Question:  My 9yo Welsh cross mare is PSSM 1 diagnosed by mane DNA testing. She is more on the overweight side. I've changed her feed already from triple crown complete to a ration balancer instead. I tried adding Cocosoya oil to her feed initially but she doesn't like oil at all. Currently her diet is:
1 lb Legends CarbCare Balancer Pellets
1lb Omegatin pellets (I added this in an effort to get more fat since she won't eat oil)
4ml KER Nano-E
2 oz Quiessence (we initially thought she was insulin resistant but her ACTH came back normal)
~10Lbs orchard grass hay soaked

-I'm concerned about adding too much fat because I've heard it can cause them to be insulin resistant. Should I use L-Carnitine or drop the fat and use ALCAR or neither?
-I've heard chromium (in the Quiessence) is bad for PSSM horses. Should I change to a magnesium only supplement?
-Also, I had considered using hay pellets or beet pulp for increased fiber or with oil if she would eat it. Which would be better? Alfalfa pellets, timothy pellets or alfalfa/timothy pellets. I was looking at the Standlee brand of these three. I feel like alfalfa hay makes her very hyper, but I wasn't sure if timothy pellets would be too high in NSC.

Dr. Kellon: With a horse that is already overweight and a genetic tendency (Welsh) to develop IR, you have nothing to lose by trying ALCar first.  Most people start to see response within 2 days to 2 weeks.  Give her 1 g/100 lbs body weight twice daily for 10 days, then once daily.
CarbCare is a bit too high in sugar + starch (14%)  for some; Omegatin the same.  You may have to go to a concentrated vitamin/mineral supplement and plain beet pulp as a carrier.  Rinsed then soaked beet pulp is by far the safest.


Continue your E but use plain magnesium oxide (e.g., 8 to 10 g/day of magnesium, because chromium will increase glucose intake by the muscle.


If you let us know where your hay was grown I can suggest an appropriate mineral supplement for your area or you could analyze your hay for a more precise fit.

Question: Thank you so much for your recommendations! This is certainly a journey that I wasn't expecting to be on! If I start the ALCAR, should I drop the omegatin since it is high in fat? If I understand correctly, the ALCAR is for the low/no fat added diets.

She has trouble sweating in the summer, but did well last year on OneAC. I don't know if anhydrosis has any relation to PSSM or would affect what her diet needs to be.

I live in the piedmont of NC and the barn owner gets all her hay from this area. I have thought of getting it tested but she gets from multiple people.....30 or 40 bales here and 30 or 40 bales there so the hay is never very consistent unfortunately! The hay is usually orchard/Timothy or orchard/fescue. It used to be mostly orchard grass. I feel like the quality of the hay is probably not very good. Feeding beet pulp would also be a problem because the barn owner says it is too much trouble and too messy. I'm on the waiting list at another boarding barn for these reasons.

This mare was supposed to be my easy and simple horse! I greatly appreciate your input!

Dr. Kellon: If you start ALCar, I would drop the Omegatin both for high fat and potentially too much starch/sugar.  The only added fat should be what's in 4 to 6 ounces of flax or a flax based omega3:omega6 4:1 supplement.

Anhidrosis is not related to PSSM. Mechanism remains poorly understood but you do want to make sure calcium and chloride needs are being met.


Many NC hays have a problem with low calcium/high phosphorus which complicates making any suggestions about how much magnesium to use or which vitamin/mineral supplement.  I would suggest asking if your hays always come from the same geographical area and if so go ahead and have an analysis done.  It may well vary a bit but is far better than blind guessing.