metformin dosage

vicky monen


Can I ask what is the dosage for metformin for a 1000lb horse?

My vet gave me the following prescription and it sounds like alot to me.

my vet  "He’ll get 30 (500mg) tablets twice daily for 30 days. I put in 6 refills"

Under the metformin info under the files here, it suggests 
"The Metformin dose in horses is 30 mg/kg, twice daily, for a total of 60 mg/kg/day. After one week, retest insulin and glucose."

I just got his newest labs back and his Insulin is steadily increasing.  It is now at

ACTH Baseline Equine 8.53 pg/mL 2 - 35
Insulin Baseline Equine 91.26 uIU/ml 10 - 40

I obviously  have to add the metformin as his diet is very tight.  No grass, weighed low starch and sugar hay in ultra slow feed nets, rationed out 4 feedings through the day.  He has lost weight and definitely looks thinner than ever.  Hay is at 4.7% for the past few months now new hay is 5.2%. 

Prascend is at 2 mg per day at 1 xday.

I will add the metformin in hopes that it will help with the insulin.  Is this something he will need indefinitely, or until the insulin comes back down? He is super sensitive with any changes in diet, hay, medications, supplements, is there anything else to add with the metformin other than milk of magnesia? How much of milk of magnesia does he need?  He is also currently on omeprozole due to GI upset and diarrhea lately. 

Currently he shows no outward signs or symptoms that his pracend is not sufficient. 

Thank you for any suggestions. 
Vicky Monen and Samson

Aug 2015, Alpharetta Ga.

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