Bronchial brush cytology, endobronchial biopsy, and SALSA immunohistochemistry in severe equine asthma.

Horses with severe equine asthma (SEA), also known as heaves and recurrent airway obstruction, have persistent neutrophilic inflammation of the lower airways. Cytologic evaluation of bronchoalveolar lavage (BAL) fluid is commonly used to confirm the clinical diagnosis of SEA. However, the utility of microscopic assessment of bronchial brushings, endobronchial biopsies, and immunohistochemical detection of disease-associated biomarkers for the diagnosis of SEA remain poorly characterized. Salivary scavenger and agglutinin (SALSA) has anti-inflammatory properties and downregulated gene expression in SEA; therefore, it was investigated as a tissue biomarker for airway and systemic inflammation. Six asthmatic and 6 non-asthmatic horses were exposed to an inhaled challenge. Before and after challenge, samples of BAL fluid, bronchial brushing, and endobronchial biopsy were collected. Location of SALSA in biopsies was determined, and immunohistochemical label intensity was computed using image analysis software. Serum amyloid A (SAA) was measured to assess systemic inflammation. After challenge, neutrophil proportions were significantly higher in asthmatic versus non-asthmatic horses in BAL fluid (least squares means, 95% confidence interval: 80.9%, 57.2% to 93.1%, vs 3.6%, 1.1% to 10.7%) and in brush cytology slides (39.5%, 7.7% to 83.6%, vs 0.2%, 0% to 2.3%), illustrating the potential of brush cytology as an alternate modality to BAL for assessing intraluminal inflammation. Bronchial histopathologic findings and intensity of SALSA immunolabeling in surface and glandular epithelium were similar in asthmatic and non-asthmatic horses, indicating limited changes in bronchial tissue from the inhaled challenge. Increases in SAA indicated systemic inflammation, but SALSA immunolabeling did not change significantly.

Flow cytometric analysis of equine bronchoalveolar lavage fluid cells in horses with and without severe equine asthma.

Severe equine asthma (SEA) is a common, debilitating lower airway inflammatory disorder of older horses. Alveolar macrophages (AMs) survey inhaled particulates from barn sources causing them to switch from an anti-inflammatory to a proinflammatory phenotype, resulting in neutrophil recruitment to the lung. This proinflammatory switch may contribute to the development and prolongation of SEA. Validated antibodies to identify the cells involved in the pathogenesis of SEA are lacking. In this study, monoclonal antibodies against CD90, CD163, and CD206 were tested for reactivity with equine leukocytes by immunocytochemistry and flow cytometry. A multi-color flow cytometric assay was developed to identify leukocytes in equine bronchoalveolar lavage fluid (BALF). Four control and 4 SEA-susceptible horses had BALF collected before and after a 48-hour moldy hay challenge. Antibodies against CD90 uniquely labeled equine neutrophils, and antibodies against CD163 and CD206 identified equine macrophages. Postchallenge AM surface expression of CD163 increased in both groups of horses, but the increase was statistically significant in only the SEA-susceptible group (P = .02). The surface expression of CD206 on AMs increased significantly in the SEA-susceptible group (P = .03) but was unchanged in the control group (P = .5). Increased expression of CD163 and CD206 during exacerbation of SEA suggested an association between AM phenotype and lung inflammation. However, functions of AMs in the pathogenesis of SEA remain to be elucidated.

Spontaneous resolution of bilateral congenital patellar luxation in an alpaca cria.

An 8-day-old alpaca was presented for suspected meconium impaction and abnormal gait and posture. Physical examination revealed bilateral medial patellar luxation. In previous reports, medical treatment of patellar luxation in crias has been associated with a poor to grave prognosis; here we report a case of successful resolution.

Résolution spontanée d'une luxation patellaire bilatérale congénitale chez un bébé alpaga. Un alpaga âgé de 8 jours a été présenté pour une impaction soupçonnée du méconium et une démarche et une posture anormales. L'examen physique a révélé une luxation patellaire médiale bilatérale. Dans des rapports antérieurs, le traitement médical de la luxation patellaire chez les bébés alpaga a été associé à un pronostic sombre ou grave; nous avons ici un rapport de cas d'une résolution réussie.(Traduit par Isabelle Vallières).

