Evaluation of the airway mechanics of modified toggle laryngoplasty constructs using a vacuum chamber airflow model.

OBJECTIVE: To evaluate the airway mechanics of modified toggle LP constructs in an airflow chamber model and compare these to the airway mechanics of standard LP constructs. STUDY DESIGN: Ex-vivo experimental study. SAMPLE POPULATION: Fifty-one equine cadaveric larynges. METHODS: Bilateral LP constructs were performed using a modified toggle (n = 23) or a standard (n = 21) LP technique. Constructs were tested in an airflow model before and after cyclic loading which was designed to mimic postoperative swallowing. The cross-sectional area (CSA), peak translaryngeal airflow (L/s), and impedance (cmH2 0/L/s) were determined and compared between LP constructs before and after cycling. RESULTS: The mean CSA of the rima glottidis of the modified toggle LP constructs was 15.2 ± 2.6 cm2 before and 14.7 ± 2.6 cm2 after cyclic loading, and the mean CSA of the rima glottidis of the standard LP constructs was 16.4 ± 2.9 cm2 before and 15.7 ± 2.8 cm2 after cyclic loading. The modified toggle LP constructs had similar peak translaryngeal impedance before and after cyclic loading (p = .13); however, the standard LP constructs had higher peak translaryngeal impedance after cyclic loading (p = .02). CONCLUSION: The modified toggle and standard LP constructs had comparable airway mechanics in an ex-vivo model. CLINICAL SIGNIFICANCE: Further investigation is warranted to determine the extent to which the modified toggle LP technique restores normal airway function in horses with RLN.

Airway Diagnostics: Bronchoalveolar Lavage, Tracheal Wash, and Pleural Fluid.

Indications for bronchoalveolar lavage, tracheal wash, and thoracocentesis for the diagnosis of respiratory diseases are discussed. Each technique is described in detail and illustrated by videos. Sample handling, preparation and evaluation are reviewed. The advantages and limitations of bronchoalveolar lavage and tracheal wash procedures as well as a critical comparison between the 2 techniques for equine asthma diagnosis are presented. Finally, validated cut-off values for equine asthma diagnosis are reviewed.

A wearable real-time particulate monitor demonstrates that soaking hay reduces dust exposure.

BACKGROUND: Affordable particulate matter (PM) monitors suitable for use on horses will facilitate the evaluation of PM mitigation methods and improve the management of equine asthma. OBJECTIVE: Calibrate a real-time wearable PM monitor (Black Beauty [BB]) and compare the PM exposures of horses fed dry or soaked hay. STUDY DESIGN: Laboratory calibration; complete cross-over feed trial. METHODS: Side-by-side sampling with BB monitors and tapered element oscillating microbalances (TEOMs) was performed under varying concentrations of PM from alfalfa hay. Linear regression was used to derive a calibration formula for each unit based on TEOM PM measurements. Precision was evaluated by calculating the coefficient of variation and pairwise correlation coefficients between three BB monitors. PM exposure was measured at the breathing zone of 10 horses for 8 h after they were fed dry or soaked hay. Repeated measures generalised linear models were constructed to determine the effect of hay treatment and measurement duration (initial 20-min vs. 8-h) upon exposure to PM with diameters smaller than or equal to 10 µm (PM10) and 2.5 µm (PM2.5). RESULTS: BB monitor PM2.5 and PM10 measurements were linearly correlated with TEOM data (coefficient of determination r2 > 0.85 and r2 > 0.90 respectively), but underestimated PM2.5 mass concentrations by a factor of 4 and PM10 concentrations by a factor of 44. Measures from the three BB monitors had a coefficient of variation <15% and pairwise r > 0.98. Feeding soaked hay significantly reduced average PM2.5 exposures (20-min: dry: 160 µg/m3, soaked: 53 µg/m3, p < 0.0001; 8-h: dry: 76 µg/m3, soaked: 31 µg/m3, p = 0.0008) and PM10 exposures (20-min: dry: 2829 µg/m3, soaked: 970 µg/m3, p < 0.0001; 8-h: dry: 1581 µg/m3, soaked: 488 µg/m3, p = 0.008). MAIN LIMITATIONS: No health outcome measures were collected. CONCLUSIONS: With appropriate corrections, the BB monitor can be used to estimate horse PM exposure. While 20-min measurements yielded higher estimates of exposure than 8-h measurements, both intervals demonstrate that soaking hay reduces PM exposures by more than 50%.

