Comparison of efficacy and tolerability of isoflupredone and dexamethasone in the treatment of horses affected with recurrent airway obstruction ('heaves').
BACKGROUND
Corticosteroids are currently the most effective drugs for the control of 'heaves' in horses. However, there is limited information concerning the comparative efficacy and tolerability of the various corticosteroids when used for treatment.


OBJECTIVE
To compare the therapeutic and side effects of isoflupredone acetate to those of dexamethasone.


METHODS
A parallel design to compare the effects of 2 corticosteroids by evaluating lung function, serum cortisol and electrolyte concentrations, response to ACTH stimulation and haematology sequentially during a 14 day control period (no treatment), followed by 14 day treatment with either isoflupredone acetate (0.03 mg/kg i.m. s.i.d., n = 6) or dexamethasone (0.04 mg/kg i.v. s.i.d., n = 6) and 7 days of wash-out.


RESULTS
Both drugs were well tolerated clinically and resulted in a significant improvement in lung function that started on Day 3 and lasted for the treatment and wash-out periods. Blood cortisol levels were significantly decreased during the treatment period in both groups of horses, but a normal response to ACTH stimulation was preserved. Serum electrolytes concentration of horses receiving dexamethasone was not affected by the treatment, but horses treated with isoflupredone demonstrated a significant decrease in serum potassium level. Both treatments induced stress changes in haematology.


CONCLUSIONS
Isoflupredone is as effective as dexamethasone in the treatment of 'heaves'-affected horses but associated with hypokalaemia. Even if clinical signs of hypokalaemia were not observed, this is a side effect that deserves further investigation.
Picandet
V
V
Département des Sciences Cliniques, Faculté de Médecine Vétérinaire, Université de Montreal, CP 5000, Saint-Hyacinthe, Québec J2S7C6, Canada.
Léguillette
R
R
Lavoie
J P
JP
D000402:Airway Obstruction / Q000188:drug therapy / Q000662:veterinary*; D000818:Animals; D000893:Anti-Inflammatory Agents / Q000627:therapeutic use*; D018592:Cross-Over Studies; D003907:Dexamethasone / Q000009:adverse effects / Q000627:therapeutic use*; D005260:Female; D005477:Fluprednisolone / Q000009:adverse effects / Q000031:analogs & derivatives* / Q000627:therapeutic use*; D006734:Horse Diseases / Q000188:drug therapy*; D006736:Horses; D007273:Injections, Intramuscular / Q000662:veterinary; D007275:Injections, Intravenous / Q000662:veterinary; D008297:Male; D012129:Respiratory Function Tests / Q000662:veterinary; D016896:Treatment Outcome
D000893:Anti-Inflammatory Agents; C065592:isoflupredone acetate; D003907:Dexamethasone; D005477:Fluprednisolone