Impaired response of the bronchial epithelium to inflammation characterizes severe equine asthma.

BACKGROUND: Severe equine asthma is a naturally occurring lung inflammatory disease of mature animals characterized by neutrophilic inflammation, bronchoconstriction, mucus hypersecretion and airway remodeling. Exacerbations are triggered by inhalation of dust and microbial components. Affected animals eventually are unable of aerobic performance. In this study transcriptomic differences between asthmatic and non-asthmatic animals in the response of the bronchial epithelium to an inhaled challenge were determined. RESULTS: Paired endobronchial biopsies were obtained pre- and post-challenge from asthmatic and non-asthmatic animals. The transcriptome, determined by RNA-seq and analyzed with edgeR, contained 111 genes differentially expressed (DE) after challenge between horses with and without asthma, and 81 of these were upregulated. Genes involved in neutrophil migration and activation were in central location in interaction networks, and related gene ontology terms were significantly overrepresented. Relative abundance of specific gene products as determined by immunohistochemistry was correlated with differential gene expression. Gene sets involved in neutrophil chemotaxis, immune and inflammatory response, secretion, blood coagulation and apoptosis were overrepresented among up-regulated genes, while the rhythmic process gene set was overrepresented among down-regulated genes. MMP1, IL8, TLR4 and MMP9 appeared to be the most important proteins in connecting the STRING protein network of DE genes. CONCLUSIONS: Several differentially expressed genes and networks in horses with asthma also contribute to human asthma, highlighting similarities between severe human adult and equine asthma. Neutrophil activation by the bronchial epithelium is suggested as the trigger of the inflammatory cascade in equine asthma, followed by epithelial injury and impaired repair and differentiation. Circadian rhythm dysregulation and the sonic Hedgehog pathway were identified as potential novel contributory factors in equine asthma.

Ultrasonography detects early laryngeal muscle atrophy in an equine neurectomy model.

INTRODUCTION: A unilateral neurectomy model was used to study the relationship between histologic and ultrasonographic tissue characteristics during muscle atrophy over time. METHODS: This investigation was an in vivo experimental study in an equine model (n = 28). Mean pixel intensity of ultrasonographic images was measured, a muscle appearance grade was assigned weekly, and muscles were harvested from 4 to 32 weeks. Minimum fiber diameter, fiber density per unit area, percent collagen, percent fat, and fiber type profile were measured from muscle cryosections and correlated with the ultrasonographic parameters. RESULTS: A significant relationship was identified between collagen content, minimum fiber diameter, and ultrasonographic muscle appearance by as early as 8 weeks. There was no apparent association between fat content of muscle and the ultrasonographic appearance of atrophy before 28 weeks. CONCLUSIONS: Early muscle atrophy before fatty infiltration is detectable with ultrasound. The effect of muscle collagen content on echointensity may be mediated by reduced fiber diameter.

Acetazolamide attenuates transvascular fluid flux in equine lungs during intense exercise.

