Anne Couroucé

La grippe équine est l’une des principales maladies respiratoires infectieuses des équidés et demeure une cause majeure de pertes sanitaires et économiques pour la filière équine à travers le monde. Congrès de la disponibilité de vaccins, l’épizootie de 2025-2026 a rappelé que la circulation du virus reste favorisée par les mouvements d’équidés, une couverture vaccinale insuffisante et l’évolution continue des souches virales. Cet article propose une synthèse des connaissances actuelles sur le virus de la grippe équine, son évolution phylogénétique ainsi que les caractéristiques des souches H3N8 circulant actuellement en France et au niveau international. Les principaux vaccins disponibles en France, les protocoles vaccinaux des différents organismes de tutelle et les méthodes d’évaluation de la réponse immunitaire sont également présentés, avec un focus sur le test d’hémolyse radiale simple (SRH), méthode de référence recommandée par l’Organisation Mondiale de la Santé Animale. Enfin, l’épizootie de 2025-2026 est décrite, ainsi que les mesures de biosécurité permettant de prévenir l’introduction du virus et de limiter sa diffusion au sein des structures. Cette synthèse met en évidence le rôle central du vétérinaire praticien dans la prévention, la surveillance et la maîtrise de cette maladie respiratoire hautement contagieuse.

La rhinopneumonie équine forme nerveuse (myéloencéphalopathie à herpesvirus, MEH), causée par l’HVE-1, reste très redoutée depuis la crise de Valence en 2021. Ce virus très contagieux présente une latence et une séroprévalence supérieure à 60 %. La prévention repose d’abord sur la biosécurité : plan adapté à chaque structure, formation des intervenants, quarantaine des nouveaux arrivants, sécurisation des déplacements et des rassemblements, isolement immédiat de tout cheval suspect, diagnostic PCR sensible et gestion par lots. La vaccination protège à l’échelle individuelle et collective : elle réduit la charge virale, l’excrétion et les avortements. Aucun vaccin ne revendique d’effet sur la forme nerveuse de la maladie, faute de modèle d’étude adapté. Des informations circulent sur un lien entre la vaccination et le développement de la forme nerveuse, mais rien ne prouve qu’elle en soit à l’origine : ces études reposent sur des associations, non sur une causalité. Aucun antiviral n’a d’AMM contre la MEH et les résultats du valaciclovir sont discordants. Des travaux récents d’un consortium de laboratoires ont démontré l’efficacité in vitro du ganciclovir et de l’aménamévir. L’association de ces deux molécules montre un effet synergique sur différents modèles cellulaires équin. En conclusion, prévenir reste la meilleure stratégie : repérer et vite isoler le cas index, vacciner largement et ne pas relayer les fausses informations.

Ixodes ricinus is the main hard-tick vector of numerous pathogens across Europe, making its fine-scale distribution a key determinant of human and animal exposure risk. Existing habitat-suitability and distribution maps have already provided important knowledge on I. ricinus in France and Europe, including knowledge- based national mapping and European-scale species distribution models. Here, we present a complementary, occurrence-based machine-learning framework designed to produce an ecologically interpretable habitat- suitability map for mainland France, with predictor selection explicitly grounded in a PRISMA-guided synthesis of the literature. We systematically reviewed the European literature to identify climatic, environmental, and biological drivers of tick survival, development, and questing activity. These drivers were translated into spatial layers and filtered for collinearity, ecological relevance, and interpretability. Occurrence records from citizen- science and institutional sources were manually curated for taxonomic reliability and geographic precision. Pseudo-absences were generated using constrained strategies accounting for sampling bias and accessible-area geometry. Models were trained and evaluated using environmentally stratified cross-validation to limit spatial autocorrelation, and algorithms were benchmarked with optimized hyperparameters using discrimination metrics and ecological diagnostics. The resulting suitability maps revealed a strong national gradient primarily associated with land cover, saturation deficit, and intra-annual humidity variability. Suitability was highest in contiguous forested landscapes and lower in urbanized areas and regions characterized by high saturation deficit, including zones under Mediterranean climatic influence. The categorical map delineated coherent high- suitability cores separated by broad transition zones, consistent with known eco-physiological limits and habitat requirements of I. ricinus. Response curves highlighted sensitivity to desiccation-related variables and favourable conditions in forests and peri-urban wooded environments, supporting biological plausibility. Rather than aiming to replace existing maps, this framework contributes a transparent and reproducible data-driven approach for deriving a national relative suitability surface and critically evaluating inferred ecological relationships against published evidence. The resulting map should therefore be interpreted as an index of relative habitat suitability, not as a direct measure of tick abundance or infection risk. It may support targeted surveillance, guide field sampling strategies, and provide a spatial component for future integration with pathogen and host-distribution layers to derive relative exposure indices. The approach is transferable to other tick species or regions where heterogeneous occurrence data and literature-supported ecological predictors are available.

