Dr. Kellon: How long to Use Metformin

Kirsten Rasmussen

Hi Denise,

If you can "stay the course" with Metformin, try to continue, especially if you stop soaking hay due to cold temps.  Because you changed more than one thing at once (which is good, because you had to pull out all the stops to reduce that October insulin) it's impossible to say if the Metformin or the hay soaking are responsible for the big drop in insulin, but it's likely that both are helping and stopping one or the other (or both) will likely cause insulin to rise.  Even if the hay comes back with low sugar and starch, soaking it still helps to lower insulin.  The alfalfa pellets could be pushing up insulin, too, so I'd remove that, unless that's truly the only way you can get the Metformin in him.

The pain at temperature drops could be due to compromised circulation and/or elevated insulin and/or Dakota's thin soles, or a combination of all 3.  A change from soft to frozen ground can cause soreness in a barefoot horse with thin or unconditioned soles that does not have metabolic conditions. Testing insulin when he's sore will tell you if laminitis is also adding to the pain.  And warming him up with wool socks, fleece lined leg liners or shipping boots, and blanketing (so more heat is available to the extremities) will help with cold-related pain from reduced circulation.  Also, adding jiaogulan can really improve circulation to the hoof, but the drawback is that the trim needs to be in a good place because hooves will grow faster with improved circulation and that can cause mechanical issues in already compromised hooves.  If you haven't had your free hoof markups done, I strongly suggest requesting them, especially since you have recent radiographs:
You will need to take a full round of hoof photos exactly as shown in the above link, and upload them.

There are also boots that will accommodate studs for icy turnout, like Equine Fusions and Cavellos, while allowing enough room for pads and socks if you go up a size.  I've seen videos of a pony pulling a sleigh on a frozen pond that had no snow on it with studs in equine fusion boots, at a trot with no signs of slipping, so they DO work! 

Kirsten and Shaku (EMS + PPID) and Snickers (EMS) - 2019
Kitimat, BC, Canada
ECIR Group Moderator
Shaku's Case History
Shaku's Photo Album

Snickers' Case History
Snickers' Photo Album


Dr. Kellon,

I would really appreciate your input. Dakota's insulin was 114 on October 5, 2022 and the vet prescribed Metformin. His blood work three weeks after starting Metformin (on November 9, 2022) was as follows: 16 ACTH; 97 Glucose: 40 insulin. During this time, I also stopped feeding Empower Topline Balancer and he was fed soaked hay and alfalfa pellets with Platinum Performance (magnesium and chromium). He will not eat TC Timothy cubes with the Metformin (and the barn manager will not syringe and rinse). 

I am still waiting for the results of the hay analysis to balance his feed with the help of this group. We cannot soak his hay once it's well. below freezing.   

The vet merely reported his result and said to stay the course. ECIR files note that Metformin can lose effectiveness in some horses. Do you agree I should "stay the course" and continue with the Metformin?  If so, how long or when should I retest him? Clinically, he seemed much better until we had a significant drop in the temperature in WI (down to 9 degrees). He became quite sore. (I have ordered shipping boots but I can't use his cloud boots because his dry lot is icy.)

Does anyone have any feedback on Hygrain Feeds Zero? It's apparently 5.5% sugar/starch. I'm trying to find some feed that's acceptable but palatable to him. 

I apologize for not updating his CS. I need to reach out to one of those amazing moderators for help. 

Happy Thanksgiving to all on this site. Despite the ECIR issues, I have a lot to be grateful for-and I hope you too are thankful for your relationship with your horse (as frustrating as it can be at times!)

p.s. Dr. K, two of my three kids attended UPenn-it's the best!

Denise and Dakota (PPID + IR)