During intense exercise in horses the transvascular fluid flux in the pulmonary circulation (Jv-a) represents 4% of cardiac output (Q). This fluid flux has been attributed to an increase in pulmonary transmural hydrostatic forces, increases in perfused microvascular surface area, and reversible alterations in capillary permeability under conditions of high flow and pressure. Erythrocyte fluid efflux, however, accounts for a significant fraction of Jv-a. In the lung the Jacobs-Stewart cycle occurs with diffusion of CO2 into alveolar space with possible accompanying chloride (Cl-) and water movement from the erythrocyte directly into the pulmonary interstitium. We hypothesised that inhibition of carbonic anhydrase in erythrocytes inhibits the Jacobs-Stewart cycle and attenuates Jv-a. Five horses were exercised on a treadmill until fatigue without (control) and with acetazolamide treatment (30 mg kg(-1) 30 min before exercise). Erythrocyte fluid efflux, plasma fluid flux across the lung and Jv-a were calculated using haemoglobin, haematocrit, plasma protein and Q. Fluid fluxes were used to calculate erythrocyte, plasma and whole blood Cl- fluxes across the lung. Cardiac output was not different between control and acetazolamide treatment. During exercise erythrocyte fluid efflux and Jv-a increased in control (9.3±3.3 and 11.0±4.4 l min(-1), respectively) and was higher than after acetazolamide treatment (3.8±1.6 and 1.2±1.2 l min(-1), respectively) (P<0.05). Plasma fluid flux did not change from rest in control and decreased after acetazolamide treatment (-4.5±1.5 l min(-1)) (P<0.05). Erythrocyte Cl- flux increased during exercise in control and after acetazolamide treatment (P<0.05). During exercise plasma Cl- flux across the lung did not change in control; however, it increased with acetazolamide treatment (P=0.0001). During exercise whole blood Cl- flux increased across the lung in control (P<0.05) but not after acetazolamide treatment. The results indicate that Jv-a in the lung is dependent on the Jacobs-Stewart cycle and mostly independent of transmural hydrostatic forces. It also appears that Jv-a is mediated by Cl- and water egress from erythrocytes directly into the interstitium without transit through plasma.

Phylogenetic relationships among Perissodactyla: secretoglobin 1A1 gene duplication and triplication in the Equidae family.

Secretoglobin family 1A member 1 (SCGB 1A1) is a small anti-inflammatory and immunomodulatory protein that is abundantly secreted in airway surface fluids. We recently reported the existence of three distinct SCGB1A1 genes in the domestic horse genome as opposed to the single gene copy consensus present in other mammals. The origin of SCGB1A1 gene triplication and the evolutionary relationship of the three genes amongst Equidae family members are unknown. For this study, SCGB1A1 genomic data were collected from various Equus individuals including E. caballus, E. przewalskii, E. asinus, E. grevyi, and E. quagga. Three SCGB1A1 genes in E. przewalskii, two SCGB1A1 genes in E. asinus, and a single SCGB1A1 gene in E. grevyi and E. quagga were identified. Sequence analysis revealed that the non-synonymous nucleotide substitutions between the different equid genes coded for 17 amino acid changes. Most of these changes localized to the SCGB 1A1 central cavity that binds hydrophobic ligands, suggesting that this area of SCGB 1A1 evolved to accommodate diverse molecular interactions. Three-dimensional modeling of the proteins revealed that the size of the SCGB 1A1 central cavity is larger than that of SCGB 1A1A. Altogether, these findings suggest that evolution of the SCGB1A1 gene may parallel the separation of caballine and non-caballine species amongst Equidae, and may indicate an expansion of function for SCGB1A1 gene products.

Genomic analysis of a Canadian equine rhinitis A virus reveals low diversity among field isolates.

Equine rhinitis A virus (ERAV) is an ubiquitous virus, routinely identified in equine respiratory infections; however, its role in disease and genetic features are not well defined due to a lack of genomic characterization of the recovered isolates. Therefore, we sequenced the full-length genome of a Canadian ERAV (ERAV/ON/05) and compared it with other ERAV sequences currently available in GenBank. The ERAV/ON/05 genome is 7,839 nucleotides (nts) in length with a variable 5'UTR and a more conserved 3'UTR. When ERAV/ON/05 was compared to other reported ERAV isolates, an insertion of 13 nt in the 5'UTR was identified. Further phylogenetic analysis demonstrated that ERAV/ON/05 is closely related to the ERAV/PERV isolate, which was isolated in 1962 in the United Kingdom. The polyprotein of ERAV/ON/05 had a 96 % nucleotide and amino acid sequence identity to reported ERAVs, and it appears that, despite the high error rate of RNA-dependent RNA polymerase, this isolate has retained high sequence identity to the strain first described by Plummer in 1962.

Multiple secretoglobin 1A1 genes are differentially expressed in horses.

