be restricted to allergic individuals. Using immunohistology on sections of fixed Culicoides, we have demonstrated the presence of antibodies in horse serum which recognise Culicoides salivary glands. Antibodies were detected in the serum of horses with insect dermal hypersensitivity and in the serum of normal horses exposed to Culicoides bites. In contrast, no antibodies were detected in serum from native Icelandic ponies which had not been exposed to Culicoides. Anti-salivary gland IgG antibodies were detected in serum from both allergic and healthy horses exposed to Culicoides. IgE antibodies were only detected in horses with signs of insect dermal hypersensitivity, they were not found in serum of healthy controls nor in the serum of horses with a history of hypersensitivity but in remission at the time of sampling. Using western blotting we confirmed the presence of antibodies to Culicoides antigens and demonstrated that individual horses react to different numbers of antigens. This paper demonstrates the ability of serum from allergic horses to detect Culcoides antigens and will enable further studies to isolate and characterise the allergens.

Intradermal tests using a Culicoides nubeculosus extract have proven unreliable for diagnosis of equine insect bite hypersensitivity (IBH) in the Netherlands. The aim of this study was to evaluate the diagnostic value of an extract derived from the Dutch species C. obsoletus and C. pulicaris. Thirteen pairs of horses were tested, each pair consisting of one horse with IBH and the other a healthy control. Each horse was injected intradermally with 0.1 mL of three concentrations of Culicoides whole body extract (1 : 1000 w/v, 1 : 10,000 w/v and 1 : 25,000 w/v), histamine solution (0.01 mg/mL, positive control) and phosphate-buffered saline (negative control). Skin responses were evaluated after 30 min and at 1, 4 and 24 h. At all time points the absolute wheal diameter elicited by Culicoides extract 1 : 1000 w/v was significantly larger (P

The aims of this study were to determine (1) which species of Culicoides is most commonly attracted to horses, (2) whether horses suffering insect hypersensitivity attract more Culicoides spp. than unaffected horses, and (3) the times when Culicoides spp. are most active. Horses affected by insect hypersensitivity and unaffected horses were placed inside mosquito netting tents for 30 min at different times of the day. All Culicoides spp. trapped inside the tents were collected and identified. C. obsoletus was the most common species found, followed by C. pulicaris. Healthy horses attracted slightly more midges than horses that were affected with insect hypersensitivity. All of the Culicoides species were most active at sunset, less so at sunrise and very few or no midges were trapped in the afternoon or at night.

An Internet-based questionnaire among horse owners was carried out to identify factors affecting the incidence of insect bite hypersensitivity (IBHI) among horses in the Netherlands. Information was obtained for 794 horses of various breeds, but the breed distribution was not representative for the Dutch horse population. Of the horses for which information was available, 56% suffered from IBH and 44% did not. The most common clinical symptoms were pruritus, scaling, and hair loss, occurring mainly at the base of the tail and along the mane. Breed, age, region (and local habitat), stabling, type of bedding in the stable, use of the horse, deworming frequency, and season were associated with significant differences in IBH incidence. Knowledge of the factors influencing the incidence of IBH may make it possible to reduce the number of animals affected and help alleviate symptoms in affected horses.

Ed Whittle, MA, VetMB, MRCVS, technical consultant at Elanco Companion Animal Health discusses the perennial trauma of sweet itch

The immunological mechanisms explaining development of an allergy in some individuals and not in others remain incompletely understood. Insect bite hypersensitivity (IBH) is a common, seasonal, IgE-mediated, pruritic skin disorder that affects considerable proportions of horses of different breeds, which is caused by bites of the insect Culicoides obsoletus (C. obsoletus). We investigated the allergen-specific immune status of individual horses that had either been diagnosed to be healthy or to suffer of IBH. Following intradermal allergen injection, skin biopsies were taken of IBH-affected and healthy ponies and cytokine expression was determined by RT-PCR. In addition, allergen-specific antibody titers were measured and cytokine expression of in vitro stimulated, allergen-specific CD4 T-cells was determined. 24 hrs after allergen injection, a significant increase in mRNA expression of the type-2 cytokine IL-4 was observed in the skin of IBH-affected Shetland ponies. In the skin of healthy ponies, however, an increase in IFNγ mRNA expression was found. Analysis of allergen-specific antibody titers revealed that all animals produced allergen-specific antibodies, and allergen-specific stimulation of CD4 T-cells revealed a significant higher percentage of IFNγ-expressing CD4 T-cells in healthy ponies compared to IBH-affected ponies. These data indicate that horses not affected by IBH, in contrast to the so far established dogma, are not immunologically ignorant but have a Th1-skewed allergen-specific immune response that appears to protect against IBH-associated symptoms. To our knowledge this is the first demonstration of a natural situation, in which an allergen-specific immune skewing is protective in an allergic disorder.

