Notes from Finding safe forages for laminitics video presented by Dr Nerida Richards of FeedXL, September 2020.

The majority of laminitis cases are caused by insulin [endocrinopathic laminitis].  It is insulin that damages the hoof.  

​Taste tempters that you might add to the feed  - either mixed in or sprinkled on the top - include: 
dry or fresh herbs e.g. mint, fenugreek
fruit and herb teas
grated carrot or apple
crushed sugar free mints/polos
crushed strong smelling horse treats
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Q.  My horse won't eat his mineral supplement.

Here are some suggestions for getting a horse to eat a mineral supplement:

• Start by giving a very small amount in a large amount of carrier (unmolassed chaff/sugar beet), and if that is accepted, gradually increase it up to the recommended amount - a small amount of minerals is better than nothing.
• Mix the minerals into dry feed before wetting it, to make sure they are well distributed and don't form clumps of yucky tasting minerals when you dampen the feed.
• Try mixing the minerals into something else first, such as linseed or salt, before adding to the feed.
• Try adding a bit of strong flavouring, such as peppermint. Or try using a bit of Stevia - as far as we have been able to check, a small amount of Stevia should be safe for EMS horses.
• Try top dressing the bucket with something that the horse will eat - when horses turn up their noses at their minerals, we mix the minerals well into the feeds, then sprinkle a bit more HiFi molasses free on top of the feed before giving it, the smell of this seems to help disguise the minerals.
• If your horse really won't eat from a bucket, try sprinkling the minerals onto damp hay, ideally mixed with the daily salt.

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Q:  A friend with type 2 diabetes commented that biotin helps balance her insulin levels. Is there any info on this for horses?

A:  A study of published research suggests that there is currently insufficient evidence that biotin supplementation is beneficial for humans with type 2 diabetes (T2DM) (see below).  Where research has suggested a benefit of biotin supplementation in humans with T2DM, 
Biotin deficiency in humans is very rare, and it is thought that average daily intakes of biotin from the diet exceed likely requirements.  It isn't currently known if humans are able to absorb and use biotin produced by gut bacteria.

See Biotin - Linus Pauling Institute.

The Laminitis Site is not aware of any research in horses that has looked at the effect of supplemental biotin on blood insulin or glucose levels.  However, some points to consider:

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​The US National Library of Medicine's page on biotin suggests that there is insufficient evidence to rate the effectiveness (of biotin) for diabetes (in humans):
"Diabetes. Biotin alone doesn’t seem to affect blood sugar levels in people with type 2 diabetes. However, there is some evidence that a combination of biotin and chromium (Diachrome, Nutrition 21) might lower blood sugar in people with diabetes, whose diabetes is poorly controlled by prescription medicines. Other early evidence shows that the same combination reduces ratios of total cholesterol levels to “good” high-density lipoprotein (HDL) cholesterol, “bad” low-density lipoprotein (LDL) cholesterol to HDL cholesterol, and non-HDL to HDL cholesterol in people with type 2 diabetes."

In humans, this 1993 paper suggested that serum biotin was low in people with type 2 diabetes and that biotin supplementation reduced hyperglycaemia:
Masaru MAEBASHI, Yoshio MAKINO, Yuji FURUKAWA, Kosaku OHINATA, Shuichi KIMURA, Takao SATO
Therapeutic Evaluation of the Effect of Biotin on Hyperglycemia in Patients with Non-Insulin Dependent Diabetes Mellitus
Journal of Clinical Biochemistry and Nutrition Vol. 14 (1993) No. 3 P 21

and this 2007 paper found that blood glucose levels lowered in obese patients with T2DM given a combination of chromium and biotin:
Am J Med Sci. 2007 Mar;333(3):145-53.
Chromium picolinate and biotin combination reduces atherogenic index of plasma in patients with type 2 diabetes mellitus: a placebo-controlled, double-blinded, randomized clinical trial.
Geohas J1, Daly A, Juturu V, Finch M, Komorowski JR.

However, chromium alone has been suggested to lower hyperglycaemia in diabetic patients, so the positive effects suggested by the above paper by Geohas et al. may not have been due to the biotin:
J Clin Pharm Ther. 2014 Jun;39(3):292-306. doi: 10.1111/jcpt.12147 
Systematic review and meta-analysis of the efficacy and safety of chromium supplementation in diabetes
Suksomboon N1, Poolsup N, Yuwanakorn A

and this paper from 2004 found no effect on blood glucose or insulin levels after 28 days of biotin supplementation (in fact, insignificant increases in blood glucose and insulin were seen in the biotin supplemented diabetic and non-diabetic people compared to the placebo groups - see Table 2)
Am J Clin Nutr. 2004 Feb;79(2):238-43
Effects of biotin on pyruvate carboxylase, acetyl-CoA carboxylase, propionyl-CoA carboxylase, and markers for glucose and lipid homeostasis in type 2 diabetic patients and nondiabetic subjects
Báez-Saldaña A, Zendejas-Ruiz I, Revilla-Monsalve C, Islas-Andrade S, Cárdenas A, Rojas-Ochoa A, Vilches A, Fernandez-Mejia C

Q:  My horse has been prescribed Metformin but I am having trouble getting her to eat the tablets.  Any suggestions?