BACKGROUND: Secretoglobin 1A1 (SCGB 1A1), also called Clara cell secretory protein, is the most abundantly secreted protein of the airway. The SCGB1A1 gene has been characterized in mammals as a single copy in the genome. However, analysis of the equine genome suggested that horses might have multiple SCGB1A1 gene copies. Non-ciliated lung epithelial cells produce SCGB 1A1 during inhalation of noxious substances to counter airway inflammation. Airway fluid and lung tissue of horses with recurrent airway obstruction (RAO), a chronic inflammatory lung disease affecting mature horses similar to environmentally induced asthma of humans, have reduced total SCGB 1A1 concentration. Herein, we investigated whether horses have distinct expressed SCGB1A1 genes; whether the transcripts are differentially expressed in tissues and in inflammatory lung disease; and whether there is cell specific protein expression in tissues. RESULTS: We identified three SCGB1A1 gene copies on equine chromosome 12, contained within a 512-kilobase region. Bioinformatic analysis showed that SCGB1A1 genes differ from each other by 8 to 10 nucleotides, and that they code for different proteins. Transcripts were detected for SCGB1A1 and SCGB1A1A, but not for SCGB1A1P. The SCGB1A1P gene had most inter-individual variability and contained a non-sense mutation in many animals, suggesting that SCGB1A1P has evolved into a pseudogene. Analysis of SCGB1A1 and SCGB1A1A sequences by endpoint-limiting dilution PCR identified a consistent difference affecting 3 bp within exon 2, which served as a gene-specific "signature". Assessment of gene- and organ-specific expression by semiquantitative RT-PCR of 33 tissues showed strong expression of SCGB1A1 and SCGB1A1A in lung, uterus, Fallopian tube and mammary gland, which correlated with detection of SCGB 1A1 protein by immunohistochemistry. Significantly altered expression of the ratio of SCGB1A1A to SCGB1A1 was detected in RAO-affected animals compared to controls, suggesting different roles for SCGB 1A1 and SCGB 1A1A in this inflammatory condition. CONCLUSIONS: This is the first report of three SCGB1A1 genes in a mammal. The two expressed genes code for proteins predicted to differ in function. Alterations in the gene expression ratio in RAO suggest cell and tissue specific regulation and functions. These findings may be important for understanding of lung and reproductive conditions.

Effect of intrabronchial administration of autologous adipose-derived mesenchymal stem cells on severe equine asthma.

BACKGROUND: Severe equine asthma (SEA) is a common chronic respiratory disease and a significant health and well-being problem in horses. Current therapeutic strategies improve pulmonary function and clinical signs in some horses, but in the long-term, return to full athletic function appears to be rare. The aim of this study was to assess the safety and the effect of intrabronchial administration of adipose-derived mesenchymal stem cells (AD-MSC) on pulmonary inflammatory and clinical parameters in horses with SEA. METHODS: This was a randomized controlled trial. Twenty adult horses diagnosed with SEA were randomly divided into two groups (n = 10), and treated either with a single intrabronchial application of autologous AD-MSC or oral dexamethasone for three weeks. A targeted clinical examination with determination of clinical score, maximal change in pleural pressure during the breathing cycle, and an endoscopic examination of the airways were performed at baseline and three weeks after treatment. Bronchoalveolar lavage fluid was analyzed cytologically, and IL-1ß, IL-4, IL-8, IL-17, TNFα and IFNγ mRNA and protein concentrations were measured at baseline and three weeks. The horses were then monitored over one year for recurrence of SEA. A non-inferiority analysis and a linear mixed-effects model were performed to assess differences between treatments. RESULTS: The non-inferiority of AD-MSC treatment was not established. However, AD-MSC administration significantly ameliorated the clinical score (P = 0.01), decreased the expression of IL-17 mRNA (P = 0.05) and IL-1ß (P ≤ 0.001), IL-4 (P ≤ 0.001), TNFα (P = 0.02) protein levels, and had a positive long-term effect on SEA-associated clinical signs (P = 0.02). CONCLUSIONS: Intrabronchial administration of AD-MSC had limited short-term anti-inflammatory effects but improved the clinical signs of SEA at one year.

