Dr. Ellenor Kellon has done a lot of research on DSLD, she has yahoo group dedicated to it and is accessible if you have questions, need a supplement protocol, and/or want to participate in a study. It is not a new disease or a 'trendy' diagnosis but if I had to guess as to why the increase in the number of cases my guess would be attributed to the high iron levels in hay/pasture/feeds/water and the deficiency of copper/zinc. The copper and zinc levels in all the forage tests I have performed the past few years have been severely deficient and the iron content is extremely high. For anyone that doesn't know, iron, copper, zinc, and manganese all compete with each other for absorption. When balancing diets the ideal ratio of iron to copper is 4:1 (or less), the ratio for copper to zinc to manganese is 1:3:1.5 (manganese should be 1.5x the NRC guideline or 50% of the zinc amount but never higher than zinc). Copper is crucial to ligament/tendon health, as well as MANY other roles including how the thyroid/adrenal glands function. Metabolic disease is another red flag/contributing factor to DSLD. Here is some of Dr. Kellon's words on copper: Lysine is also the source of hydroxylysine, an amino acid which is only found in collagen. Studies have shown that dietary hydroxylysine is not used to make collagen; only hydroxylysine freshly synthesized from lysine. The enzyme responsible for the conversion of lysine to hydoxylysine is lysyl hydrolase. Another key enzyme, which creates the reinforcing cross-links in tendon and ligament structure, is lysyl oxidase. Copper is a required cofactor for both.3 Copper deficiency interferes with the activation of the two lysl enzymes.4 Copper is one of the most common deficiencies in equine diets and an important ingredient for tendon and ligament support. In addition to low dietary levels, bioavailability is compromised by high levels of iron. Iron competes with copper for absorption. Sulfates in water may cause problems because they bind copper and cause it to precipitate out. Many horse owners think they need to supplement iron to horses (think 'blood builders') but actually they are likely causing more harm than good - true anemia in the horse is EXTREMELY rare but relative anemia caused by deficiencies in supportive nutrients is more common. A simple blood test is not a true representation of the iron levels, the ferritin levels have to be measured and currently only Kansas State University can do this test. A feed tag or guaranteed analysis isn't going to give the true amount of iron a feed/supplement has, if it is included at all then the number printed is just what is 'added'. Unfortunately, iron is in most feed stuffs (for example, alfalfa and beet pulp are high) and some nutrient ingredients can be major contributors to the iron content in a product, such as: magnesium oxide, mono/di-calcium phosphate (which can be upwards of 20,000ppm iron), etc. The highest amount of copper that I have seen in 3+ years of hay testing for me and my clients/friends is 4mg per lb - an amount that won't even meet the NRC requirement (which is a LOW number) when fed at the amount that meets the DE requirement. The closest ratio between iron and copper that I've had on a test was 10:1 but that was an outlier - the majority were 30+:1. Just wanted to share a bit of this knowledge with this forum. Dr. Kellon offers some great nutrition courses that I strongly suggest all horse owners take. Your horses and your bank account will thank you for it. |