Equine Veterinary Journal Early View February 2016
By Heather Ferguson
Does oral prednisolone treatment increase the incidence of acute laminitis?
Jordan V.J, Ireland J.L and Rendle D.I
There is concern that the use of oral prednisolone in horses and ponies potentially increases the risk of laminitis. This retrospective case-control study set out to determine whether there was evidence to support this. Clinical records from ambulatory practice over a period of 13 years were analysed. Horses that had received treatment with oral prednisolone (total 416) were compared against two time-matched controls (total 814) that had not received prednisolone treatment and had been seen by the same veterinary surgeon before and after the horse which had been given prednisolone. The median age in both groups was 13 years and there was no significant difference in breed or sex distribution between the groups. Overall laminitis incidence rate and laminitis rate during prednisolone treatment were calculated and where more than one episode of laminitis occurred in the same horse, only the first was included.
There was no statistically significant difference between prednisolone treated and non-treated groups in overall incidence of laminitis or incidence during the treatment period. In total, there were 62 cases of laminitis, giving an overall incidence of laminitis of 3.19 per 100 horse years at risk. Horses had been treated with prednisolone for a variety of disease conditions and there was no association between reason for treatment and risk of laminitis. In the non-prednisolone treated group, 32 episodes of laminitis occurred over the study period, giving an incidence of 3.46 per 100 horse years at risk.
In the prednisolone treated group, 16 laminitis cases occurred, giving an incidence of 2.6 per 100 horse years at risk. Seven of these laminitis episodes occurred during the prednisolone treatment period, giving an incidence of 20.84 per 100 horse years at risk during the period prednisolone was being given. The time at which the laminitic episode occurred in relation to prednisolone treatment was variable (median 34 days after commencement of treatment), with 3 cases developing laminitis more than one month after the end of prednisolone treatment.
Of the 16 cases of laminitis in the prednisolone group, 6 were investigated for underlying endocrine disease and all 6 were confirmed to have either pituitary pars intermedia dysfunction (PPID) or equine metabolic syndrome (EMS). There was no significant difference in the prevalance of these endocrine conditions between the treated and non-treated groups, but across both groups horses with PPID or EMS had a significantly higher incidence of laminitis compared with horses without endocrine disease although within the prednisolone group, laminitis rates during treatment were not different in those with and without endocrine disorders. Previous history of laminitis and increasing age were associated with increased risk of laminitis. Of the 15 horses euthanased because of laminitis during the study, 3 were from the prednisolone group and 12 from the control group, with no association between prednisolone treatment and mortality due to laminitis.
Oral prednisolone treatment did not increase the risk of laminitis in this study.