When was the last time you looked at your horse's feed bag label? What about their supplement ingredients?
It may be time to look at the ingredients in all that you feed to ensure that you are not accidentally over-supplementing your horse.
As an example:
Say you feed your horse Blue Seal's Sentinel Performance LS feed and the recommended feeding ration is 4.5lbs/1,000lbs body weight (see analysis below). Your horse is also on MedVet Pharmaceuticals 6-Way Pellets (see analysis below). Without knowing it, you may be over-supplementing your horse on one or more vitamins and minerals. By understanding this, you could potentially feed a different supplement (that may be less expensive because it has less overlapping ingredients) or you could switch to a different feed or feed ration balancer.
Analysis for Sentinel Performance LS:
MedVet Pharmaceuticals 6-Way
If you look closely at ingredients for both the feed and the supplement, you will see that both include Lysine, Methionine, Copper, Manganese, Selenium, Zinc, Vitamin A, Vitamin E, Biotin, Omega-3, and Omega-6 Fatty Acids.
After looking at the recommended daily intake values for a horse that is in moderate use, you can see if you are overfeeding one ingredient. In this case, all of the ingredients that are in both the feed and the supplement exceed the daily recommended amount.
While some ingredients are water soluble and can be removed from the body if they are in excess, some ingredients can be toxic if fed in excess.
Mild Vitamin A toxicity can lead to poor skin and coat condition. A more severe toxicity can lead to depression, bone deformities, and neurological dysfunction, in addition to death.
Vitamin D toxicity can lead to depression, decreased appetite, weight loss, and calcium deposits on the lungs, heart, and other organs.
Vitamin K is high amounts is rare, but can lead to acute renal failure.
Magnesium (Mg) toxicity can lead to a decreased function of the metabolic and digestive systems.
Potassium (K) excess is general harmless in most horses, unless your horse has hyperkalemic periodic paralysis (HYPP). If your horse has HYPP, increased potassium can lead to decreased muscle function.
Selenium (Se) levels are very important to understand as the ideal vs. toxic levels have a very small margin. If your horse receives too much selenium, there could be heart or liver damage, cracks in the hooves, degeneration of joints, muscles, and bones, and in severe cases, death.
Zinc (Zn) toxicosis is generally rare, unless your horse grazes near a metal refinery. If your horse has excess zinc levels, they may show signs of limb stiffness, lameness, growth plate enlargement in foals, and bony limb deformities.
If you horse is on additional supplements, even if they are primarily joint, gastro, etc., they may be receiving even more vitamins and minerals than they need. Therefore, it is vital that every supplement that is added to your horse's diet should be thoroughly researched and questioned prior to its addition. As always, you should consult your veterinarian before changing, adding, or removing any supplement or feed. Keep in mind the daily recommended values to ensure that you are not hurting your horse's system.