Cardiopulmonary effects and recovery characteristics associated with 2 sedative protocols for assisted ventilation in healthy neonatal foals.

Neonatal foals may require prolonged sedation to permit ventilatory support in the first few days of life. The objective of this study was to evaluate and compare the cardiopulmonary effects and clinical recovery characteristics of 2 sedative/analgesia protocols in healthy foals receiving assisted ventilation. Foals were randomized to receive dexmedetomidine, butorphanol, and propofol (DBP) or midazolam, butorphanol, and propofol (MBP) during a 24-hour period. Infusion rates of dexmedetomidine, midazolam, and propofol were adjusted and propofol boluses administered according to set protocols to maintain optimal sedation and muscle relaxation. Ventilatory support variables were adjusted to preset targets. Physiologic variables were recorded, cardiac output (CO) measured (thermodilution), and arterial and mixed venous blood collected for gas analysis at intervals up to 24 hours. Foals in group DBP received dexmedetomidine [2.4 ± 0.5 µg/kg body weight (BW) per hour], butorphanol (13 µg/kg BW per hour), and propofol (6.97 ± 0.86 mg/kg BW per hour), whereas foals in group MBP received midazolam (0.14 ± 0.04 mg/kg BW per hour), butorphanol (13 µg/kg BW per hour), and propofol (5.98 ± 1.33 mg/kg BW per hour). Foals in the DBP group received significantly more propofol boluses (9.0 ± 3.0) than those in the MBP group (4.0 ± 2.0). Although physiologic variables remained within acceptable limits, heart rate (HR), mean arterial pressure (MAP), and cardiac index (CI) were lower in foals in the DBP group than in the MBP group. Times to sternal recumbency, standing, and nursing were significantly shorter in the DBP than MBP group. We found that MBP and DBP protocols are suitable to assist ventilatory support in neonatal foals, although MBP results in a prolonged recovery compared to DBP.

Les poulains nouveau-nés peuvent nécessiter une sédation prolongée pour permettre une assistance ventilatoire au cours des premiers jours de vie. L'objectif de cette étude était d'évaluer et de comparer les effets cardio-pulmonaires et les caractéristiques de récupération clinique de deux protocoles sédatifs/analgésiques chez des poulains sains recevant une ventilation assistée. Les poulains ont été randomisés pour recevoir de la dexmédétomidine, du butorphanol et du propofol (DBP) ou du midazolam, du butorphanol et du propofol (MBP) pendant une période de 24 heures. Les débits de perfusion de dexmédétomidine, de midazolam et de propofol ont été ajustés et des bolus de propofol ont été administrés selon des protocoles définis pour maintenir une sédation et une relaxation musculaire optimales. Les variables d'assistance ventilatoire ont été ajustées à des cibles prédéfinies. Les variables physiologiques ont été enregistrées, le débit cardiaque (CO) mesuré (thermodilution) et le sang artériel et veineux mixte prélevé pour analyse des gaz à des intervalles allant jusqu'à 24 h. Les poulains du groupe DBP ont reçu de la dexmédétomidine [2,4 ± 0,5 µg/kg de poids corporel (PC) par heure], du butorphanol (13 µg/kg de PC par heure) et du propofol (6,97 ± 0,86 mg/kg de PC par heure), tandis que les poulains du groupe MBP ont reçu du midazolam (0,14 ± 0,04 mg/kg de PC par heure), du butorphanol (13 µg/kg de PC par heure) et du propofol (5,98 ± 1,33 mg/kg de PC par heure). Les poulains du groupe DBP ont reçu significativement plus de bolus de propofol (9,0 ± 3,0) que ceux du groupe MBP (4,0 ± 2,0). Bien que les variables physiologiques soient restées dans des limites acceptables, la fréquence cardiaque (FC), la pression artérielle moyenne (MAP) et l'index cardiaque (IC) étaient plus faibles chez les poulains du groupe DBP que dans le groupe MBP. Les temps de décubitus sternal, de station debout et d'allaitement étaient significativement plus courts dans le groupe DBP que dans le groupe MBP. Nous avons constaté que les protocoles MBP et DBP sont adaptés pour assister l'assistance ventilatoire chez les poulains nouveau-nés, bien que le MBP entraîne une récupération prolongée par rapport au DBP.(Traduit par Docteur Serge Messier).