Effects of low-dust forages on dust exposure, airway cytology, and plasma omega-3 concentrations in Thoroughbred racehorses: A randomized clinical trial.

BACKGROUND: Racehorses commonly develop evidence of mild asthma in response to dust exposure. Diets deficient in omega-3 polyunsaturated fatty acids (Ω-3) might exacerbate this response. HYPOTHESIS: To compare dust exposure, bronchoalveolar lavage fluid (BALF) cytology, and plasma Ω-3 and specialized pro-resolving mediators (SPM) concentrations amongst racehorses fed dry hay, steamed hay, and haylage. ANIMALS: Forty-three Thoroughbred racehorses. METHODS: Prospective clinical trial. Horses were randomly assigned to be fed dry hay, steamed hay, or haylage for 6 weeks. Measures of exposure to dust in the breathing zone were obtained twice. At baseline, week-3, and week-6, BALF cytology was examined. Plasma lipid profiles and plasma SPM concentrations were examined at baseline and week 6. Generalized linear mixed models examined the effect of forage upon dust exposure, BALF cytology, Ω-3, and SPM concentrations. RESULTS: Respirable dust was significantly higher for horses fed hay (least-square mean ± s.e.m. 0.081 ± 0.007 mg/m3 ) when compared with steamed hay (0.056 ± 0.005 mg/m3 , P = .01) or haylage (0.053 ± 0.005 mg/m3 , P < .01). At week 6, BALF neutrophil proportions in horses eating haylage (3.0% ± 0.6%) were significantly lower compared with baseline (5.1 ± 0.7, P = .04) and horses eating hay (6.3% ± 0.8%, P < .01). Plasma eicosapentaenoic acid to arachidonic acid ratios were higher in horses eating haylage for 6 weeks (0.51 ± 0.07) when compared with baseline (0.34 ± 0.05, P < .01) and horses eating steamed (0.24 ± 0.02, P < .01) or dry hay (0.25 ± 0.03, P < .01). CONCLUSIONS AND CLINICAL IMPORTANCE: Steamed hay and haylage reduce dust exposure compared with dry hay, but only haylage increased the ratio of anti-inflammatory to pro-inflammatory lipids while reducing BAL neutrophil proportions within 6 weeks.

Effect of Lavage Solution Type on Bronchoalveolar Lavage Fluid Cytology in Clinically Healthy Horses.

Equine bronchoalveolar lavage (BAL) is usually performed with 250-500 mL of isotonic saline at pH 5.5. The acidic pH of saline may cause an increase in airway neutrophil count 48 h after BAL. Other isotonic solutions such as Ringer's solution, phosphate-buffered saline (PBS) or Plasma-Lyte 148® have a neutral pH of 7.4 and might be a better choice for BAL by not provoking inflammation and the influx of neutrophils into airways. BAL was performed in four healthy horses in four different lung lobes using four different solutions in a randomized crossover design. In each lobe, BAL was performed twice with a 48 h interval using 250 mL of solution. Automated total nucleated cell counts (TNCs) were recorded, and differential cell counts in lavage fluid were determined by two investigators blinded to treatments. The mean volume of BAL fluid retrieved was 51 ± 14%. The mean neutrophil percentage (%N) increased from 1.5 ± 0.9% to 14.7 ± 9.6% at 48 h (p < 0.001) but was not significantly affected by the solution used or the lung lobe sampled. In conclusion, in this study, the influx of neutrophils into airways after BAL was independent of the type of isotonic solution used and the lung lobe sampled. Saline remains an appropriate solution for BAL in horses.

Lipidomic analysis of surfactant and plasma from horses with asthma and age-matched healthy horses.

