11/20/2024
CUSHINGS (AKA PPID), INSULIN RESISTANCE (IR), AND EQUINE METABOLIC SYNDROME (EMS)
Cushings is defined as a benign pituitary adenoma which simply means it’s a benign tumor. It affects hormonal output which can cause certain outward ‘symptoms’ such as a long hair coat that doesn’t shed properly. It has been said that any horse who lives long enough will develop it at some point. That said, there are much younger horses who have been diagnosed. It is NOT a death sentence. Properly managed, horses can live long, healthy lives. Not managing it and allowing it to get too far out of control CAN result in other undesirable issues such as insulin resistance, laminitis, and even DSLD.
Cushings is managed with a medication called pergolide, available as brand name Prascend, or as a compounded drug. It is NOT a one and done dosing. Horses need to be monitored through regular bloodwork to make sure they are on the correct dose. As time goes on, the odds are high the dose will need to be increased.
Cushings is not managed through diet but is frequently confused or lumped with EMS – Equine Metabolic Syndrome, also referred to as insulin resistance or IR – which is controlled with diet and exercise. Two different conditions. A horse can have Cushings and not be IR. They can be IR and not have Cushings. And they can have both.
Insulin resistance is a metabolic condition and should not be thought of as a disease. It isn’t. It was actually a self regulating survival mechanism for horses before man domesticated them. We just made it worse.
All bodily systems run on glucose (i.e., sugar) which the horse gets from everything they eat. Glucose requires insulin to actually get into the cells and start providing energy. An IR horse has a problem with that transportation system. The pancreas, which produces insulin, has to produce more and more insulin to get that glucose into a cell. This increase in insulin can cause its own problems.
IR horses are managed by managing diet and exercise (exercise only if they are not laminitic). Again, not a death sentence unless everything gets out of control. Key to this diet is lowering sugar (i.e., glucose). And everything has sugar. All hays have sugar but some are lower than others. IMPORTANT: THERE IS NO WAY TO DETERMINE THE LEVEL OF SUGAR AND STARCH IN ANY GIVEN HAY UNLESS YOU SEND IT TO A LAB FOR TESTING. That’s not always feasible for people who are not buying a ton or two of hay at a time. There are generalizations that certain hays are *generally* lower in sugar and starch than others, but again, no guarantee without testing. One proven way to lower the sugar in any hay is to soak it, drain it, and feed it. That will lower the sugar content by roughly 30%. If you have a horse tipping on the verge of laminitis, and your vet advises you to reduce sugar, soaking hay is the fastest way to do it. You may have to do other diet tweaks, but soaking is a good place to start. A horse who is insulin resistant does not need any excess sugar in their diet.
Bagged feeds are another issue. Manufacturers will label a particular feed as low sugar and starch. In reality, it most likely isn’t. It WILL be lower than the other feeds in their line, but the odds are high it won’t be low enough.
So how do Cushings and IR sometimes come together? An elevated hormone level indicative of Cushings causes an increase in cortisol which counteracts insulin and leads to IR. High insulin can lead to laminitis which is how some owners first discover that their horse is IR and/or Cushings. (If your horse is already laminitic, exercise won’t be possible but diet will be even more key.)
And what of EMS? A more all encompassing term that takes in blood levels and symptoms or clinical findings, but elevated insulin is still at the root.
The takeaway here is that Cushings is managed with medication and IR is managed with diet and exercise in a non laminitic horse. And the takeaway from THAT is careful, attentive management. There are no magic bullets.
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