Experimental induction of recurrent airway obstruction with inhaled fungal spores, lipopolysaccharide, and silica microspheres in horses.

OBJECTIVE: To evaluate experimental induction of recurrent airway obstruction (RAO) with inhaled fungal spores, lipopolysaccharide, and silica microspheres in horses. ANIMALS: 7 horses with and 3 horses without a history of RAO. PROCEDURES: RAO-susceptible horses ranged in age from 17 to approximately 30 years, and control horses ranged in age from 7 to approximately 15 years. Pure mold cultures were derived from repeated culture of hay and identified via gene amplification and sequencing. Pulmonary function testing and bronchoalveolar lavage were performed before and after nebulization with a suspension of spores derived from 3 fungi, lipopolysaccharide, and 1-microm silica microspheres in all horses. This was followed by a 4-month washout period and a further pulmonary function test followed by saline (0.9% NaCl) solution challenge and bronchoalveolar lavage. RESULTS: Lichtheimia corymbifera, Aspergillus fumigatus, and Eurotium amstelodami were consistently identified in cultures of moldy hay. Nebulization with fungal spores, lipopolysaccharide, and microspheres induced significant increases in pleural pressure in RAO-susceptible but not control horses. Airway neutrophilia developed in both groups of horses with exposure to challenge material but more severely in RAO-susceptible horses. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that inhalation of fungal spores in combination with lipopolysaccharide and silica microspheres can induce disease exacerbation in susceptible horses and may thus be a useful model for future standardized studies of RAO in horses.

Suspected transient pseudohypoaldosteronism in a 10-day-old quarter horse foal.

A 10-day-old quarter horse colt was presented for signs of disorientation and inability to nurse. Hydronephrosis/hydroureters, with concomitant pyelonephritis and a severe electrolytes disturbance, were diagnosed. The clinical findings closely resembled those described for a syndrome of transient pseudohypoaldosteronism in human neonates.

Histologic investigation of airway inflammation in postmortem lung samples from racehorses.

OBJECTIVE To describe histologic findings in the small airways during postmortem examination of actively racing horses and to quantify the degree of airway inflammation by use of a semiquantitative scoring system. SAMPLE Lung tissues obtained from 95 horses (Thoroughbreds, Standardbreds, and Quarter Horses) that had been actively racing or training. PROCEDURES 10 standardized lung sections were obtained during postmortem examination of 37 horses that had been actively racing or training, and 2 histologic sections of the caudodorsal lung lobes previously collected from each of 58 horses that died or were euthanized during racing or training were also obtained. Sections were evaluated by use of a validated histologic small airway scoring system. RESULTS Scores for inflammatory cells, smooth muscle, and hemosiderin typically were high. Signalment and cause of death were not significant predictors of lung scores. Lung sample location was a significant predictor, with the highest scores in the caudal and dorsal sections. Inflammatory cell infiltration in peribronchiolar tissues, smooth muscle hyperplasia, and hemosiderin (prevalence of 86%, 98%, and 80%, respectively) were common findings in lungs of these horses, with the caudodorsal regions more severely affected. Correlation was moderate between smooth muscle hyperplasia and inflammatory cell infltration, with minimal correlation between hemosiderin and inflammatory cell infiltration. CONCLUSIONS AND CLINICAL RELEVANCE Inflammatory airway disease has been identified by use of bronchoalveolar lavage in young athletic horses throughout the world. In the study reported here, pathological changes were detected in the wall of small airways of horses that were actively training or racing.

Gene set enrichment analysis of the bronchial epithelium implicates contribution of cell cycle and tissue repair processes in equine asthma.