OBJECTIVE: To perform lipidomic analysis of surfactant and plasma from asthmatic and healthy horses. ANIMALS: 30 horses with clinical signs of asthma and 30 age-matched control horses. PROCEDURES: Detailed history, physical examination, CBC, and bronchoalveolar lavage fluid (BALF) cytologies were obtained. Asthmatic horses were grouped based on their BALF inflammatory profile: severe equine asthma (SEA), mild equine asthma with neutrophilic airway inflammation (MEA-N), or mild equine asthma with eosinophilic airway inflammation (MEA-E). Each asthma group was assigned its own age-matched control group. Lipidomic analysis was completed on surfactant and plasma. Surfactant protein D (SP-D) concentrations were measured in serum and BALF. RESULTS: SEA surfactant was characterized by a phospholipid deficit and altered composition (increased ceramides, decreased phosphatidylglycerol, and increased cyclic phosphatidic acid [cPA]). In comparison, MEA-N surfactant only had a decrease in select phosphatidylglycerol species and increased cPA levels. The plasma lipidomic profile was significantly different in all asthma groups compared to controls. Specifically, all groups had increased plasma phytoceramide. SEA horses had increased plasma cPA and diacylglycerol whereas MEA-N horses only had increased cPA. MEA-E horses had increases in select ceramides and dihydrocermides. Only SEA horses had significantly increased serum SP-D concentrations. CLINICAL RELEVANCE: The most significant surfactant alterations were present in SEA (altered phospholipid content and composition); only mild changes were observed in MEA-N horses. The plasma lipidomic profile was significantly altered in all groups of asthmatic horses and differed among groups. Data from a larger population of asthmatic horses are needed to assess implications for diagnosis, prognosis, and treatment.

Comparison of genomic and proteomic data in recurrent airway obstruction affected horses using Ingenuity Pathway Analysis®.

BACKGROUND: Recurrent airway obstruction (RAO) is a severe chronic respiratory disease affecting horses worldwide, though mostly in the Northern hemisphere. Environmental as well as genetic factors strongly influence the course and prognosis of the disease. Research has been focused on characterization of immunologic factors contributing to inflammatory responses, on genetic linkage analysis, and, more recently, on proteomic analysis of airway secretions from affected horses. The goal of this study was to investigate the interactions between eight candidate genes previously identified in a genetic linkage study and proteins expressed in bronchoalveolar lavage fluid (BALF) collected from healthy and RAO-affected horses. The analysis was carried out with Ingenuity Pathway Analysis® bioinformatics software. RESULTS: The gene with the greatest number of indirect interactions with the set of proteins identified is Interleukin 4 Receptor (IL-4R), whose protein has also been detected in BALF. Interleukin 21 receptor and chemokine (C-C motif) ligand 24 also showed a large number of interactions with the group of detected proteins. Protein products of other genes like that of SOCS5, revealed direct interactions with the IL-4R protein. The interacting proteins NOD2, RPS6KA5 and FOXP3 found in several pathways are reported regulators of the NFκB pathway. CONCLUSIONS: The pathways generated with IL-4R highlight possible important intracellular signaling cascades implicating, for instance, NFκB. Furthermore, the proposed interaction between SOCS5 and IL-4R could explain how different genes can lead to identical clinical RAO phenotypes, as observed in two Swiss Warmblood half sibling families because these proteins interact upstream of an important cascade where they may act as a functional unit.

Lung volume reduction by bronchoscopic administration of steam.

RATIONALE: At present, bronchoscopic approaches to lung volume reduction (LVR) create airway obstruction to achieve parenchyma collapse, avoiding many risks of surgical LVR. However, LVR by these methods is limited by temporary or incomplete collapse and/or residual atelectatic and scarred tissue volumes. Heat-induced ablation of lung tissue is currently under investigation as an alternative LVR methodology. OBJECTIVES: We hypothesized that bronchoscopic steam injection can produce safe and effective LVR, and explored potential mechanisms for the effects. METHODS: Steam treatments were applied bilaterally to six cranial lobe segments of large dogs. For series 1, 14 dogs received one of three target heat dose levels (1, 4, or 8 cal · ml⁻¹ segment volume), and then 3 months of follow-up including pulmonary function testing and monitoring for complications. For series 2, 12 dogs received a single target dose (4 cal · ml⁻¹) or sham, similar follow-up, and then assessment of lobar mass, volume, and blood flow. Vapor content of series 2 steam was 40% greater than for series 1 (similar heat dose) to attempt more peripheral heat delivery. MEASUREMENTS AND MAIN RESULTS: Nineteen of 20 treatment animals survived with minimal evidence of serious risks or reduced pulmonary function testing volumes, but 1 died from pneumothorax 5 days post-treatment. Postmortem processing of animals that survived as planned revealed obvious dose-dependent lobe reductions, additional evidence of risks, and blood flow reduction that occurred immediately post-treatment. CONCLUSIONS: Bronchoscopic administration of steam is a potentially safe means to achieve LVR, but substantial risks are present and further research is recommended.