In-vitro the transport of HCO3- in the mucosal–serosal direction (absorption), Jms, was studied across the isolated epithelium of sheep omasum. The conventional Ussing chamber technique was combined with the pH-stat method. The mucosal side of the tissues was incubated with a buffer solution of 50 mmol∙l-1 HCO3- and gassed with 10% CO2. The buffer solution of the serosal side was HCO3- and buffer free. The pH (7.4) of the serosal side was kept constant by titration of H2SO4. The amount of titrated H2SO4 was considered as amount of transported HCO3-. a) The current model of anion transport across the omasal epithelium with two anion exchangers in series in the apical and basolateral membrane was confirmed. The omasal epithelium has the capability to transport HCO3- in both directions according the applied ion gradients. However, the flux from mucosal to serosal side was significantly larger than the transport in the reversed direction. b) The transport of HCO3- depends on the activity of Na/H exchanger (NHE3) in the apical membrane. Inhibition of NHE3 by mucosal amiloride (1 mmol∙l-1) or reduction of mucosal Na+ concentrations reduced HCO3- transport significantly. It is concluded that the NHE3 mediated extrusion of H+ is of predominant importance for regulation of the intracellular pH, pHi, and hence HCO3- transport. c) The manipulation of pHi by transport of SCFA (uptake of the undissociated SCFA in the mucosal- serosal direction) reduced HCO3- transport. However, this effect was only of minor importance in tissues from concentrate-fed sheep. d) Inhibition of carbo-anhydrase by carboxyzolamide (0.1 mmol∙l-1) caused a significant decrease of HCO3- transport. e) The suggested anion exchanger of HCO3- transport was examined by using levetiracetam, a Na+-coupled Cl-/HCO3 exchanger inhibitor. The addition of levetiracetam (1 mmol∙l-1) failed to produce a reduction of the HCO3- transport rates. f) It is concluded that the transport of HCO3- is mediated by two anion exchangers in series and that the regulation of pHi is of paramount importance of undisturbed HCO3- transport. There is evidence for adaptation of the omasal epithelium to diet. g) It is proposed that the absorption of HCO3- should be included in the discussion of the pathogenesis of displaced abomasum., In-vitro wurde der Transport von HCO in der mucosal3- serosalen Richtung, J, (Absorption) msdurch das Epithel des Blättermagens von Schafen untersucht. Die konventionelle Ussing Kammer Methode wurde mit der pH-stat Technik kombiniert. Die mucosale Seite des Epithels wurde mit einer Pufferösoung mit 50 mmol∙l-1 HCO3- inkubiert und 10% CO2 begast. Die Pufferlösung der serosalen Seite enthielt kein HCO3- und keinen Puffer. Der pH (7.4) der serosalen Seite wurde konstant gehalten duch die Titration mit H2SO4. Die Menge der titrierten HSO wurde als transportierte Menge HCO,J, angesehen. 243-ms a. Die erhaltenen Ergebnisse bestätigen das zur Diskussion vorgeschlagene Modell des Aniontransports durch das Epithel des Blättermagens vom Schaf: Der Transport wird durch zwei Anionenaustauscher in Serie in der apikalen und basolaterlaen Membran vermittelt. Das Epithel ermöglicht den Transport von HCO3- in beiden Richtungen entsprechend den vorgegebenen Gradienten. Der Transport von Jms ist jedoch signifikant höher als in der entgegengesetzten Richtung, Jsm. b. Der Transport von HCO3- wird durch die Aktivität des Na/H Austauschers (NHE3) in der apikalen Membran beeinflusst. Eine Hemmung des NHE3 mit Amilorid (1 mmol∙l-1) oder Verringerung der mukosalen Na Konzentration reduzieren den HCO3- Transport signifikant. Diese Effekte lassen die Schlussfolgerung zu, dass der Heraustransport von H+ mit Hilfe des NHE3 von großer Bedeutung für die Regulation des intrazellulären pH, pHi, und als Konsequenz auch für den HCO3- Transport ist. c. Die Beeinflussung des pH durch SCFA (Aufnahme der undissoziierten SCFA (J) imsverringert den HCO3- Transport. Diese Wirkung ist jedoch von geringer Bedeutung für den HCO3- Transport in Geweben von Schafen, die mit Kraftfutter gefüttert wurden. d. Die Hemmung der Carboanhydrase mit Ethoxyzolamid (0.1 mmol∙l-1) verursacht eine signifikante Abnahme des HCO3- Transports. e. Levetiracetam hemmt den Na-gekoppelten Cl/HCO. Die muksoale Zugabe -3-dieses Inhibitors (1 mmol∙l-1) beeinflusste den HCO3- Transport nicht. f. Die Ergebnisse lassen die Schlussfolgerung zu, dass der HCO Transport durch 3-zwei Anionenaustauscher in Serie in der apikalen und basolateralen Membran vermittelt wird und maßgeblich vom pHi beeinflusst wird. Es liegen Hinweise vor, dass Adaptationsvorgänge in Abhängigkeit von der Fütterung (Kraftfutter) erfolgen und den HCO3- Transport stabilisieren. g. Es wird vorgeschlagen, dass der Transport von HCO3- und dessen Beeinflussung in die Diskussion der Pathogenese der Labmagenverlagerung einbezogen wird.

