Feed Materials In Focus – Glucosamine is Safe for Cushings, EMS, Laminitic and Obese Horses


Glucosamine is Safe for Cushings, EMS, Laminitic and Obese Horses

The myth that certain horses should not be fed glucosamine due to its conversion to sugar is still circulating widely in some horse circles! 

This isn’t new knowledge and was actually reported over 100 years ago by James Colquhoun Irvine and Alexander Hynd in the Journal of the Chemical Society. So yes, Google “glucosamine conversion to glucose” or “glucosamine and insulin” and you’ll find some information. Interpretation is another thing and this is where the “popular” advice being given by some horse owners falls down. 

(1) Not all glucosamine is converted to sugars! In fact, only a small proportion is converted to glucose. Anderson et al. (2005) estimated that 1.7g of glucosamine taken orally in a 75kg person (equivalent to around 11g in a 500kg horse) would increase blood glucose by at most 0.06mmol/l or 1% i.e. barely measurable! 

(2) Even if ALL the glucosamine in a joint supplement at a recommended daily dose of 10g per day per 500kg was converted to glucose (and it won’t be), this would result in 10g of glucose – or 2 teaspoons! To put this in context, if we took typical hay with a water-soluble carbohydrate content (sugar content) of 150g/kg, then 10g of glucose would be equivalent to around 67g of hay – 1 or 2 mouthfuls of hay at the most! 

(3) Many of the studies suggesting a link between glucosamine and insulin dysregulation are either a) in isolated cells, b) use abnormally high doses, c) are flawed. As Pham et al. (2007) point out “glucosamine is widely used as a treatment for osteoarthritis, which is a condition associated with both obesity and type 2 diabetes mellitus [insulin insensitivity]”. And there is a major red flag. The condition for which people take glucosamine is a condition that is also associated with an increased risk of insulin insensitivity and obesity. To say glucosamine leads to insulin insensitivity or obesity is confusing an association with cause and effect! A common mistake. 

So is glucosamine safe for horses? Even laminitics? Obese horses? Cushings? Yes! 

Here are some quotes from the review by Anderson et al. (2005):

“Oral administration of large doses of glucosamine in animals has no documented effects on glucose metabolism.”

“Side effects were significantly less common with glucosamine than placebo or non-steroidal
anti-inflammatory drugs (NSAID).”

“Our critical evaluation indicates that glucosamine is safe under current conditions of use and does not affect glucose metabolism.”

A more recent review by Salazar et al. (2014) also concluded: “…evidence supporting diabetogenesis [i.e. insulin dysregulation] by glucosamine remains scarce in humans, and to date, this association should be considered only a theoretical possibility.” 


About Author

Dr David Marlin is a physiologist and biochemist who has worked in academia, research and professional sport. He has worked in the equestrian and veterinary world and in human sport, healthcare, medicine and exercise science. In 1989 David obtained his PhD from the UK’s leading sports university, Loughborough University following a four-year study on the responses of Thoroughbred racehorses to exercise and training, undertaken at the renowned Animal Health Trust in Newmarket. You can read David's full biography in the Our Website section.