The effect of lower airway inflammation on inflammatory cytokine gene expression in bronchoalveolar lavage fluid and whole blood in racing Thoroughbreds.

BACKGROUND: Immunological mechanisms involved in the pathogenesis of mild to moderate equine asthma (MEA) are not completely understood. There are limited data on bronchoalveolar lavage fluid (BALF) and blood inflammatory cytokine profiles in racehorses with MEA, and the effect of racing on inflammatory cytokines is unknown. HYPOTHESIS/OBJECTIVES: We hypothesized that inflammatory cytokine gene expression in BALF and resting blood would be higher in racehorses with lower airway inflammation compared to healthy controls, and that gene expression in blood collected immediately post-race would be increased compared to resting blood in racehorses with lower airway inflammation. ANIMALS: 38 racing Thoroughbreds (samples: 30 resting blood, 22 post-race BALF, 41 post-race blood). METHODS: Prospective observational study. Inflammatory cytokine gene expression was determined in resting blood, post-race BALF and post-race blood from racehorses with lower airway inflammation and controls. RESULTS: Lower airway inflammation was diagnosed in 79 % of racehorses (23 % neutrophilic, 67 % mastocytic, and 10 % mixed). There was no difference in gene expression in BALF or resting blood between racehorses with lower airway inflammation and controls. IL-8 gene expression was higher in post-race blood compared to resting peripheral blood, regardless of disease (p = 0052). BALF neutrophil proportions increased with increasing IL-1ß gene expression in all sample types (p = 0.0025). BALF mast cell proportions increased with increasing TNF-α gene expression in post-race blood (p = 0.015). CONCLUSIONS AND CLINICAL IMPORTANCE: Lower airway inflammation was common in a population of racehorses without respiratory signs or exercise intolerance. Exercise alone increased peripheral blood IL-8 gene expression. Inflammatory cytokine gene expression was not increased in BALF or resting blood in horses with subclinical lower airway inflammation, precluding its diagnostic utility in clinical practice.

Effects of forages, dust exposure and proresolving lipids on airway inflammation in horses.

OBJECTIVE: To investigate the role of omega-3 polyunsaturated fatty acids (Ω-3)-derived proresolving lipid mediators (PRLM) in the resolution of mild airway inflammation in horses. ANIMALS: 20 horses with mild airway inflammation. PROCEDURES: Horses previously eating hay were fed hay pellets (low Ω-3 content; n = 10) or haylage (high Ω-3 content; 9) for 6 weeks. Dust exposure was measured in the breathing zone with a real-time particulate monitor. Bronchoalveolar lavage (BAL) was performed at baseline, week 3, and week 6. The effect of PRLM on neutrophil apoptosis and efferocytosis was examined in vitro. BAL fluid inflammatory cell proportions, apoptosis of circulating neutrophils, efferocytosis displayed by alveolar macrophages, and plasma lipid concentrations were compared between groups fed low and high amounts of Ω-3 by use of repeated measures of generalized linear models. RESULTS: Dust exposure was significantly higher with hay feeding, compared to haylage and pellets, and equivalent between haylage and pellets. BAL fluid neutrophil proportions decreased significantly in horses fed haylage (baseline, 11.8 ± 2.4%; week 6, 2.5 ± 1.1%) but not pellets (baseline, 12.1 ± 2.3%; week 6, 8.5% ± 1.7%). At week 6, horses eating haylage had significantly lower BAL neutrophil proportions than those eating pellets, and a significantly lower concentration of stearic acid than at baseline. PRLM treatments did not affect neutrophil apoptosis or efferocytosis. CLINICAL RELEVANCE: Despite similar reduction in dust exposure, horses fed haylage displayed greater resolution of airway inflammation than those fed pellets. This improvement was not associated with increased plasma Ω-3 concentrations. Feeding haylage improves airway inflammation beyond that due to reduced dust exposure, though the mechanism remains unclear.