Das Sommerekzem des Pferdes ist eine weit verbreitete Erkrankung, welche von hoher wirtschaftlicher und klinischer Bedeutung ist. Ziel dieser Studie war es, in einer rasseübergreifenden, deutschlandweiten Untersuchung neue Daten zum Sommerekzem auf Grundlage epidemiologischer und managementbezogenen Faktoren zu erheben und die bestmögliche Therapiemethode zu erfassen. Dazu wurde innerhalb der Bundesrepublik Deutschland, Österreich und der Schweiz eine schriftliche Befragung der Besitzer von Pferden mit Sommerekzem anhand eines Fragebogens durchgeführt. Der Rücklauf auswertbarer Datensätze betrug 404. Mit Hilfe univariater Verfahren wurden dann Faktoren statistisch analysiert, die im Verdacht stehen, Einfluss auf das Auftreten und die Symptomatik des Sommerekzems beim Pferd zu haben. Am häufigsten kamen dabei verteilungsgebundene Prüfverfahren wie der t-Test und der F-Test zum Einsatz. Zusätzlich wurden auch der Chi-Quadrat-Test (χ²-Test) und die Regressionsanalyse angewendet. Die Ergebnisse der vorliegenden Studie zeigten, dass in der hier untersuchten Studienpopulation von 404 Pferden Wallache mit 51 % im Vergleich zu Stuten und Hengsten sowohl am häufigsten vom Sommerekzem betroffen waren als auch die stärkste Symptomatik aufwiesen (p < 0,02). Das durchschnittliche Erkrankungsalter der Pferde dieser Studie lag bei 5,7 Jahren. Innerhalb der Studienpopulation zeigte sich ein signifikant früherer Erkrankungsbeginn bei Hengsten (um 3,0 Jahre) im Vergleich zu Wallachen (p = 0,019). Wallache erkrankten wiederum signifikant später als Stuten, und zwar um 1,7 Jahre (p = 0,001). Die meisten Pferde der Studie hatten eine dunkle Fellfarben (50,9 %). Auch Füchse waren mit knapp 20 % häufig vertreten. Schimmel und Apfelschimmel erkrankten in der untersuchten Population mit einer signifikant geringeren Symptomatik als Pferde anderer Fellfarben (p < 0,05). Bei Falben und isabellfarbenen Pferden der Studienpopulation zeigte sich dagegen die stärkste klinische Symptomatik des Sommerekzems (p < 0,05). Der größte Anteil der Studienteilnehmer waren Warmblutpferde (69 %), gefolgt von Kaltblutpferden mit 21 % und Vollblütern mit 7 %. Bei der differenzierten Darstellung der Pferderassen bildeten Shetlandponys, Islandpferde und Haflinger als Robustpferderassen mit insgesamt 31,3 % ebenfalls einen großen Anteil der Stichprobe. Die Kaltblüter zeigten in der Studie die schwersten Symptome des Sommerekzems. In dieser Studie bestanden zudem Zusammenhänge zwischen dem Ekzemgrad und dem Weidegang der Pferde. Permanent auf der Weide gehaltene Pferde erkrankten signifikant früher am Sommerekzem als andere Pferde. Die Analyse der Fütterung der Pferde ergab, dass mit Kraftfutter (Hafer und/oder Müsli) gefütterte Pferde ein milderes Krankheitsbild entwickelten als nicht mit Kraftfutter gefütterte Pferde (p= 0,015). Bei der Analyse des Entwurmungsstatus zeigten Pferde, die nicht regelmäßig entwurmt wurden, eine schwerere Symptomatik als Pferde, die einmal im Jahr ein Entwurmungsmittel appliziert bekamen (p < 0,02). Körperregionen, an denen das Sommerekzem seinen Beginn zeigte, waren in der untersuchten Population vorherrschend der Mähnenkamm und der Schweifansatz, gefolgt vom Unterbauch. Trat das Sommerekzem zuerst am Unterbauch auf, war die Symptomatik später schwerwiegender. Die Veränderungen in Haut- und Haarkleid erstreckten sich später bei dem Großteil der Pferde auf den Mähnenkamm (91,3 %) und den Schweifansatz (89,4 %). Erstaunlicherweise waren darüber hinaus bei einer großen Anzahl an Pferden Areale wie das Gesicht (48 %), die Ohren (46,5 %), der Widerrist (33,7 %), der Hals (32,2 %) und die Innenschenkel (23,5 %) betroffen. Zum Zeitpunkt der Studie litten 99 % der Pferde unter Juckreiz, davon 76,5 % mit starker Ausprägung. Zudem traten Symptome wie haarlose Stellen im Fell (87 %) und Schuppenbildung (80 %) auf. Weiterhin konnten sowohl blutige Krusten (74 %) als auch Hautverdickungen (68,1 %) als Zeichen eines chronischen Geschehens festgestellt werden. Hier fiel auf, dass sich mit steigendem Alter der Pferde das Krankheitsbild signifikant verschlechterte. Auch mit zunehmender Erkrankungsdauer verschlimmerte sich die Ausprägung des Sommerekzems deutlich. Des Weiteren wurden im Fragebogen Details zum Kauf betroffener Pferde untersucht. Das Hauptaugenmerk lag hierbei auf der Hautbeschaffenheit zum Zeitpunkt des Kaufs und den Ergebnissen der Kaufuntersuchung. Erstaunlicherweise zeigten 41,4 % der untersuchten Pferde schon zum Zeitpunkt des Kaufs Symptome des Sommerekzems. 32,4 % der Pferde zeigten beim Kauf bereits Juckreiz und 30 % wiesen bereits beim Kauf haarlose Stellen im Haarkleid auf. Pferde, die zum Zeitpunkt des Kaufs bereits eine große Zahl an haarlosen Stellen im Fell aufwiesen erkrankten später signifikant stärker am Sommerekzem als Pferde, die keine oder lediglich wenig haarlose Stellen zeigten. Noch deutlicher verhielt es sich mit dem Juckreiz. Hier hatten Pferde, welche beim Kauf mit starkem Pruritus aufgefallen waren, später mit einen signifikant schwereren Krankheitsbild zu kämpfen als Pferde mit keinem, leichtem oder sogar mittelstarkem Pruritus (p < 0,05). Nur bei 25,1 % der Studienpferde wurde eine Kaufuntersuchung durchgeführt, jedoch stellte der Tierarzt lediglich bei 3,5 % dieser Pferde einen Hautbefund fest. Bei 27,5 % berichteten zudem die Vorbesitzer von bereits bestehenden Hautproblemen. Die Analyse der Daten zeigt, dass bereits bei einigen Pferden dieser Studie zum Zeitpunkt des Kaufs Hautprobleme eine große Rolle spielten. 9,5 % der Pferde der Studie hatten eine Vorerkrankung. Darunter litten 3,8 % der Pferde an einer Allergie, angefangen von Heu- oder Stauballergie (2,8 %), bis hin zu Hausstaubmilbenoder Futtermittelallergien. An einer Lungenerkrankung waren insgesamt 2,0 % der Pferde (n = 8) erkrankt Die Ergebnisse der vorliegenden Studie zeigen einen guten Überblick über den Erfolg der gängigsten Therapeutika und Behandlungsmethoden des Sommerekzems in der hier untersuchten Population. Grundsätzlich wurde festgestellt, dass als Folge der Behandlung des Sommerekzems bei 72,8 % der Pferde eine Besserung des Krankheitsbildes auftrat. Den besten Effekt, mit einer Erfolgsquote von 70,3 %, erzielte die Nutzung einer Ekzemerdecke. Auch Cremes konnten bei 40 % der behandelten Pferde der Studie eine positive Wirkung erzielen. Im Gegensatz hierzu brachten Homöopathika, Repellentien und die Eigenbluttherapie keine deutliche Verbesserung des Krankheitsbildes mit sich. Die Desensibilisierung brachte bei 5 Pferden der Studienpopulation eine Verbesserung der Symptomatik. Die Studie zeigt somit, dass die wirksamste Prävention und Therapie des Sommerekzems bei der Studienpopulation in der Minimierung der Allergenexposition und der damit verbundenen Reduktion der Insektenbelastung lag. 85,1 % der Studienteilnehmer berichteten über eine insgesamt starke Insektenbelastung. Mit steigender Gnitzen- und/oder Bremsenbelastung verschlechterte sich die Symptomatik des Sommerekzems signifikant (p < 0,00). Die Erkenntnisse dieser Studie liefern neue, rasseübergreifende Daten über die Entstehung, Ausprägung und Behandlung des Sommerekzems bei betroffenen Pferden einer Stichprobe mit 404 Studienteilnehmern in Deutschland. Limitationen dieser Studie liegen vor allem in der fehlenden Bezugsgröße zu der Gesamtpferdepopulation in Deutschland. Um Rückschlüsse auf die Gesamtpopulation in Deutschland ziehen zu können, bedarf es einer Kontrollgruppe. Erst dann sind konkrete Aussagen zur Epidemiologie des Sommerekzems zulässig. Weitere Verzerrungen der Studie liegen in der Subjektivität der Pferdebesitzer sowie der Auswahl der Stichproben. Es besteht die Möglichkeit, dass vermehrt Besitzer stark betroffener Pferde an der Studie teilgenommen haben. Da es sich um eine rein schriftliche Befragung handelt, kann die Einschätzung der Besitzer vor allem bei Determinanten, wie der Schwere der Symptomatik und der Insektenbelastung sehr unterschiedlich ausfallen. Zudem liegt den Ergebnissen dieser Studie eine einmalige Datenerhebung zugrunde, wodurch bei einigen Fragestellungen lediglich eine Momentaufnahme dargestellt wird. Ansätze zur Verbesserung des Studiendesigns bestehen in der Kombination aus einer schriftlichen Befragung der Besitzer und einer einheitlichen Untersuchung der Pferde durch einen Tierarzt. Zudem wäre es sinnvoll den Verlauf der Erkrankung über mehrere Jahre einheitlich zu kontrollieren. Hierfür sollte ein Fragebogen konzipiert werden, der mehrmals im Jahr vom Pferdebesitzer ausgefüllt werden muss und durch Bildmaterial zur Dokumentation der Symptomatik des Sommerekzems ergänzt wird., Sweet itch