The typical horse with moderate recurrent airway obstruction may have 30% to 70% neutrophils in the bronchoalveolar lavage fluid, resting airway resistance that is elevated twice to three times normal, and visible signs of increased breathing effort. This horse would show a 30% to 50% reduction in airway resistance after receiving 450 meg of albuterol via metered-dose inhaler. This horse would have recommendations for radical environmental modifications and would be treated with a four-week (weeks 1-4) decreasing course of systemic corticosteroids (e.g., prednisolone), with inhaled therapy beginning in the second to third week of treatment (week 3).
- • salmeterol 210 μg (10 puffs) twice daily
- • fluticasone 2200 μg (10 puffs) twice daily
- • salmeterol 210 μg (10 puffs) once daily
- • fluticasone 2200 μg (10 puffs) once daily
- • Lung function recheck at end of 4 weeks; if good response:
- salmeterol 210 μg once daily
fluticasone 2200 μg every other day
This client should contact the veterinarians monthly, and the horse should have twice-yearly to yearly lung function rechecks to fine-tune inhaled drug therapy and keep the disease in remission. During periods of remission, lung function tests are aimed at measuring baseline airway resistance and airway reactivity. Heightened airway reactivity suggests the need for intensive long-term treatment.
The horse with inflammatory airway disease is usually younger (2-7 years), although older horses can manifest inflammatory airway disease without heaves. Typical findings include declining performance, cough, and persistent mucoid discharge visible mostly upon endoscopy. Exercise intolerance commonly is observed in horses with inflammatory airway disease, and in these cases, lower airway inflammation is present. Bronchoalveolar lavage reveals elevated neutrophils, mast cells, or eosinophils, and increased airway reactivity to histamine is also present.
Examples of Treatments
Weeks 1 and 2
- • fluticasone 2200 μg (10 puffs) twice daily or beclomethasone hydrofluoroalkane-134a, 1000 nig (5 puffs)
- • albuterol 450 μg (5 puffs) before steroid inhaler and at least 30 minutes before exercise
- • fluticasone 2200 μg (10 puffs) once daily or beclomethasone HFA, 1000 mg (5 puffs)
- • albuterol 450 μg as needed, not to exceed 3 times/week
- • fluticasone 2200 μg once daily or beclomethasone HFA, 1000 mg (5 puffs)
- • albuterol should no longer be necessary
- • Rechecking at the end of the week to determine further course of treatment