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Abstract

Objective

To determine whether oral administration of erythromycin alters the inflammatory response to bronchoalveolar lavage (BAL) in young horses.

Animals

12 healthy, unweaned, mixed-breed foals of either sex, between 2 and 4 months old.

Procedure

BAL was performed; 250 ml of phosphate-buffered saline solution (300 mOsm, pH 7.4) was administered in 50-ml aliquots. Foals were carefully monitored for 4 days, then erythromycin base (25 mg/kg of body weight, PO, q 12 h) was given to foals of the treated group. After 4 days, foals were re-anesthetized, and the same lung was relavaged. Cytologic examination was performed on BAL fluid (BALF) samples from both groups of foals. At 12 hours after administration of the final dose, erythromycin A and anhydroerythromycin A concentrations were determined in plasma of treated foals.

Results

In the second BALF sample from the same lung of control foals, percentage of neutrophils was significantly increased (3 ± 38.0%), compared with that from erythromycin-treated foals (4.88 ± 3.66%, P < 0.05), and was associated with apparent decrease in the ability of BALF cells from erythromycin-treated foals to migrate toward a chemoattractant source. Significantly fewer BALF cells adhered to a cell culture substratum after erythromycin treatment of foals. Erythromycin A was not detected in plasma of any treated foal at the time of the second BAL; anhydroerythromycin A, a degradation product of erythromycin, was detected in plasma of 5 of 6 foals (mean concentration, 0.2 ± 0.06 µg/ml).

Conclusion and Clinical Relevance

BAL induces neutrophilic inflammation, which persists for at least 4 days in the lungs of young horses. Erythromycni (25 mg/kg, PO, q 12 h) diminishes this inflammatory response through a mechanism that may involve alteration of BALF cell function. Degradation of erythromycin to biologically active products or presence of parent drug in pulmonary secretions may be responsible for alterations in pulmonary lavage cell Chemotaxis and adherence. Erythromycin administered orally to foals at clinically relevant doses appears to have nonantimicrobial effects that may interfere with host cell metabolism and decrease inflammatory reponses in airways. (Am J Vet Res 1997;58:56–61)

Free access
in American Journal of Veterinary Research

Summary

Effects of triamcinolone acetonide (ta) on pulmonary function, bronchoalveolar lavage cytologic features and serum cortisol concentration, were studied in 5 control horses and 5 horses with chronic obstructive pulmonary disease (copd). In experiment 1, horses were brought in from pasture 3 weeks before administration of 1 injection of ta (0.09 mg/kg of body weight, im), and were stabled in dusty conditions throughout the experimental period. Measurements of respiratory rate (f), tidal volume, minute ventilation, expiratory-to-inspiratory time ratio, maximal change in transpulmonary pressure (ΔPL), pulmonary resistance (RL), and dynamic compliance (Cdyn) were obtained during quiet breathing, immediately before (baseline) and 1, 2, 3, 5, and 9 weeks after administration of ta. Pulmonary airway cells were collected by bronchoalveolar lavage while horses were at pasture, at baseline, and 2, 5, and 9 weeks after ta administration. Serum cortisol concentration was measured before and after adrenocortical stimulation with 100 IU of adrenocorticotropic hormone, 1 week prior to ta administration, and 4 and 8 weeks thereafter. In experiment 2, 4 months after ta injection, pulmonary function measurements were repeated in all horses immediately before and 30 minutes after administration of atropine (0.015 mg/kg, iv), to evaluate the reversibility of airway obstruction.

In experiment 1 at baseline, COPD-affected horses had significantly (P < 0.05) higher values than did controls for f, ΔPL, RL, and percentage of neutrophils, and had lower values for Cdyn and percentage of lymphocytes and macrophages. There were significant reductions in ΔPL and RL, and increase in macrophage percentage after ta administration in copd-affected horses only. The degree and duration of these changes varied among individual copd-affected horses, but ΔPL, and RL, values had returned to or were above baseline in all horses 5 weeks after treatment. Baseline cortisol concentration was decreased 4 weeks after ta administration, but the mean increase in cortisol values after adrenocorticotropic hormone stimulation was similar to that observed prior to treatment.

In experiment 2, values of ΔPL, RL, and Cdyn, after atropine administration were similar to those of controls in the 2 copd-affected horses that had improved most after ta, but were only partially improved in the 3 other horses, indicating possible irreversible lesions in the latter.

Free access
in American Journal of Veterinary Research

Abstract

Objective

To determine cytologic changes in horses with recurrent airway obstruction (heaves) after administration of aerosolized beclomethasone dipropionate and dexamethasone parenterally.

Animals

6 horses with inducible and reversible heaves.

