Despite attempts to educate clients about managing their horses’ environments for optimal airway quality, situations arise that compromise the airways and lead to equine asthma.
One method of treatment relies on corticosteroids to minimize lung inflammation. However, systemic treatment with glucocorticoids, especially dexamethasone, suppresses cortisol to result in unwanted side effects. Inhaled fluticasone has been used in an attempt to side-step systemic treatment, yet when inhaled, this drug is not as effective in controlling asthma as systemically administered dexamethasone. While nebulized dexamethasone doesn’t elicit cortisol suppression, it also doesn’t improve lung function.
A new inhaled medication—ciclesonide—has recently been approved by the FDA as a nasal spray (Aservo EquiHaler by Boehringer Ingelheim).
A study presented at 2019 AAEP Convention described crossover, placebo-controlled, blinded, randomized studies using different doses of inhaled ciclesonide over a three-year period [Lavoie, J.P.; Bullone, M.; Rodrigues, N.; et al. Effect of different doses of inhaled ciclesonide on lung function, clinical signs related to airflow limitation and serum cortisol levels in horses with experimentally induced mild to severe airway obstruction. Equine Veterinary Journal 2019, vol. 51, issue 6, pp. 779-786; DOI: 10.1111/evj.13093].
All horses in the three studies—eight horses in each study—received all the dosage treatments but in a different order. The soft mist inhaler used produces 65-80% of particles with a size ≤5 um. Effects of inhaled ciclesonide for two weeks of treatment were compared to placebo and/or dexamethasone (0.066 mg/kg per os) treatments. Lung function and clinical scores were evaluated before treatment and after Days 7 and 14 of treatment. Serum cortisol was measured pre-treatment and at 3, 5, 7, 10, and 14 days of treatment and on Days 3 and 7 after treatment stopped.
- Study 1 – Horses were treated with 450, 900, or 1800 ug, or dexamethasone BID.
- Study 2 – Horses were treated with 1688 ug, or 2700 ug, or dexamethasone BID using two different nozzle delivery systems for ciclesonide dosing.
- Study 3 – Horses were treated with placebo, ciclesonide 2700 ug twice a day, ciclesonide 3713 ug once a day in the morning, or ciclesonide once daily in the evening, all using the same nozzle delivery system.
Conclusions of the study were encouraging for use of ciclesonide to reverse airway obstruction in equine asthma.
- Results are similar to oral dexamethasone when ciclesonide is given at the higher doses.
- Maximum clinical effects are achieved at 2700 ug twice a day, and these favorable effects were seen by Day 7.
- There were no significant changes in CBC or serum chemistries with ciclesonide, whereas oral dexamethasone suppressed cortisol from Day 3 of treatment up to Day 3 after treatment. Placebo treatment did not alter clinical parameters.
- Evening treatment appeared to be better than morning treatment.
- Ciclesonide is not associated with cortisol suppression and is the only steroid with this quality.