Intra-articular corticosteroid injections are widely used in equine practice for the management of 
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joint pain and lameness. Despite their clinical benefits, concerns persist regarding the potential for corticosteroid-induced laminitis, particularly following reports of laminitis developing after joint injections. While many joints are injected safely every year, adverse metabolic consequences appear to be relatively uncommon, raising questions about whether specific corticosteroid formulations, dosages, or patient factors influence risk.
One proposed mechanism for corticosteroid-associated laminitis involves systemic metabolic effects following intra-articular administration. Corticosteroids are known to interact with the hypothalamic-pituitary-adrenal (HPA) axis and may interfere with glucose and insulin metabolism. Disruption of these pathways, particularly the development of hyperinsulinemia, is strongly associated with laminitis. However, not all corticosteroids appear to exert identical metabolic effects, and differences between formulations may be clinically relevant.
To address these concerns, Allen E. Page and colleagues conducted a controlled study at the Maxwell H. Gluck Equine Research Center, Department of Veterinary Science, Martin-Gatton College of Agriculture, Food and Environment, University of Kentucky. The objective of the study was to examine the metabolic effects of intra-articular methylprednisolone acetate (MPA) when administered into multiple low-motion joints.
The study population consisted of six 3-year-old mixed-breed geldings from the university’s research herd. All horses were screened approximately five weeks before the investigation and were confirmed to be free of pituitary pars intermedia dysfunction (PPID) and insulin dysregulation. This ensured that any observed metabolic effects could be attributed to treatment rather than pre-existing endocrine disease.
Each horse was randomly assigned to receive either intra-articular MPA or an equivalent volume of saline. MPA was administered bilaterally into the distal intertarsal and tarsometatarsal joints, with a dose of 20 mg per joint for a total of 80 mg. Serial blood samples were collected to measure resting adrenocorticotropic hormone (ACTH), cortisol, insulin, and glucose concentrations. In addition, repeated low-dose oral sugar tests were performed to assess post-challenge insulin and glucose responses. After a six-week washout period, treatments were crossed over and the protocol was repeated.
The results demonstrated that intra-articular treatment with a total dose of 80 mg of MPA caused significant suppression of the HPA axis. Specifically, resting ACTH and cortisol concentrations were significantly decreased between four and twelve hours following MPA injection. This finding confirms that even intra-articular administration of corticosteroids can produce measurable systemic endocrine effects.
Importantly, however, no significant changes were observed in resting insulin or glucose concentrations. Furthermore, insulin and glucose responses to oral sugar testing at 2, 7, and 14 days post-treatment were not affected by MPA administration. These findings contrast with previous reports involving other intra-articular corticosteroids, which have demonstrated post-injection hyperinsulinemia.
The authors conclude that, in metabolically normal horses, an intra-articular dose of 80 mg of MPA does not appear to induce clinically significant disturbances in insulin or glucose regulation. This observation may help explain the reported practitioner sentiment that MPA carries a lower risk for corticosteroid-induced laminitis compared with other formulations.
Nevertheless, the study’s findings should be interpreted cautiously. The horses involved were young, healthy, and free of known endocrine disease. Additional research is needed to determine whether similar results would be observed in insulin-dysregulated or laminitis-prone horses. Until such data are available, intra-articular MPA should not be assumed to be universally safe in higher-risk populations, despite its apparently favourable metabolic profile in healthy individuals.
For more details, see:
Page, A. E., McPeek, J. L., Carattini, S., McGreevy, E., & Adam, E. (2025).
Intra-articular methylprednisolone acetate does not induce hyperinsulinemia or hyperglycemia in metabolically normal horses.
Journal of the American Veterinary Medical Association (2025).
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