Procedure

Episodes of heaves were induced by exposure to moldy hay and straw for 7 days. Horses were assigned to treatment groups (aerosolized beclomethasone, parenterally administered dexamethasone, aerosolized propellant), and pulmonary inflammation was evaluated by serial cytologic examination of bronchoalveolar lavage (BAL) fluid samples obtained on days 0, 7, 10, 14, and 21. Total and differential cell counting and phenotypic analysis of lymphocyte subpopulations in BAL fluid were performed.

Results

7 days of natural challenge induced neutrophilic inflammation. Neutrophil counts in BAL fluid were reduced in beclomethasone- and dexamethasone-treated horses on days 10 and 14 but rebounded to pretreatment values on day 21. The proportion of proinflammatory lymphocyte subpopulations (CD4+ and B+) and MHC class-II antigen expression were increased on days 14 and 21 in propellant-treated horses, compared with beclomethasone- and dexamethasone-treated horses.

Conclusions

Aerosolized beclomethasone attenuated neutrophilic pulmonary inflammation and prevented alteration in lymphocyte subpopulations in horses with heaves. Results were similar to the response associated with parenterally administered dexamethasone. Short-term administration of aerosolized beclomethasone without minimizing environmental allergen exposure is not expected to provide prolonged anti-inflammatory benefit for horses with heaves. (Am J Vet Res 1998;59:1033–1038)

Free access
in American Journal of Veterinary Research

Bronchoalveolar lavage fluid samples were collected as described. 22 Briefly, a sterile 36-inch flexible 10F catheter d with a 3-mL balloon cuff was used to collect BALF samples from preweaned calves, and a sterile 59-inch flexible 24F catheter d with a 30-mL

Full access
in American Journal of Veterinary Research

after drug administration, and samples at 36 and 48 hours were collected by direct venipuncture of the left jugular vein. Bronchoalveolar lavage was performed 2, 4, 8, and 24 hours after drug administration. Experiment 2 involved intragastric

Full access
in American Journal of Veterinary Research

Abstract

Objectives

To determine whether tilmicosin alters neutrophil infiltration or function, induces neutrophil apoptosis, and affects accumulation of leukotriene B4 (LTB4) or tumor necrosis factor-alpha (TNF-α) in lungs of calves experimentally infected with Pasteurella haemolytica.

Animals

12 weight-ranked Holstein calves.

Procedure

Calves were given 25% propylene glycol vehicle (n = 5) or tilmicosin (10 mg/kg of body weight; n = 6) subcutaneously, 18 hours and 15 minutes before intratracheal infection with 2 × 108 P haemolytica organisms. Two unmanipulated calves served as controls in some experiments. Rectal temperatures were recorded 15 minutes before, and at 3- hour intervals after infection for 24 hours. Samples obtained from bronchoalveolar lavage performed 3 and 24 hours after infection were used to assess colonization by P haemolytica, and neutrophil infiltration. Neutrophil phagocytosis of P haemolytica, membrane leakage as determined by trypan blue exclusion, oxidative function as determined by nitro blue tetrazolium reduction, and apoptosis, using electron microscopy and DNA fragmentation ELISA, were determined. Soluble TNF-α and LTB4 were measured from supernatants from bronchoalveolar lavage samples, using ELISA.

Results

Treatment with tilmicosin resulted in significant (P< 0.05) clearance of P haemolytica and neutrophil apoptosis at 3 hours, and decreased concentration of LTB4 at 24 hours. Rectal temperatures, neutrophil infiltration, phagocytosis, oxidative functions, membrane leakage, and soluble TNF-α concentrations were not significantly affected by tilmicosin.

Conclusion

Tilmicosin effectively controlled P haemolytica infection, induced neutrophil apoptosis, reduced pulmonary inflammation, and did not affect neutrophil infiltration or function.

Clinical Relevance

By inducing neutrophil apoptosis, tilmicosin prevents further amplification of inflammatory injury in P haemolytica-infected lungs. (Am J Vet Res 1998;59:765-771)

Free access
in American Journal of Veterinary Research

plasma and bronchoalveolar lavage fluid by high-performance liquid chromatography combined with electrospray ionization mass spectrometry . J Mass Spectrom 2007 ; 42 : 657 – 663 . 10.1111/j.1365-2885.2008.00989.x 22. Li XB Wu WX Su D , et

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in American Journal of Veterinary Research

. Effects of pentoxifylline on pulmonary function and results of cytologic examination of bronchoalveolar lavage fluid in horses with recurrent airway obstruction . Am J Vet Res 2002 ; 63 : 459 – 463 . 10.2460/ajvr.2002.63.459 24 Luke DR Rocci ML

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in American Journal of Veterinary Research

triamcinolone acetonide on pulmonary function and bronchoalveolar lavage cytologic features in horses with chronic obstructive pulmonary disease . Am J Vet Res 1993 ; 54 : 1310 – 1316 . 20. Cunningham FE Rogers S Fischer JH , et al The

Full access
in American Journal of Veterinary Research