09/08/2024
If your arthritic horse is insulin-resistant, it's important to talk to your veterinarian about the risks and possible alternatives before agreeing to corticosteroid injections or topicals, especially triamcinolone.
A recent study by Hollowell et al. (2024) revealed that horses with higher baseline insulin levels experienced a greater insulin increase after receiving triamcinolone. While some horses showed only a slight rise, others saw a dramatic jump. This is critical because past research (De Laat et al., 2012) has shown that horses with insulin levels above 200 uU/ml are at high risk for developing laminitis.
For over 20 years, horse owners and experts have shared anecdotal stories about corticosteroid injections potentially triggering laminitis in horses. Back then, we didn’t fully understand what caused laminitis, let alone how these injections might play a role.
In 2001, a high-profile case in France sparked a lot of attention. A dressage horse was given corticosteroid injections in several joints before a major competition. Tragically, just days later, the horse developed laminitis and had to be euthanized. The owners sued the veterinarians, claiming they weren’t warned about the risk, and they won the case. This stirred controversy within the veterinary world, with many arguing that there wasn’t any scientific proof connecting corticosteroids to laminitis at the time.
For the next 10-15 years, various studies indicated that the risk of laminitis from corticosteroid injections was low. There was no significant link between the two, or so it seemed. What wasn’t clear yet was that laminitis is often triggered by hyperinsulinemia (high insulin levels).
One UK study examined thousands of corticosteroid injections in young racehorses (aged 2-5) and found that only one or two older horses possibly developed laminitis from the injections. The conclusion? The risk was considered very low, almost negligible.
However, these studies largely focused on young, fit horses—quite different from the older, arthritic horses many of us own. Older horses often develop conditions like PPID (Pituitary Pars Intermedia Dysfunction), and if they're arthritic and insulin-resistant, they may not move as much due to stiffness. This inactivity can lead to higher baseline insulin levels, so the conclusions of those studies on younger horses don’t necessarily apply to older ones dealing with arthritis and insulin resistance.
If your horse tolerates the injection well, their insulin levels may return to normal within a week. However, for those that experience a strong reaction, the damage to their hooves could already be done. Once a horse experiences laminitis to the point where they’re reluctant to walk, recovery becomes difficult. The lamina in the hooves may have already stretched, meaning it could take months before the horse can return to normal movement—if at all.