in horses is a common disease of great economic and clinical importance. The aim of this study was to examine the influence of epidemiological- and management-related factors on the clinical signs of sweet itch in a multi equine racial, Germany-wide investigation. Furthermore, the aim was to find the best method of treatment. First, a survey was conducted using questionnaires. There was a return of 404 evaluable records. Those factors meant to have an effect on the incidence of sweet itch in horses, were then statistically analyzed using univariate and bivariate methods. The most common distributionbased test methods such as the t-test and F-test were utilized, as well as the chi-square test (χ²) test and the regression analysis. The results of the present study show that compared to stallions, geldings were most affected by sweet itch, as they showed the strongest symptoms (p < 0.02). The average age of onset of the horses was 5.7 years. Differentiations by gender show a significantly earlier onset of stallions (by 3.0 years) compared to geldings. Geldings show symptoms significantly later than mares, namely by 1.7 years. It was also found that the incidence of sweet itch increased in horses of a darker color (50.9 %). It was also clear that chestnuts were represented with nearly 20 %. Gray and dapple gray showed milder symptoms than other coat colors (p < 0.05). Buckskin and palomino horses showed the most severe symptoms of sweet itch of all coat colors (p < 0.05). Furthermore, warm blood horses (69 %) had a high disease rate, followed by draft horses (21 %) and Thoroughbreds (7 %). With the differentiated representation of horse races Shetland's ponies, Icelandic horses and Haflinger as robust horse races with a total of 31.3 % form a big portion of the horses with summer eczema. Considering the severity of summer eczema in relation to race, draft horses had the strongest symptoms of sweet itch. Furthermore, there were correlations between the degree of eczema and the grazing of horses. Horses, held on pasture 24 hours a day were affected by sweet itch significantly earlier than other horses. In the present study, no significant influence on summer eczema could be detected in the analysis of the attitude of the horse (p > 0.05). The analysis of the feeding has shown that horses fed with concentrated feed (oats and/or muesli) showed milder symptoms than horses, which were not fed with concentrated feed (p = 0.015). The analysis of the status of deworming demonstrated that horses that have not been dewormed regularly, showed more severe symptoms than horses that were dewormed once a year (p < 0.02). Regions of the body where sweet itch appeared in the early stages were predominantly the mane and tail, followed by the abdomen. In later onset cases, horses would show symptoms along the linea alba. At the time of this study, the majority of the horses showed symptoms in the mane (91.3 %) and tail (89.4 %). Amazingly, there were also a large number of horses that had been affected in areas as the face (48 %), ears (46.5 %), the withers (33.7 %), neck (32.2 %) and the inner legs (23.5 %). Furthermore, results show that when withers, trunk or inner legs were affected, the disease had already progressed to a significant stage. At the time of this study 99 % of the horses suffered from itching, 76.5 % with strong expression. Furthermore, the horses showed symptoms such as bald areas (87 %) and dandruff (80 %). Bloody crusts (74 %) and skin thickening (68.1 %) were seen as a sign of a chronic affection. With increased age of the horses symptoms of sweet itch worsened. There seems to be a significant correlation between increased duration and worsened symptoms in this disease. Details were focused of the purchase of the horse. The main attention lay on the skin at the time of the purchase and the purchase investigation. These aspects were analyzed because the horses may already have shown certain skin changes at the time of the purchase but these had not been diagnosed as summer eczema. Surprisingly 41.4 % of the horses already showed symptoms of the summer eczema at the time of the purchase. Itching manifested at 32.4 % of the horses and in turn hairless areas already showed 30 % at the purchase in the coat. The horses which already had a big number at hairless places in the coat at the time of the purchase later showed significantly stronger symptoms of summer eczema than horses who showed none or merely few hairless areas. Even more clearly it behaved with the itching of the horses. Horses who had strong pruritus at the time of the purchase, later showed a significantly heavier clinical picture than horses with none, light or even medium strong pruritus (p < 0.05). With 25.1 % of the horses a purchase investigation was carried out, however, the veterinarian ascertained skin findings merely with 3.5 % of these horses. 27.5 % of the previous owners reported already existing skin problems. The analysis of the data shows that skin problems played a big role at the time of the purchase. Whether or not this was a deliberate deception on the side of the selling owner cannot be excluded. Furthermore 9.5 % of the horses in the study showed a preexisting illness. 3.8 % of these horses had an allergy, starting from hay- or dust-allergy (2.8 %), dust-mites or feed allergens. A total of 2.0 % of the horses (n = 8) fell ill with a lung illness. The results of this study show the success of the most common drugs and treatment methods of sweet itch. In principle, it was noticed that a recovery of the syndrome appeared as a result of the treatment of the summer eczema in 72.8 % of the horses. The highest success rate of 70.3 % was achieved by using an eczema blanket. The use of creams was valued at an acceptable success of 40 %. In contrast, the use of homeopathics, repellents and autohaemotherapy showed no significant improvement of the disease. Desensitization induced an improvement of the clinical signs of summer eczema of 5 horses. Furthermore, there were associations between the exposure to insects and the severity of the symptoms of sweet itch in horses. The analysis of the data showed that 85.1 % of the owners reported a strong insect load. The higher the midges and/or brake load, the worse the symptoms. The study therefore showed that the best prevention and treatment of sweet itch in horses is the minimization of allergen exposure and the associated reduction of the insect load. The findings of this study show for the first time a representative, multi-breeding overview of the etiology, severity and treatment of summer eczema in examined horse population. All in all it was noticed that in 72.8 % of horses suffering from sweet itch, those treated showed an improvement in symptoms. The best effect, with 70.3 % positive outcome, was visible with the use of a blanket. Creams showed an improvement in 40 % of the treated animals. The use of homeopathy, repellants as well as autoheamotherapy did not show significant improvement of the symptoms. In 5 case studies desensitization proved efficient. The study shows that the most effective prevention and therapy of sweet itch is minimization of explosion towards the allergen. 85,1 % of the participants in the study recalled an increase of Insects. The higher the insect load, the worse the symptomatic of sweet itch (p < 0,00). This study provides new insight on the development, manifestation and treatment of sweet itch in different horse breeds. The random sample consisted of 404 participants throughout Germany. Limiting factor to this study was the missing reference toward the entire horse population in Germany. To be able to draw conclusions about the entire horse population one would need a control group. Only then would a concrete statement about the epidemiology of sweet itch be valid. Furthermore the subjectivity of the horse owners as well as the sample choice has to be taken under advisement. There is a possibility that predominantly owner of horses affected more severely with sweet itch participated in the study. As it is a purely written questionnaire the assessment of the horse owner concerning the severity of symptoms as well as the insect load may vary greatly. A combination of a written questionnaire as well as an examination by a veterinarian may lead to more thorough result.. Also evaluating the progression of sweet itch over several years would be useful. A questionnaire should be designed that should be filled out by the owner more than once a year to which pictures documenting the symptomatic of sweet itch should be added.

