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  • Author or Editor: Joyce E. Hakala x
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Abstract

Objective—To evaluate clinical response, pulmonary function, and adrenal gland response to incremental doses of beclomethasone dipropionate in horses with recurrent airway obstruction.

Design—Crossover trial.

Animals—8 horses with recurrent airway obstruction.

Procedure—Horses randomly assigned to 4 groups were treated twice daily via aerosol administration of placebo or 500, 1,000, or 1,500 µg of beclomethasone dipropionate in a crossover design with a 10-day minimum washout period. Subjective assessment of airway obstruction, serum cortisol concentration, and maximum change in pleural pressure during tidal breathing (ΔPplmax) were determined daily prior to morning drug administration, and ΔPplmax was reevaluated 15 minutes after morning drug administration. Pulmonary resistance and dynamic compliance were determined at baseline and approximately 12 hours after the final treatment.

Results—An immediate treatment effect was not identified. Within 24 hours, ΔPplmax and airway obstruction were lower in horses receiving beclomethasone. Onset and magnitude of response was similar among the 3 beclomethasone dose regimens. Pulmonary resistance was improved only after administration of all 3 doses of beclomethasone, whereas dynamic compliance was improved after administration of 1,000 µg and 1,500 µg of beclomethasone. Reduction in serum cortisol concentration occurred with all 3 beclomethasone dose regimens; however, the magnitude of adrenal gland suppression was greater in horses receiving 1,000 or 1,500 µg of beclomethasone.

Conclusions and Clinical Relevance—Low-dose (500 µg) beclomethasone administration caused similar improvement in pulmonary function, compared with high-dose beclomethasone (1,000 and 1,500 µg), with the exception of dynamic compliance, and caused less suppression of endogenous cortisol production. (J Am Vet Med Assoc 2000;217:359–364)

Full access
in Journal of the American Veterinary Medical Association

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

Abstract

Objective

To determine the dose of aerosolized albuterol sulfate required to cause bronchodilation in horses with recurrent airway obstruction (RAO) and duration of this effect.

Animals

19 horses with RAO (10 in experiment 1; 9 in experiment 2).

Procedure

Horses were moved from pasture to stables, and airway obstruction was induced. Pulmonary function was measured in 10 horses before and 5, 10, and 30 minutes after administration of vehicle or 120, 240, 360, or 720 µg of the drug. Nine horses received vehicle or 360 or 720 µg of albuterol, and pulmonary function was measured at baseline and 5 minutes and 1, 2, 3, 4, 5, 6, and 7 hours later. Horses were evaluated for adverse drug effects.

Results

360 µg of albuterol was required to cause significant bronchodilatation; 720 µg did not enhance bronchodilatation or increase duration of action. Depending on which pulmonary function parameter was evaluated, bronchodilatation achieved by use of albuterol lasted between 30 minutes and 1 hour. Because there was a significant vehicle effect, the combined effect of vehicle and drug lasted up to 3 hours. Adverse effects were not observed.

Conclusions

Aerosolized albuterol, 360 or 720 µg, is a safe and effective bronchodilator in horses with RAO. Onset of action is rapid (5 minutes), and effects last from 30 minutes to 3 hours.

Clinical Relevance

Aerosolized albuterol is useful for treatment of bronchospasm in horses with RAO. (Am J Vet Res 1999;60:689–693)

Free access
in American Journal of Veterinary Research

Abstract

Objective

To determine whether pulmonary distribution of aerosolized technetium Tc 99m pentetate is improved after inhalation of a single dose of albuterol sulfate in horses susceptible to recurrent airway obstruction (heaves).

Animals

6 horses with heaves and 4 horses with normal respiratory tract function.

Procedure

Images were obtained during ventilation of horses at baseline (maximal change in pleural pressure during tidal breathing [ΔPplmax] > 15 cm H2O) and after aerosolized albuterol sulfate (360 µg) administration, with a 24-hour washout period between experiments. The ΔPplmax was determined prior to the baseline scan, prior to albuterol sulfate administration, and 5 minutes after albuterol sulfate administration. Images were assessed by visual inspection (semiquantitative scoring system) and histogram analysis.