A:  One owner found that crushing Metformin tablets in a coffee grinder then mixing them with a small amount of stevia encouraged her horse to eat the tablets when mixed into her normal feed.  Sugar free peppermints could perhaps also be used.  

Metformin will dissolve in water.  Some owners dissolve it then syringe it into the mouth, either just in water or mixed with apple sauce, sugar free cordial or flavoured yogurt.  Try to keep sugar low!

You might discuss with your vet whether your horse needs to have Metformin.  Metformin is called "exercise in a tablet" by some vets, and may be prescribed if a horse cannot exercise due to laminitis, or if insulin levels are very high.  However, research by David Rendle et al. suggested that any benefit of Metformin may be questionable when  horses are on a low sugar/starch diet (as they should be if they have EMS or a history of laminitis) - see Metformin.  

Here are some tips for encouraging fussy horses to eat mineral supplements in their feed - these may be helpful for disguising medicines too:

• Start by giving a very small amount in a large amount of carrier (e.g. unmolassed chaff/sugar beet), and if that is accepted, gradually increase it up to the recommended amount - a small amount of minerals is better than nothing (however this may not be the case for medicines - check with your vet).
• Keep the carrier (e.g. unmolassed chaff/sugar beet) to mineral ratio low - it seems logical that a horse is more likely to notice 40 g of minerals in 100 g of chaff than in 400 g of chaff.
• Make sure the horse likes everything in the rest of the feed - do a taste test of individual ingredients if necessary.
• Mix the minerals into dry feed before wetting it, to make sure they are well distributed and don't form clumps of yucky tasting minerals when you dampen the feed.  
• Try mixing the minerals into something else, preferably nice-tasting and/or with a strong flavour, first, such as linseed, salt, dried herbs (e.g. mint) or stevia, before adding to the feed. Other possibilities include grated carrot or apple, sugar free apple sauce, low sugar/starch nuts made into a mash with warm water. 
• Try top dressing the bucket with something that the horse will eat - mix the minerals well into the feed, then sprinkle a bit of nice tasting/smelling feed on top of the mixed feed. TLS uses HiFi Molasses Free - this smells of mint and fenugreek and most horses seem to find it appetizing.  Or try grating some carrot or apple on top of the feed - a small amount does not add much sugar to the feed - see Who said "stop the carrots"?
• Try mixing the feed using a fruit tea such as raspberry, mint, cinnamon, apple - find out what your horse likes first.
• Give him plenty of time to eat his bucket feed, ideally with nothing else available for a couple of hours.  Or feed when he is hungry, e.g. first thing in the morning.
• You could try sprinkling the minerals onto damp hay, ideally mixed with the daily salt (again, this may not be suitable for medicines when the full dose needs to be given).

A few more tips:

• Make sure you and your horse remain calm - try to make taking the medicine a fun event, not a stressful one.
• Try introducing a bit of competition - feeding other horses nearby may encourage your horse to eat up. 

More information:
Equine Metabolic Syndrome and insulin dysregulation
Management Strategies for EMS/Insulin Resistance
Diet

Significantly, according to an example given by Andy Durham in his 2008 paper The effect of metformin ... (see below), in which one horse had a fasting resting insulin at the start of the research (presumably without clinical laminitis) of 32.8 miu/l, and a fasting resting insulin after 220 days of Metformin treatment and a recurrence of clinical laminitis of 377.5 miu/l.

Factors that may affect insulin levels include:
pain, illness, PPID, excitement, stress, recent exercise, recent eating/length of fasting, obesity, genetics, fitness, time of day, time of year, reproductive status, age and environmental temperature.

Equine Vet J. 2008 Jul;40(5):493-500
The effect of metformin on measurements of insulin sensitivity and beta cell response in 18 horses and ponies with insulin resistance.
Durham AE, Rendle DI, Newton JE.

Yes.  

Research by Pleasant et al. found that horses that were overweight had higher insulin and leptin levels than horses that were the correct weight.  Obese horses had higher triglyceride levels.  They concluded that keeping horses at a Body Condition Score less than 7 might be important for decreasing the risk of pasture-associated laminitis.

Pleasant RS, Suagee JK, Thatcher CD, Elvinger F, Geor RJ
Adiposity, plasma insulin, leptin, lipids, and oxidative stress in mature light breed horses
J Vet Intern Med. 2013 May-Jun;27(3):576-82