Intradermal injection of a Culicoides antigen extract (CAgX) induces T lymphocyte and eosinophil accumulation in the skin of horses with sweet itch. Blood mononuclear ( BMN ) cells from normal ponies proliferate when stimulated by mitogen (phytohaemagglutinin, PHA ) or antigen (tetanus toxoid, TT ) and, as shown here, release soluble factor(s) that induce eosinophil adherence. CAgX also caused concentration dependent proliferation of BMN cells from sweet itch and normal ponies [stimulation index: 29 (13) and 17 (7) for BMN cells from sweet itch and normal ponies, respectively during the active phase of disease; 4 μg protein ml−1CAgX; 168 h]. A heat labile factor(s) which caused eosinophil adherence was also released [sweet itch ponies: 6.0 (1.6) per cent adherence versus 1.3 (0.4) per cent; normal ponies: 6.6 (0.5) per cent adherence versus 0.9 (0.1) per cent for supernatants from CAgX (4 μg protein ml−1; 48 hours) stimulated versus unstimulated BMN cells, respectively]. These results suggest that soluble proteins released from T lymphocytes could affect eosinophil function in the lesional skin of sweet itch horses.

The allergy desensitization technique, known as "intradermal neutralization", was originally described by Dr H. Carlton-Lee. The procedure was later extended and modified by Professor J. B. Miller of Mobile, Alabama and currently is used extensively for treating allergic disease in humans, especially in the USA, but also in Canada, the UK and Australia. The technique has been shown in many clinical papers to be effective in humans as a means of desensitizing both food and biological inhalant allergens. It is also effective in chemical sensitivity. Although there have been sporadic reports of successful use in horses and other animals, this is the first to show a marked effect in equine asthma, otherwise known as chronic obstructive pulmonary disease or heaves. The results in equine urticaria are even better and there appears to be benefit in some cases of headshaking (equine rhinitis). The number of horses treated for sweet itch was too small to draw any conclusion. The positive effects shown in this stud...