Results

Images obtained from horses with heaves had nonuniform pulmonary distribution of radionuclide characterized by poor penetration in peripheral lung fields and excess deposition in large airways. Histogram analysis of images of the caudal portions of the lungs revealed nonuniform radionuclide deposition in horses with heaves and uniform radionuclide deposition in control horses.

Conclusion

Administration of a single dose of aerosolized albuterol sulfate improved pulmonary distribution of aerosolized radiolabeled pentetate suspension in horses with heaves but did not alter pulmonary distribution in clinically normal horses.

Clinical Relevance

Precedent bronchodilator administration may improve pulmonary distribution of aerosolized, surface-active anti-inflammatory preparations. (Am J Vet Res 1999;60:764–769)

Free access
in American Journal of Veterinary Research

Abstract

Objective

To determine alteration in adrenocortical function in horses with recurrent airway obstruction (heaves) after aerosol and parenteral administration of beclomethasone dipropionate and dexamethasone, respectively.

Animals

6 horses with inducible and reversible heaves.

Procedure

Episodes of heaves were induced by exposure to moldy hay and straw for 7 days (natural challenge). Horses then underwent treatment (aerosolized beclomethasone, parenterally administered dexamethasone, and aerosolized propellant) for 7 days. Horses remained in the mold-contaminated environment for 7 days after discontinuation of drugs. Adrenocortical function was determined by serial evaluation of Cortisol concentration in serum obtained on days 0, 7, 9, 12, 14, 16, 19, and 21. Adrenocorticotropic hormone stimulation testing was performed in 4 horses/treatment group on days 0, 7, 14, and 21.

Results

Endogenous Cortisol production was suppressed in beclomethasone- and dexamethasone-treated horses within 2 days of treatment but recovered to values similar to those in propellant-treated horses approximately 2 and 4 days after discontinuation of drugs. Serum Cortisol concentration in propellant-treated horses gradually decreased during the study and was significantly lower than baseline on days 14, 16, 19, and 21. Mean increase in serum Cortisol concentration in response to ACTH stimulation testing after beclomethasone and dexamethasone administration did not differ significantly from the response observed in propellant-treated horses.

Conclusions

Aerosol and parenteral administration of beclomethasone and dexamethasone, respectively, suppressed adrenocortical function; however, endogenous cortisol production resumed approximately 2 and 4 days after discontinuation of drugs. Responsiveness to ACTH stimulation testing was not affected by the 7-day treatment period. (Am J Vet Res 1998;59:1044–1047)

Free access
in American Journal of Veterinary Research

Abstract

Objective

To determine changes in clinical signs of disease and response to pulmonary function testing in horses with recurrent airway obstruction (heaves) after aerosol and parenteral administration of beclomethasone dipropionate and dexamethasone, respectively.

Animals

6 horses with inducible and reversible heaves.

Procedure

Episodes of heaves were induced by exposure (challenge) to moldy hay and straw for 7 days. Horses were assigned to treatment groups (aerosolized beclomethasone dipropionate, parenterally administered dexamethasone, aerosolized propellant [control]), and respiratory frequency and subjective assessment of respiratory effort were determined twice daily. Maximal change in pleural pressure (ΔPplmax), pulmonary resistance (RL), and dynamic compliance (Cdyn) was determined on days 0, 7, 10, 14, and 21.

Results

The RL and ΔPplmax were increased, and Cdyn was decreased in all horses in response to natural challenge. Beclomethasone reduced RL on day 10, reduced ΔPplmax on days 14 and 21 and increased Cdyn on day 14. Dexamethasone reduced RL and ΔPplmax on days 10, 14, and 21 and increased Cdyn on days 10 and 14. Respiratory effort (subjective assessment) improved after 2 and 3 days of beclomethasone and dexamethasone administration but rebounded to pretreatment values 1 and 3 days after discontinuation of drugs.

Conclusions

Pulmonary function testing responses and clinical signs of airway obstruction were improved by administration of beclomethasone. The magnitude of response to aerosolized beclomethasone generally was less marked than the response to parenterally administered dexamethasone. Higher or more frequent dosing of aerosolized beclomethasone may be necessary to achieve the anti-inflammatory response to parenterally administered dexamethasone. (Am J Vet Res 1998;59:1039–1043)

Free access
in American Journal of Veterinary Research