Severe equine asthma is a chronic inflammatory condition of the lower airways similar to adult-onset asthma in humans. Exacerbations are characterized by bronchial and bronchiolar neutrophilic inflammation, mucus hypersecretion and airway constriction. In this study we analyzed the gene expression response of the bronchial epithelium within groups of asthmatic and non-asthmatic animals following exposure to a dusty hay challenge. After challenge we identified 2341 and 120 differentially expressed genes in asthmatic and non-asthmatic horses, respectively. Gene set enrichment analysis of changes in gene expression after challenge identified 587 and 171 significantly enriched gene sets in asthmatic and non-asthmatic horses, respectively. Gene sets in asthmatic animals pertained, but were not limited, to cell cycle, neutrophil migration and chemotaxis, wound healing, hemostasis, coagulation, regulation of body fluid levels, and the hedgehog pathway. Furthermore, transcription factor target enrichment analysis in the asthmatic group showed that transcription factor motifs with the highest enrichment scores for up-regulated genes belonged to the E2F transcription factor family. It is postulated that engagement of hedgehog and E2F pathways in asthmatic horses promotes dysregulated cell proliferation and abnormal epithelial repair. These fundamental lesions may prevent re-establishment of homeostasis and perpetuate inflammation.

Inflammatory airway disease of horses.

The purpose of this consensus statement is to provide a review of current knowledge and opinions concerning inflammatory airway disease (IAD) and to help practitioners differentiate IAD from heaves (or recurrent airway obstruction; RAO) and other inflammatory respiratory diseases of horses.

Implementation of an algorithm for selection of antimicrobial therapy for diarrhoeic calves: Impact on antimicrobial treatment rates, health and faecal microbiota.

This study evaluated the impact of an algorithm targeting antimicrobial therapy of diarrhoeic calves on the incidence of diarrhoea, antimicrobial treatment rates, overall mortality, mortality of diarrhoeic calves and changes in the faecal microbiota. The algorithm was designed to target antimicrobial therapy in systemically ill calves from on two dairy farms. Retrospective (farm 1: 529 calves; farm 2: 639 calves) and prospective (farm 1: 639 calves; farm 2: 842 calves) cohorts were examined for 12 months before and after implementation of the algorithm. The Mantel-Haenszel test and Kaplan-Meier survival curves were used to assess the cumulative incidence risk (CIR) and time to development of each outcome before and after implementation of the algorithm. The CIR of antimicrobial treatment rates was 80% lower after implementation of the algorithm on both farms (CIR 0.19, 95% confidence interval 0.17-0.21). There was no difference in the CIR of overall mortality, but the CRI for mortality of diarrhoeic calves was lower in the period after implementation of the algorithm on one farm. The faecal microbiota of 15 healthy calves from both farms at each time period were characterised using a sequencing platform targeting the V4 region of the 16S rRNA gene. On both farms, there were significant differences in community membership and structure (parsimony P<0.001). Use of the algorithm for treatment of diarrhoeic calves reduced antimicrobial treatment rates without a negative impact on the health of calves. However, the experimental design did not take into account the potential confounding effects of dietary changes between the study periods.

Development of a technique for determination of pulmonary artery pulse wave velocity in horses.