Bei dem Sommerekzem der Pferde kommt es aufgrund einer Überempfindlichkeitsreaktion auf Insektenspeichel, der beim Saugakt übertragen wird, zu klinischen Symptomen wie z.B. Juckreiz, Alopezie und Hautläsionen. Dies führt zu einer Gebrauchsminderung der betroffenen Pferde bis zu 50% während der Flugzeiten der Insekten von ca. März bis Oktober. Zusätzlich haben diese Pferde einen hohen Leidensdruck. Die Behandlung der Erkrankung ist sehr individuell und alle Therapien sind lediglich Versuche, auf die jedes betroffene Pferd anders anspricht. Sie bewirken teilweise eine Reduzierung der klinischen Symptome, doch gibt es derzeit keine Heilung für das SE. Diese Arbeit basiert auf einem neuartigen Therapieansatz für das Sommerekzem beim Pferd. Es wurde das als Therapeutikum bei menschlichen Autoimmunerkrankungen bekannte TACI-Ig für das Pferd entwickelt. Damit sollen die Zytokine BAFF und APRIL, die wichtige Regulatoren für die Reifung, Funktion und das Überleben von B-Zellen sind, gebunden werden um deren Wirkung auf die B-Zellen zu neutralisieren. Dadurch wird die Apoptoserate der B-Zellen erhöht. Die Reifung der B-Zellen zur Plasmazellen bleibt aus und es werden keine Immunglobuline produziert. Das wiederum verhindert die Freisetzung von Entzündungsmediatoren aus Mastzellen. Mit dem equinen TACI-Ig (eTACI-Ig) soll auf das Immunsystem des Pferdes eingewirkt werden, um die relevanten Reaktionsmechanismen für die Entstehung und Unterhaltung des Sommerekzems zu beeinflussen und damit den Ausbruch der Erkrankung zu verhindern. Für die Entwicklung des eTACI-Igs wurde der extrazelluläre Teil des equinen TACI aus der DNA des Pferdes herausamplifiziert und an einen FC-Teil eines equinen Immunglobulins gebunden. Im Anschluss wurde die Proteinbiosynthese von eTACI-Ig durchgeführt. Das nun vorliegende Protein wurde in einem in vitro Test-System auf seine Bindungsfähigkeit geprüft. Dafür wurden die equinen Zytokine eBAFF und eAPRIL produziert. Mit der Hilfe dieser beiden Zytokine konnte eine Bindung an eTACI- Ig nachgewiesen werden und liefert damit den Beweis für die Funktionsfähigkeit von TACI-Ig. In dem erfolgten ELISA konnte demnach bewiesen werden, dass das entwickelte eTACI-Ig an eBAFF und eAPRIL bindet, womit die Funktionalität des eTACI-Ig in vitro nachgewiesen wurde. Ziel dieses Projektes war es mit Hilfe der Kenntnissen zum Immunsystem des Pferdes und zum Krankheitsmechanismus des Sommerekzems, eine neuartige Therapie durch eTACI-Ig zu entwickeln und damit einer Linderung und/ oder Heilung des Sommerekzems zu forcieren. Um die richtige Funktionsweise der Therapie im lebenden Organismus zu verifizieren, müssen jedoch einige Vorversuche ausgeführt werden. Es empfehlen sich ex-vivo Tests, also Testreihen mit frischem Pferdeblut um eine Wirkung des eTACI-Igs auf die verschiedenen Zellen (z.B. B-Zellen, Plasmazellen) und die Immunglobuline zu untersuchen. Auch müssen Analysen stattfinden, die Einblick auf Wirksamkeit, Verträglichkeit und Dosierung des eTACI-Ig im Pferd geben. Trotz der Schwierigkeiten und hohen Kosten der Produktion von großen Mengen eTACI-Ig zur Behandlung des Sommerekzems sind finale Tests im Pferd nötig. Für die Zukunft könnte das eTACI-Ig in der Pferdemedizin für den Einsatz beim Sommerekzem ein interessantes Medikament werden, denn es lässt auf eine Therapie mit Aussicht auf Heilung hoffen, wodurch vielen betroffenen Pferden ein normales und unbeschwertes Pferdeleben ermöglicht werden könnte und vielleicht lässt es sich für weitere allergisch bedingte Erkrankungen beim Pferd einsetzten., Summer eczema in horses represents a seasonal recurrent allergic dermatitis to the insect’s salivary proteins of Culicoides biting midges. Clinical symptoms of affected horses include itching, alopecia and skin lesions, resulting in a diminished usability of up to 50% during the flight time of the insect from March to October. In addition, horses with summer eczema suffer from a lot of strain. Therapeutical treatment can be very individualans all therapies are approach only and every horse can react distinctly. State of the art therapy can only reduce clinical symptoms, yet a cure of summer eczema is still to be found. This work is thought to found a new therapeutical approach for the treatment of summer eczema in horse. On the basis of a therapeutical called TACI-Ig used to remedy human autoimmune diseases a strategy was developed to transfer the effective mechanism to the equine model. TACI-Ig neutralizes its pro-inflammatory cytokine ligands BAFF and APRIL, resulting in impaired maturation, functioning and survival of B cells, increases the apoptosis rate of these cells and thereby inhibiting their development into B cells as well as the consecutive production of immunoglobulins. As a result, no inflammatory molecules will be released from mast cells. A systemic administration of equine TACI-Ig (eTACI-Ig) could inhibit mechanisms relevant for development and sustentation of this disease. In this study eTACI-Ig was developed via PCR amplificationthe of the extracellular part of TACI from horse DNA and coupling it to the FC region of an equine immunoglobulin. The resulting fusion protein eTACI-Ig was tested for functionality by means of neutralizing its ligands equine BAFF and APRIL, which were also produced in the context of this work. ELISA tests clearly showed binding of eTACI-Ig to eBAFF and eAPRIL, proving the functionality of the newly synthesized fusion protein in vitro. Goal of this project was to transfer knowledge of the immune system of horses and the disease mechanisms to an effective approach for therapeutical treatment and potential cure of summer eczema by eTACI-Ig. Further ex and in vivo functionality tests are needed, e.g. the ex vivo study of its impact on various cell types and equine immunoglobulins on the base of fresh horse blood. Additionally, in vivo efficacy, dose responses and tolerance need to be determined. Although, production of big amounts of TACI-Ig can be difficult and expensive, its necessary in order to finally treat summer eczema systemically in horses. A successful treatment of summer eczema with eTACI-Ig could potentially give rise to treatment and curation of other allergic illnesses in horses and would be a fundamental break-through in horse medical science.

