Re: GOOD news / BAD news / differentials for hyperinsulinemia

Kerry Isherwood

Hi Lavinia!
Thanks for your reply.  All excellent info.  I have asked Dr. Kellon to consult privately about my gelding's case but I have a few specific questions for you, too, to further my education.  I've included the bits of your reply for reference (my questions are preceded by  >>>>> ):


---In EquineCushings@..., <shilohmom@...> wrote :

Hi Kerry,

...Uncontrolled PPID will, over time, bring on a secondary IR even in the most non-IR breeds but that is not going to be the case in a 7yo.

>>>>> Just to be sure, I'm going to send an ACTH to Cornell, even though my gelding is very young for PPID.  That being said, he has always been an extremely anxious, easily stressed horse (I mean, sometimes he's unrideable and even unmanageable on the ground b/c he's so upset for no discernable reason--and I'm pretty brave, not afraid to handle or get on anything).  So, my question is, can a stressed horse raise his endogenous cortisol to the point of creating a "PPID scenario"?  And therefore IR?  Or, can chronic stress raise insulin to his levels (40's)? 

...Although the "typical" IR horse is portrayed as overweight, with fat pads in telltale locations, and always easy keepers this is not the whole story. Many (most?) mildly IR horses do well when working and while they are young. As they age, or their workload decreases, or some other stressor comes into play, they can suddenly show up as IR when in reality they have always been that way but were managing because of the exercise and youth and no tested them at that time.

>>>>> Good point.  My gelding is very fit (can go for hours on rocky hilly NE trails) so prob not exhibiting the typical fat pads.  Furthermore, this guy maintains perfect body condition on ab lib moderate quality grass hay (no grain) even with hard work, so I would say he is an easy keeper.  Even though he doesn't appear to have any body fat, I've added on a leptin at Cornell just to see if it comes up with anything interesting. 

...The grass paddock is likely contributing to the rise in the insulin, esp if the the grass has been frosted or under cold stress as it will store extra sugar to help deal with the cold temps (like plant anti-freeze). The insulin in the 20's already said he was mildly IR at that time. A truly non-IR horse has insulin below 10.

>>>>> Yes, the pattern def fits that when he moved onto a grassier paddock his insulin jumped significantly.  He was not unduly stressed by the move (it was on the same farm) and even seems happier in the new pasture, so I don't think stress contributed to that 47 insulin as much as the grass did.  Previously he's been living in a drylot just b/c my mare was, so that also fits the pattern of why this IR is emerging now, when he moved to my trainer's farm and was on grass for the first time. I'm going to have to muzzle him until we get significant grass dormancy and/or snow-cover. 

...Have you had him tested for Lyme? That can drive high insulin secondary to the infection. It can also make a horse ultra sensitive to stimulus.

>>>>> I had in the past (years ago) but that is a good point; I'll add that at Cornell.

...Magnesium deficiencies in the diet are also a possibility but no way to know without testing the hay.

>>>>> Wouldn't it be poss to determine his Mag level by bloodwork?  I had him on Quiessence (full dose) for the quieting effect(!) and his first chemistry showed his Mag level was very high (3.8mEq/L;  normal 1.1-2.3) so I d/c the Qui and his recheck chemistry showed Mag in normal levels (1.8mEq/L). 

...Iron overload is another possible driving force behind IR. Most horses get too much iron from their diet to begin with, then supplements and grains add more. To test, you need to send a sample to Kansas State University and get serum iron, ferritin and TIBC. KSU is the only lab that can test for equine ferritin.

>>>> Another good point, and I'm going to submit samples of both of my IR horses to KSU asap.  Thanks for the tip. 

...Recommendation is to get him on a mineral balanced diet. Farrier's formula is a decent product but quite high in iron. Vit E in gelcap form with oil in it is the most cost effective and most readily absorbed, ground flax to provide omega 3's and salt are basic for all horses. All other minerals will depend on what is already in excess/deficiency in the diet. Many electrolyte products are high in sugar. Salt is the most necessary electrolyte and the one that is generally lacking in a horse's diet. Unless the horse is sweating heavily for several hours daily, there is no need to use targeted electrolyte supplements.