Effect of furosemide and furosemide-carbazochrome combination on exercise-induced pulmonary hemorrhage in Standardbred racehorses.

The objective was to quantify the effect of furosemide and carbazochrome on exercise-induced pulmonary hemorrhage (EIPH) in Standardbred horses using red blood cell count and hemoglobin concentration in bronchoalveolar lavage (BAL) fluid. Six healthy Standardbred horses with prior evidence of EIPH performed a standardized treadmill test 4 h after administration of placebo, furosemide, or furosemide-carbazochrome combination. Red blood cell (RBC) counts and hemoglobin concentrations were determined on the BAL fluid. The RBC count in BAL ranges were (2903-26,025 cells/microL), (45-24,060 cells/microL), and (905-3045 cells/microL) for placebo, furosemide, and furosemide-carbazochrome, respectively. Hemoglobin concentration ranges were (0.03-0.59 mg/mL), (0.01-0.55 mg/mL), and (0.007-0.16 mg/mL) for placebo, furosemide, and furosemide-carbazochrome groups, respectively. No significant differences were detected among treatments. However, there was great variability among horses, suggesting that a larger sample size or better selection of horses was needed.

Cholangiectasis and duodenal diverticulosis in a farm-raised elk (Cervus elaphus).

A 6-year-old male elk presented in August with a 4-month history of weight loss and a 1-day history of being recumbent and unable to rise. The elk's body condition score was 1.5/5. Hematology and blood chemistry showed an inflammatory leukogram, mild electrolyte abnormalities, and elevated liver enzyme activities. Because of poor prognosis, the owner elected euthanasia. On necropsy, 8 diverticula were in the duodenum distal to the common bile duct, which was dilated and filled with feed material. Many intrahepatic bile ducts were dilated up to 5 cm, were filled with ingesta and gritty material, and had walls thickened up to 1.5 mm. On histologic examination, mural thickening of dilated bile ducts was because of increased fibrous connective tissue with inflammatory cell infiltration and hyperplastic and hypertrophic epithelial lining. Portal tracts diffusely contained hyperplastic bile ducts and had increased amounts of fibrous connective tissue. Abscesses that contained bacteria were scattered throughout the liver. Duodenal diverticula lacked the tunica muscularis, and the muscularis mucosa was hypertrophied. Caudal to some diverticula, the duodenal lumen was narrowed. An additional finding was embolic pneumonia with fungi morphologically and immunohistochemically consistent with Aspergillus spp.

An observational study of environmental exposures, airway cytology, and performance in racing thoroughbreds.

BACKGROUND: Mild equine asthma is presumed to arise in response to environmental exposures but the relative impact of differing inflammatory phenotypes upon performance are largely unexplored. HYPOTHESES: Airway inflammation negatively affects performance and cytological phenotype varies with environmental exposure. ANIMALS: Thoroughbred racehorses in active training and racing. METHODS: Thoroughbreds were recruited 24-48 hours before racing. Each horse was eligible for re-enrollment with each race entry. Within one hour of race completion, physical examination, respiratory endoscopy, and BAL were performed. Respirable and inhalable dust, respirable endotoxin, and respirable ß-glucan exposures were measured at the breathing zone within one week after racing. Controlling for age, trainer, and pulmonary hemorrhage, the relationship between performance, bronchoalveolar lavage fluid (BALF) cytology, and measures of exposure were modeled. RESULTS: Performance and BALF data were collected on 64 individual horses from 8 stables for a total of 98 race performances and 79 dust exposure assessments. Evidence of mild equine asthma was found in 80% (78/98) of BALF samples from 52/64 horses. For each percent increase in BALF mast cell and neutrophil proportions, speed figures were reduced by 2.9 (P = .012) and 1.4 (P = .046) points, respectively. Respirable dust concentration was associated with BALF neutrophil proportions (P = .015). Bronchoalveolar lavage fluid mast cell proportions were only associated with respirable ß-glucan exposures (P = .030). CONCLUSIONS AND CLINICAL IMPORTANCE: Mild equine asthma is common in racing horses and negatively impacts performance. The data support that respirable, rather than inhalable, dust exposure measures are pertinent to equine airway health.

