Intra-articular triamcinolone acetonide improves lung function in horses with severe asthma.

Abstract

Locally administered corticosteroids are commonly used to treat joint diseases in sport and racehorses. As they are also the most potent drugs for the treatment of equine asthma, we hypothesised that the intra-articular corticosteroids used to treat joint diseases also improve the lung function in horses with severe asthma, thus potentially delaying the diagnosis of this common lung condition. To compare the effects of intra-articular (IA) and intramuscular (IM) triamcinolone acetonide (TA) on lung function in horses with severe asthma. Randomised and controlled experiment on asthma-prone research animals. Horses with severe asthma in clinical exacerbation were given either 20mg of TA in both tarsocrural joints (n=5; 40mg/horse) or 40mg of TA intramuscularly (n=5). Lung function and TA serum concentrations were measured weekly for 35days. TA serum concentrations were also evaluated on day 3. The pulmonary resistance (RL ) and elastance (EL ) values decreased by day 7 in the IA group (P<0.0001 and P=0.003, respectively) and by day 14 in the IM group (P=0.002 and 0.03, respectively). Lung function was improved up to days 21 and 28 in the IA and IM groups, respectively, when compared with baseline. TA serum levels were below the quantification limit (100pg/ml) for 4 and 3 of the 5 horses in the IA and IM groups, respectively, on day7. The area under the curve for RL , EL and the serum concentrations of TA were similar in both groups. The response of horses with severe asthma might differ from that of high-performance horses with mild/moderate asthma. Intra-articular administration of TA improves lung function in horses with severe asthma, an effect that persists when TA serum concentration is below the quantification level that is employed as a threshold by the International Association of Racing Commissioners.