Insect bite hypersensitivity (IBH) is a seasonal allergic skin disease in horses caused by bites of certain Culicoides spp. The aim of our study was to investigate the maternal effect on IBH and to estimate the heritability and repeatability of IBH in the Dutch Friesian horse population. Data consisted of 3,453 Dutch Friesian broodmares with 3,763 visual observations on IBH clinical symptoms scored by 12 inspectors during organized foal inspections in 2004 and 2008. Nine percent of the mares (n = 310) were scored in both years. Mares descended from 144 sires and 2,554 dams and 26.2% of the dams (n = 669) had more than 1 offspring in the data set (range: 2 to 6). Insect bite hypersensitivity was analyzed as a binary trait with a threshold animal model with and without a maternal effect, using a Bayesian approach. Observed IBH prevalence in Dutch Friesian broodmare population was 18.2%. Heritability on the liability scale was 0.16 (SD = 0.06); heritability on the observed scale was 0.07; and repeatability was 0.89 (SD = 0.03). Maternal effect was 0.17 (SD = 0.06) and significantly differed from zero, although the animal model without a maternal effect fitted the data better. These results show that genetic and permanent environmental factors affect IBH in Dutch Friesian horses. The dam affected the IBH development of her offspring through an additive genetic influence but also by being part of their rearing environment

Twelve Faculty of Homeopathy veterinarians recorded data systematically at 777 consecutive homeopathic appointments for horses over a period of 12 months. A spreadsheet enabled the recording of information, which included the date of appointment; horse and owner identity (anonymised); sex of horse; main medical problem treated; whether the condition was chronic or acute; whether the appointment was new or a follow-up; owner-assessed clinical outcome on a seven-point scale, ranging from -3 to +3, compared with the first appointment; homeopathic medicine(s) prescribed; and whether any conventional or other complementary/alternative medicine (CAM) was being used concurrently to treat the condition. Data from 289 horses comprised a total of 305 individual conditions identified as chronic in nature, of which 234 had a follow-up assessment. At the final appointment for chronic cases during the study period, 4.3 per cent were receiving conventional medication and 17.1 per cent were being given another CAM treatment in addition to homeopathy. The eight chronic conditions most frequently treated with homeopathy were: arthritis, headshaking, laminitis, chronic obstructive pulmonary disease, sweet itch, dermatitis, sarcoidosis and Cushing's syndrome.

Intradermal tests using a Culicoides nubeculosus extract have proven unreliable for diagnosis of equine insect bite hypersensitivity (IBH) in the Netherlands. The aim of this study was to evaluate the diagnostic value of an extract derived from the Dutch species C. obsoletus and C. pulicaris. Thirteen pairs of horses were tested, each pair consisting of one horse with IBH and the other a healthy control. Each horse was injected intradermally with 0.1 mL of three concentrations of Culicoides whole body extract (1 : 1000 w/v, 1 : 10,000 w/v and 1 : 25,000 w/v), histamine solution (0.01 mg/mL, positive control) and phosphate-buffered saline (negative control). Skin responses were evaluated after 30 min and at 1, 4 and 24 h. At all time points the absolute wheal diameter elicited by Culicoides extract 1 : 1000 w/v was significantly larger (P

Six horses severely affected by a seasonal dermatitis similar in both histopathology and epidemiology to Culicoides hypersensitivity (CH) and six unaffected or normal horses were inoculated intradermally with an extract of Culicoides obsoletus (Meigen), the most common Culicoides in southwestern British Columbia. Affected horses developed large welts within 20 min after injection, representing an immediate (type I) reaction; welts were largest 24 h or more after challenge, indicating in addition a delayed (type IV) reaction. This reaction was discernible for greater than 3 wk in some of the affected horses. Normal horses developed small welts which peaked 2-4 h after challenge. Affected horses were irritated by the injections and developed characteristically ridged skin at the injection sites, similar to that seen in natural lesions, whereas the normal horses showed neither discomfort nor clinical signs. C. obsoletus is one of the most numerous Culicoides species biting horses, feeds on parts of the body where lesions are found, and is, we believe, responsible for dermatitis in the Pacific Northwest. The skin test was repeated 2 yr later in three of the affected horses. In two, the reactions were similar to those in the first test, but in the third horse, the reaction was greatly reduced after the second test. This paralleled a decrease in the severity of its natural clinical signs. Thus, a skin test may be useful in the diagnosis of Culicoides hypersensitivity.

An Internet-based questionnaire among horse owners was carried out to identify factors affecting the incidence of insect bite hypersensitivity (IBHI) among horses in the Netherlands. Information was obtained for 794 horses of various breeds, but the breed distribution was not representative for the Dutch horse population. Of the horses for which information was available, 56% suffered from IBH and 44% did not. The most common clinical symptoms were pruritus, scaling, and hair loss, occurring mainly at the base of the tail and along the mane. Breed, age, region (and local habitat), stabling, type of bedding in the stable, use of the horse, deworming frequency, and season were associated with significant differences in IBH incidence. Knowledge of the factors influencing the incidence of IBH may make it possible to reduce the number of animals affected and help alleviate symptoms in affected horses. Om de factoren te identificeren die een rol spelen bij het voorkomen van staart- en-maneneczeem bij paarden in Nederland is een internet-enquête uitgevoerd. Informatie is verkregen van 794 paarden van verschillende rassen, hoewel de rasverdeling niet representatief was voor de Nederlandse paardenpopulatie

Summary Fourteen privately owned horses completed a six month, controlled, double-blind trial to assess the efficacy of immunotherapy using an aqueous extract of whole, unfed Culicoides variipennis in the treatment of Culicoides hypersensitivity. Selected horses had a history of a seasonal, pruritic dermatitis, clinical signs and distribution compatible with Culicoides hypersensitivity, failed to improve in response to ivermectin therapy, and reacted to several dilutions of Culicoides extracts without significant reactivity to other possible allergens including insects, moulds and feeds. One horse from the control group (n=8) and one from the test group (n=6) improved. Statistically, there was no significant difference between horses on Culicoides antigen and control horses. In each group, four owners thought that their horses had improved.