Hypertrichosis in a horse with alimentary T-cell lymphoma and pituitary involvement.

A 13-year-old Quarterhorse mare had a 6-month history of diarrhea, progressive weight loss, and lethargy. At presentation the mare was hirsute, had hyperhidrosis, and abnormal fat distribution in addition to severe diarrhea. A presumptive clinical diagnosis of protein-losing enteropathy and pituitary pars intermedia dysfunction was made. T-cell lymphoma was diagnosed in a rectal biopsy specimen. The owner elected to euthanize the mare because of poor prognosis and the severity of the disease. At necropsy, the mare had hypertrichosis and the pituitary gland was diffusely enlarged. Histologically, neoplastic lymphocytes infiltrated the gastrointestinal mucosa, mesenteric lymph nodes, and the pituitary gland. In addition, there was hyperplasia of the pituitary gland pars intermedia. Pituitary adenoma was not present. Hypertrichosis in this case could have been triggered by a combination of adenomatous hyperplasia of pars intermedia and lymphoma resulting in disruption of the hypothalamic dopaminergic tone or disruption of the hypothalamic thermoregulatory center.

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.

DNA binding activity of transcription factors in bronchial cells of horses with recurrent airway obstruction.

Horses with recurrent airway obstruction (RAO) present many similarities with human asthmatics including airway inflammation, hyperresponsiveness, reversible obstruction, and increased NF-kappaB expression. Studies in experimental asthma models have shown that transcriptions factors such as activator protein-1 (AP-1), GATA-3, cyclic AMP response element binding protein (CREB) and CAAT/enhancer binding protein (C/EBP) may also play an important role in airway inflammation. The purpose of this study was to measure DNA binding activity of these transcription factors in the airways of horses with RAO and to compare it to pulmonary function and bronchoalveolar lavage fluid (BALF) cytology. Seven horses with RAO and six control animals were studied during a moldy hay challenge and after 2 months at pasture. Pulmonary function, BALF cytology and transcription factors' activities in bronchial brushings were measured during hay and pasture exposures. During moldy hay challenge, RAO-affected horses developed severe airway obstruction and inflammation and a significantly higher airway AP-1 binding activity than in controls. After 2 months on pasture, pulmonary function and airway AP-1 binding activity were not different between RAO and control horses. The DNA binding activity of CREB in airways of RAO-affected horses increased significantly after 2 months at pasture and became higher than in controls. A significant positive correlation was detected between AP-1 binding activity and indicators of airway obstruction and inflammation. Airway GATA-3, CEBP and CREB binding activities were negatively correlated with indices of airway obstruction. However, contrarily to CREB binding activity, GATA-3 and CEBP binding activities were not different between RAO and control horses and were unaffected by changes in environment. These data support the view that AP-1 and CREB play a role in modulating airway inflammation in horses with RAO.

Effect of beclomethasone dipropionate and dexamethasone isonicotinate on lung function, bronchoalveolar lavage fluid cytology, and transcription factor expression in airways of horses with recurrent airway obstruction.

Glucocorticoid (GC) therapy is recognized to be effective for the treatment of recurrent airway obstruction (RAO) in horses. Anti-inflammatory properties of GC are thought to be mediated by suppression of inflammatory gene expression via inhibition of transcription factors such as nuclear factor-kappaB (NF-kappaB) and activator protein-1 (AP-1). The purpose of this study was to evaluate the effect of low-dose inhaled beclomethasone dipropionate and injectable dexamethasone 21-isonicotinate on clinical signs, pulmonary function, airway cytology, and activity of NF-kappaB and AP-1 in bronchial cells of RAO-affected horses. Seven horses with RAO were exposed to moldy hay until they developed airway obstruction on 3 separate occasions. In a crossover design, they were then treated with a placebo (injection on day 1), inhaled beclomethasone (500 microg q12h for 10 days), or dexamethasone (0.06 mg/kg, IM on day 1) and monitored for 10 days. Pulmonary function, bronchoalveolar lavage fluid cytology, and NF-kappaB and AP-1 activity in bronchial brushing cells were measured before (day 1) and after treatment (day 10). Treatment with beclomethasone resulted in significantly improved pulmonary function of RAO-affected horses compared with placebo and dexamethasone treatments. However, none of the treatments had an effect on bronchoalveolar lavage fluid cytology or NF-kappaB and AP-1 activity. These findings reveal that, in a model of severe RAO, the benefits of low-dose inhaled beclomethasone on pulmonary function are not accompanied by a decrease in airway inflammatory cells or a suppression of transcription factors NF-kappaB and AP-1 DNA-binding activity.

