Intra-articular (IA) administration of corticosteroids is performed routinely in equine practice. The lung function of severe asthmatic horses has recently been shown to be improved by IA triamcinolone acetonide (TA). We therefore hypothesised that IA methylprednisolone acetate (MPA), another commonly used corticosteroids, would also decrease the airway obstruction in severe asthmatic horses.
To compare the effects of intra-articular (IA) and intramuscular (IM) methylprednisolone acetate (MPA) administration on lung function and serum cortisol levels in horses with severe asthma.
Randomised and controlled experiments on severe asthmatic research animals.
Severe asthmatic horses in exacerbation were administered 200 mg of MPA either intramuscularly (n = 6) or via intra-articular injections in the tarsocrural joints (n = 6; 100 mg/joint). Serum cortisol concentration and pulmonary function was measured for 8 days.
A significant decrease in pulmonary resistance in the IA group (p = 0.003, mean diff 1.14) on day 1 in comparison with baseline was observed. A significant decrease from baseline was also observed on serum cortisol values in the IA group 6 hours after injection (p=0.001, mean diff 44.5), and at day 1 (p=0.003, mean diff 45.1).
Joint health was not evaluated in the current study and the physiological response of the severe asthmatic horses might deviate from that of the milder forms of asthma.
MPA IA administration improves the lung function of severe asthmatic horses. However, this effect was mild and of a short duration.

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