Reasons for performing study: It is expected that climate and habitat factors influence the prevalence of culicoides and, therefore, the prevalence of insect bite hypersensitivity (IBH), but very little is described in the literature to prove the association of these factors. Prevalence varies widely from 3% in certain areas of Great Britain to 60% in certain parts of Australia. Objectives: To describe the influence of environmental factors on the prevalence of IBH in Shetland ponies and Friesian horses in the Netherlands. Methods: Data on 3284 Shetland and 2824 Friesian mares (n = 6108) were collected in the Netherlands, based on 90 regions, according to postal codes. The climate components, amount of rainfall, number of warm days, number of cold days, and habitat components of soil type and type of vegetation were collected for each region. Results: Prevalence of IBH varied widely from 0-71.4% per region. The results showed that the environment with low IBH-prevalence had high rainfall, many cold days and few warm days per year. Habitats with a low IBH-prevalence were based along the coast line. Habitats with increasing prevalence of IBH had soils of clay with heather and woody vegetation. Friesian mares had a higher IBH prevalence than Shetland mares, which could indicate an effect of genetic background or an effect of year. Conclusions: There is an environmental effect on IBH prevalence within the Netherlands, which is caused by climate and habitat factors. Potential relevance: The results provide a more accurate description of environmental factors and their impact on development of IBH; and should help better to understand habitat and climate effects, and to distinguish these from other effects, such as animal factors (genetics, age or sex).

The effect of factors including the horses' farm environment, their sex and age and whether they suffered from summer seasonal recurrent dermatitis (sweet itch) on the concentrations of zinc in the plasma, whole blood and blood cells of 104 Icelandic horses was investigated. Its concentration in plasma varied significantly between farms (P0.01), but its concentration in blood and blood cells was not influenced by any of the variables. The concentration of zinc in the blood cells was 10.5 times greater than in plasma, but its concentration in plasma was not correlated with its concentration in whole blood or blood cells owing to the variability in the proportion of whole blood zinc present in plasma (relative plasma zinc), which ranged between 9 and 24 per cent. This variability was significantly influenced by a three-way interaction between farm, sex and sweet itch (P0.05). Relative plasma zinc was positively correlated with absolute plasma zinc (r=0.78, P0.001) and negatively correlated with whole blood and blood cellular zinc (r=-0.58, r=-0.71, P0.001).

Biting insects were sampled to investigate the cause(s) of dermatitis (putative Culicoides hypersensitivity [CHS]) on horses on the Palos Verdes Peninsula, Los Angeles County, California. Suction traps baited with CO2 were operated at 5 sites from April 2002 to August 2003, supplemented by sampling from horses. Six species of Culicoides, 7 species of mosquitoes, and occasional Simulium and Stomoxys were collected in traps. Culicoides sonorensis was the most common midge trapped, although C. obsoletus and C. freeborni also were collected repeatedly. Insects from the belly region of horses in spring (peak dermatitis period) were mostly C. obsoletus, which were far more abundant than indicated by CO2-baited suction traps. The predominant mosquito was Culiseta incidens; Culex quinquefasciatus and Cx. tarsalis also could be common, depending on the site. Mosquitoes, particularly Cs. incidens, were more abundant the 2nd year (normal rainfall), whereas C. sonorensis and C. freeborni were more abundant the 1st year (drought period). Culicoides obsoletus, supplemented by C. sonorensis, is regarded as a primary suspect causing CHS in this area.

Eosinophils have been implicated in the pathogenesis of the seasonal equine allergic skin disease, sweet itch. Protein kinase C (PKC) is involved in regulating eosinophil function and antigen challenge has been reported to alter PKC isotype expression in blood eosinophils from allergic human subjects. Here we have compared the pattern of PKC isotype expression in eosinophils from sweet itch ponies with that in cells from normal ponies both during the active and inactive phases of the disease. A role for PKC in histamine-induced eosinophil activation was also investigated. Conventional PKCs alpha and beta, novel PKCs delta and epsilon and atypical PKCs iota and zeta were identified in eosinophils pooled from four allergic ponies during the inactive phase, when no clinical signs were evident. The PKC isotypes, like those in eosinophils from normal ponies, were located primarily in the particulate fraction of the cell. Isotype expression in cells from normal and allergic animals did not appear to be different. In contrast, during the active phase of the disease, when the sweet itch ponies had clinical signs, the expression of PKCs beta, epsilon and iota in eosinophils from these animals appeared to be increased relative to that in cells from normal ponies. When PKC expression in eosinophils from five individual normal and sweet itch ponies was compared, small, but statistically significant, increases in PKC epsilon and PKCdelta expression were evident in eosinophils from the sweet itch ponies during the active and inactive phases, respectively. The non-selective PKC inhibitors, staurosporine and Ro31-8220, significantly reduced histamine-induced superoxide production. Use of Go6976, an inhibitor of conventional PKCs, suggested that PKCalpha and/or beta were involved and that there was significantly greater inhibition of the response in eosinophils obtained from sweet itch ponies during the active phase. There was no significant difference in histamine-induced superoxide production by eosinophils from allergic and normal ponies and the functional significance of the increased PKC isotype expression in eosinophils from sweet itch ponies relative to that in cells from healthy animals remains to be established.