>>>>> I'm confused a little about the Farrier's Formula being high in iron?  There is no iron listed in its guaranteed analysis (I use a maint dose of the orig formula).  Will you elaborate on your source, please?

>>>>> This gelding is a "sweater" like I've never seen -- we always thought it was just nerves, but regardless of why, I always give him electrolytes after he works, year-round.  His first chemistry showed a low chloride so I recently added electrolytes in the morn handful/meal as well.  He also has had two episodes of "thumps" (luckily we didn't have to do any emergent treatment either time, but scared me enough to always give him electrolytes after working).  However, I was using an electrolyte with dextrose, so I have now switched to a suger-free version.

....What type of "issues under tack" prompted you to have him tested?

>>>>>Well, this is a long story that I'll try to keep brief & succinct.  I adopted him 4 years ago from New Holland (a low-end "meat auction" notorious here in the NE as a major supplier of cheap horses for slaughter).  He was three at the time, and went thru auction as "unbroken" but it was soon very apparent that someone had severely abused this horse under tack -- he almost flipped over the first time we tried a bridle on and has so many learned evasions for such a young horse that he was literally unrideable for many months.  There was discussion early on from my trainer that he must have an old injury that was causing his evasions so we did every possible diagnostic on him (full bloodwork, lyme neg, robaxin & bute trials (did not respond), several chiro visits from THE best (Dr. Allen Schoen, who coulnd't find anything wrong on three separate visits) etc etc etc.  So we rested him for several months.  Then I did months and months of groundwork, then ponying him off my mare, then trail riding (we're talking all over span of 2 years) and I got him to the point where he was actually happy under tack, BUT, he would still have enough completely crazy days where you couldn't do anything with him, his behavior was so frantic & upset. Those days didn't make any sense; there was no pattern or reason for him to be Dr. Jekyll/Mr. Hyde like that -- so after watching him go under tack one day (a bad day) my vet said that we could try a gabapentin trial, on a hunch, b/c he looked to her (my vet) that he would "one day be a head-shaker".  Lo & behold, he was greatly improved on low-dose gabapentin and has been on it since Apr 2014 (1200mg, once/day, morning).  Life was great, he was working well (best he's ever been) so I decided to move him to my trainer's barn for the winter for use of her indoor so we could keep him in training.  This gelding has never been able to live stalled (he gets so upset being confined that he actually colics) so he went into rough board at my trainer's in a big grassy paddock Oct 1st.  He didn't settle well, but knowing him, I didn't expect him to (!).  A couple weeks there my gelding was suddenly completely out of control again -- even on the ground, behaivor we had long ago put to rest and buried.  I discovered the person in charge of feeding was giving my guy several quarts of sweet feed (some kind of senior feed) even though I had explicitly told her not to give more than a handful.  I decided to run full bloodwork to make sure his kidneys/liver were handling the 1200mg gabapentin ok, b/c I didn't know what else to do except increase the dose, and b/c he was so incredibly and abruptly out of control while getting grain I decided to tack on an insulin/glucose -- his reaction wasn't just "up" or "high" behavior on the grain---I mean he was so frantic and out of his mind he was dangerous to deal with even on the ground.  That's when I found an insulin in the 20s (glucose was low, but tube had sat around awhile before spinning, so I wasn't worried).  He had been off the grain for several days before that blood draw.  His whole chemistry was very abnormal (like, I didn't even believe it) so a week later I reran it and sent the insulin to Cornell...and it was now 47.8, reflecting the move to the grassier paddock in between the two chemistries.  Interestingly, the first chemistry--along with many other abnormalities-- showed a CK of 1,143 U/L (normal 100--300) even though my gelding had been off work for several days before blood draw.  And his AST was quite low (38U/L, normal 180-380).  So .... rhabdomyolysis or not?  So that brings case up to date pretty much. 

...Try to remember to breathe - keeps you from passing out and allows you to think more clearly. Wine and chocolate are also great for putting things into perspective :)

>>>>> Agreed, sister!  Nothing like a nip o' Bailey's by the fireside to cap off a stressful day!!  :)))

Thanks!  LMK your thoughts.  I so appreciate your input!!  I'll set up a CH for this horse too. 

Kerry in NY
Sept 2014

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