Background: Guttural pouch (GP) disorders are clinically important in horses, yet the relationship between endoscopic findings and GP cytology remains poorly defined. Hypothesis/Objectives: To establish reference cytological values for GP lavage fluid in horses and to investigate associations between inflammatory cytology and endoscopic findings. Animal: Asymptomatic racing horses sampled in the field and horses referred for investigation of respiratory disorders. Methods: Prospective cross-sectional study. Horses underwent clinical examination, upper airway endoscopy, and bilateral transendoscopic GP lavage. A GP inflammation score (0-15) was developed based on endoscopic appearance in the GP. Cytology was performed on GP pooled samples. Control horses were defined by the absence of clinical, hematologic, microbiological, and endoscopic abnormalities. Associations were analyzed using nonparametric tests. Results: A total of 173 horses were included, of which 19 were controls. Control GP fluid cytology exhibited no or rare cells (median 30 cells/mm3; range 10-90) which were either neutrophils, macrophages, or lymphocytes. The remaining 154 horses were classified as “abnormal” (ABN) and subdivided into 2 groups according to GP fluid neutrophil proportions: group ABN1 (<1% neutrophils, n = 101, median 30 cells/mm3; range 5-360) and group ABN2 (neutrophils ≥ 1%, n = 53, median 100 cells/mm3; range 30-600). Horses in the ABN2 group showed more frequent GP lymphoid hyperplasia, secretions, and purulent exudate than horses in ABN1. Conclusions and clinical importance: Cytological inflammation correlates with endoscopic evidence of GP inflammation.

Background: Public scrutiny of racehorse welfare is increasing. The preparatory training phase preceding the racing season is potentially a critical period for physical and mental development. Structured welfare assessment protocols have recently been developed, but their use in field conditions remains limited. Objectives: (1) To evaluate the field applicability of a racehorse‐specific welfare assessment protocol in a professional French jump racing yard; and (2) to explore whether it can detect relevant physical and behavioural changes in young horses during season preparation. Study Design: Longitudinal observational study with repeated measures. Methods: Sixteen two‐ to three‐year‐old racehorses (10 Thoroughbreds, 6 French Non‐Thoroughbreds) from a single jump racing yard were assessed at three time points (T0, T1, T2) over 5 months before the racing season. Direct observations included environmental conditions, physical health, horse grimace scale (HGS), human–horse relationship tests, and behavioural activity budgets via scan sampling. Mixed‐effects models evaluated temporal changes and associated factors. Results: Horses were healthy, with adequate nutrition and comfort, though no free turn‐out and social contact often limited to visual interaction (68%). Body condition score decreased significantly at T1 (β = −0.96; 95% CI: [−1.7, −0.26]; p = 0.007) and T2 (β = −2.0; 95% CI: [−2.9, −1.1]; p < 0.001). Lip commissure lesions were prevalent (external 65%, internal 75%). HGS scores increased significantly at T2 (β = 1.7; 95% CI: [0.85, 2.6]; p < 0.001), and horses with physical social contact had lower scores (β = −1.3; 95% CI: [−2.3, −0.22]; p = 0.02). Behavioural activity budgets showed inter‐individual variability. Main Limitations: Small sample size and attrition limit generalisability. Assessments were conducted during routine training days without altering management, occasionally limiting evaluations. Conclusions: Structured welfare assessments are feasible in field conditions, highlight areas for improvement, and can capture relevant changes during jump racing season preparation.

Background: Fungi are ubiquitous in horses' environment. Their contribution to the pathophysiology of severe asthma (SA) is acknowledged, while controversies remain for mild–moderate asthma (MA).Objectives: We hypothesised that fungi are a risk factor for asthma. Our objective was to compare different combinations of analytical methods (cytology, culture) and sampling sites (tracheal wash (TW), bronchoalveolar lavage fluid (BALF)) in relation to clinical status (control, MA, SA).Study design: Prospective cross‐sectional study.Methods: The study population included asymptomatic racing horses in the field and horses referred to the hospital for respiratory investigations. Fungi were detected by cytology and identified by mycology on TW and pooled BALF. Chi‐square tests and multivariable logistic regressions were used for prevalence comparison between groups and association with clinical investigations.Results: In total 155 horses (85 MA, 35 SA and 35 controls) were included in the study. The overall proportions of fungal detection in TW ranged from 45.7% to 89.4% among groups. The prevalence of fungal detection in BALF was significantly lower by cytology for SA (5.7%) than MA horses (23.6%) and significantly higher by culture for MA horses (31.8%) than controls (8.6%). Fungal detection by culture in BALF was significantly associated with high tracheal mucus score, high neutrophil proportions in BALF and diagnosis of MA.Main limitations: Mycology was only performed in pooled BALF, and environment was not sampled.Conclusions: Fungi were significantly more prevalent in the airways of MA horses than SA and/or controls. Fungal detection on TW, either by cytology or culture, was uninformative in a clinical context. Fungal detection by culture, but not cytology in BALF was associated with MA.