Investigation and control of an outbreak of salmonellosis caused by multidrug-resistant Salmonella typhimurium in a population of hospitalized horses.

An outbreak of salmonellosis in a population of hospitalized horses resulted in the closure of a teaching hospital for a period of 10 weeks. Fecal samples were collected from suspected cases and cultured for Salmonella. Salmonella isolates were characterized using antimicrobial susceptibility testing, pulsed-field gel electrophoresis (PFGE) and phage typing. Thirty-three cases of infection by a multidrug-resistant strain of S. typhimurium were detected. The index case was admitted on 26 August 1999. Fifteen (45%) cases occurred between April and June 2000. PFGE results suggested that this strain of S. typhimurium might have been introduced into the hospital environment by a foal presenting with diarrhea. The hospital was closed on June 13, and intensive environmental cleaning and disinfection were completed. Enforcement of infectious disease control protocols in hospitals and environmental and patient surveillance is needed to prevent outbreaks of salmonellosis.

Evaluation of a PCR to detect Salmonella in fecal samples of horses admitted to a veterinary teaching hospital.

The diagnostic accuracy of a PCR used to identify horses shedding Salmonella spp. in their feces during hospitalization was estimated, relative to bacterial culture of serially collected fecal samples, using longitudinal data. Five or more fecal samples were collected from each of 116 horses admitted as inpatients, for reasons other than gastrointestinal disease, between July 26, 2001 and October 25, 2002. All 873 fecal samples collected were tested with a PCR based on oligonucleotide primers defining a highly conserved segment of the histidine transport operon gene of Salmonella typhimurium, and each sample was cultured for Salmonella spp. One or more samples from 87 (75%) horses were PCR positive, and Salmonella was cultured from 1 or more samples from 11 (9.5%) horses. All culture-positive horses had at least 1 PCR-positive result, whereas only 29 (28%) culture-negative horses were PCR negative on all fecal samples tested. The PCR was most specific, relative to bacterial culture of serially collected fecal samples, when used to test samples from Quarterhorse or breeds other than Thoroughbred or Standardbred, or from clinical (vs. healthy, accompanying horses) cases. Overall, the PCR had the greatest agreement (70%), compared with bacterial culture of serially collected fecal samples, using a cutoff of 2 or more positive PCR test results to define a Salmonella-positive horse. The reasons why some fecal samples, from which Salmonella organisms cannot be isolated, are PCR positive need to be determined before the PCR can be incorporated into Salmonella surveillance programs for hospitalized equine populations.

Climatic and aeroallergen risk factors for chronic obstructive pulmonary disease in horses.

OBJECTIVE: To estimate the association between climate and airborne pollen and fungal factors and chronic obstructive pulmonary disease (COPD) in horses. SAMPLE POPULATION: Data from 1,444 horses with a diagnosis of COPD. PROCEDURE: The Veterinary Medical Database was used to identify records of horses admitted to veterinary teaching hospitals in the United States and Canada between 1990 and 1999. Rainfall, mean minimum and maximum temperature, and maximum monthly pollen and fungal spore (mold) counts recorded at the city closest to where the hospital is located were identified for each month data were reported to the Veterinary Medical Database. Associations between climatic and aeroallergen data and monthly prevalence of COPD were estimated by use of cross-correlation and logistic regression models. RESULTS: Significant positive correlations were found between prevalence of COPD and rainfall 3 months previously, minimum temperature 1 and 2 months previously, total pollen counts measured 3 months previously, and total mold counts measured during the same month and 1 month previously. CONCLUSIONS AND CLINICAL RELEVANCE: Outdoor aeroallergens and climatic factors may contribute to the occurrence of COPD in horses.