Calcification of the tunica media of the axial pulmonary arteries (PA) has been reported in a large proportion of racehorses. In humans, medial calcification is a significant cause of arterial stiffening and is implicated in the pathogenesis of cardiac, cerebral, and renal microvascular diseases. Pulse wave velocity (PWV) provides a measure of arterial stiffness. This study aimed to develop a technique to determine PA-PWV in horses and, secondarily, to investigate a potential association between PA-PWV and arterial fibro-calcification. A dual-pressure sensor catheter (PSC) was placed in the main PA of 10 sedated horses. The pressure waves were used to determine PWV along the PA, using the statistical phase offset method. Histological analysis of the PA was performed to investigate the presence of fibro-calcified lesions. The mean (±SD) PWV was 2.3 ± 0.7 m/s in the proximal PA trunk and 1.1 ± 0.1 m/s further distal (15 cm) in a main PA branch. The mean (±SD) of mean arterial pressures in the proximal PA trunk was 30.1 ± 5.2 mmHg, and 22.0 ± 6.0 mmHg further distal (15 cm) within the main PA branch. The mean (±SD) pulse pressure in the proximal PA trunk was 15.0 ± 4.7 mmHg, and 13.5 ± 3.3 mmHg further distal (15 cm) within the main PA branch. Moderate to severe lesions of the tunica media of the PAs were observed in seven horses, but a correlation with PWV could not be established yet. Pulmonary artery PWV may be determined in standing horses. The technique described may allow further investigation of the effect of calcification of large PAs in the pathogenesis of equine pulmonary circulatory disorders.NEW & NOTEWORTHY Pulmonary artery pulse wave velocity was determined safely in standing sedated horses. The technique described may allow further investigation of the effect of calcification of large pulmonary arteries in the pathogenesis of pulmonary circulatory disorders in horses.

Ultrasonographic detection of early atrophy of the intrinsic laryngeal muscles of horses.

OBJECTIVE: To describe the ultrasonographic changes in the cricoarytenoideus dorsalis (CAD) and cricoarytenoideus lateralis (CAL) muscles of horses before and at various times during the 32 weeks after unilateral neurectomy of the right recurrent laryngeal nerve. ANIMALS: 28 healthy Standardbreds. PROCEDURES: For each horse, the appearance of the CAD and CAL muscles on the right (neurectomized) and left (control) sides was serially monitored ultrasonographically by percutaneous (CAD and CAL) and transesophageal (CAD) approaches. The ultrasonographic images were assessed to determine the mean pixel intensity, muscle thickness, and appearance grade, and comparisons were made between the muscles of the neurectomized and control sides. RESULTS: The muscle appearance grade and mean pixel intensity for the CAL and CAD muscles on the neurectomized side were significantly increased by 2 and 4 weeks, respectively, after the neurectomy. The transesophageal approach enhanced the ultrasonographic visibility of the CAD muscle and allowed us to detect a significant decrease in the thickness of the CAD muscle on the neurectomized side over time, compared with thickness of the CAD muscle on the control side. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested ultrasonography can be used to successfully assess the CAL and CAD muscles of horses. A qualitative grading scheme was sufficient for successful detection and monitoring of muscle atrophy and reduced the need for image standardization. The transesophageal approach described for assessment of the CAD muscle warrants further investigation.

Cytokine induction in pulmonary airways of horses with heaves and effect of therapy with inhaled fluticasone propionate.

Work in humans and laboratory animals has identified a central role for cytokines and chemokines in development and persistence of lower airway inflammation. The objectives of this study were to determine interleukin (IL)-1 beta, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, interferon (IFN)-gamma and tumor necrosis factor (TNF)-alpha induction in bronchoalveolar lavage (BAL) of control horses and horses with heaves both during remission and exacerbation of the disease, and to determine the effect of therapy with inhaled fluticasone propionate on the cytokine profile of horses with heaves. IL-1 beta and TNF-alpha mRNA expression was significantly higher in horses with heaves after exposure to moldy hay compared to either values obtained during clinical remission or to healthy controls. IL-8 mRNA expression and protein concentrations were significantly higher in horses with heaves than in controls. Both IL-4 and IFN-gamma mRNA expression was increased at various times in heaves-susceptible horses compared to controls. IL-2, IL-5 and IL-10 mRNA expression was not detected in BAL cells of either group. Therapy with inhaled fluticasone propionate after induction of a severe heaves exacerbation resulted in complete resolution of clinical signs, normalization of pulmonary function tests, and significant decrease in BAL neutrophilia. This was associated with a significant decrease in IL-4 mRNA expression and increase in IFN-gamma/IL-4 ratio in horses with heaves. These results demonstrate the clinical efficacy of inhaled fluticasone propionate for the treatment of heaves and suggest a role for cytokines in the development of lower airway inflammation in heaves-susceptible horses.