A state-of-the-art multi-omics approach was applied to improve our understanding of the aetio-pathogenesis of a highly prevalent, performance-limiting disorder of racehorses: mild-to-moderate equine asthma (MMEA). This is a prerequisite to improving prophylactic, management, and therapeutic options for this condition. Although a number of risk factors have been identified, options for intervention are limited. This study applied a multi-omic approach to reveal key inflammatory pathways involved in inflammatory cell recruitment to the lower airways and highlight distinct MMEA inflammatory profiles. We compared bronchoalveolar lavage fluid (BALF) cell gene and protein expression data from horses with non-inflammatory BALF cytology with those isolated from horses with neutrophilic, mastocytic, mixed neutrophilic/mastocytic, and eosinophilic/mastocytic inflammation. The analyses on transcriptomic/proteomic data derived from BALF from horses with neutrophilic cytology showed enrichment in classical inflammatory pathways, and horses with mastocytic inflammation showed enrichment in pathways involved in hypersensitivity reactions related to nonclassical inflammation potentially mimicking a Th2-immune response. The mixed eosinophilic/mastocytic group also presented with a nonclassical inflammatory profile, whereas the mixed neutrophilic/mastocytic group revealed profiles consistent with both neutrophilic inflammation and hypersensitivity. Our adopted multi-omics approach provided a holistic assessment of the immunological status of the lower airways associated with the different cytological profiles of equine asthma.

Background: Fungi are ubiquitous in horses’ environment. Their contribution to the pathophysiology of severe asthma (SA) is acknowledged, while controversies remain for mild-moderate asthma (MA). Objectives: We hypothesized that fungi were a risk factor for asthma. Our objective was to compare different combinations of analytical methods (cytology, culture) and sampling sites (tracheal wash (TW), bronchoalveolar lavage fluid (BALF)) in relation to clinical status (control, MA, SA). Study design: Prospective cross-sectional study. Methods: The study population included asymptomatic racing horses in the field and horses referred to the hospital for respiratory investigations. Fungi were detected by cytology and identified by mycology on TW and pooled BALF. Chi-square tests were used for prevalence comparison between groups and association with clinical investigations. Results: A total of 155 horses (85 MA, 35 SA and 35 controls) were included in the study. The overall proportions of fungal detection in TW ranged from 45.7% to 89.4% among groups. The prevalence of fungal detection in BALF was significantly lower by cytology for SA (5.7%) than MA horses (23.6%) and significantly higher by culture for MA horses (31.8%) than controls (8.6%). Fungal detection by culture in BALF was significantly associated with high tracheal mucus score, high neutrophil proportions in BALF and diagnosis of MA. Main limitations: Mycology was only performed in pooled BALF, and environment was not sampled. Conclusion and clinical importance: Fungi were significantly more prevalent in the airways of MA horses than SA and/or controls. Fungal detection on TW, either by cytology or culture, was uninformative in a clinical context. Fungal detection by culture (but not cytology) in BALF represents a risk factor for MA.

The aim of this study is to describe clinical data associated with acorn intoxication and to find variables associated with survival. Data from horses presented at CISCO-ONIRIS from 2011 to 2018 with a diagnosis of acorn intoxication were included. Diagnosis was based on the following: season, the presence of acorns in the environment, clinical and hemato-biochemical parameters suggestive of a digestive/renal disease, the co-morbidity of companion animals, and post-mortem findings. Statistical analysis was completed using Student’s t-test for mean comparisons and a Chi-square test for group comparisons (p < 0.05). A total of 25 horses were included, and seasonality suggests that the intoxication may vary from year to year. Clinical signs associated with acorn intoxication were signs of circulatory shock (lethargy, tachycardia, abnormal mucous membrane, tachypnea), digestive signs (diarrhea, ileus, colic), and abnormal temperature. Clinical pathological findings included increased hematocrit, WBC, creatinine, BUN, GGT, AST, CK and decreased albumin. Overall, 44% (11/25) of horses survived. The majority (13/14) of non-survivors died, or were euthanized, during the first 48 h. Findings significantly associated with non-survival were age, heart rate, hemorrhagic diarrhea, ileus, hematocrit, creatinine, blood lactate, and thickness of the colon wall at ultrasonography. This study provides equine practitioners with valuable prognostic information in cases of acorn intoxication.