Big Head – Dietary Calcium Deficiency

Big Head a Dietary Calcium Deficiency

Big Head is a common problem in horses when they do not receive enough dietary calcium, and the horse mobilises calcium from the bone to keep blood calcium levels ?normal?. The calcium in the bone is replaced with fibrous tissue, causing the classic ?Big Head? and often shifting lameness. Big Head is common in horses from Sydney north to the Tropics.

Dietary calcium deficiency can be caused by

  1. Oxalate. Oxalate is found in sub-tropical grasses including buffel, setaria, kikuyu, green panic, para,  pangola, guinea, signal, and purple pigeon grass. The oxalate in the grass attaches to calcium in the horse?s gut and prevents it from being absorbed, thus causing a calcium deficiency.
  2. Phosphorus. Some feeds such a wheat bran contain too much phosphorus and too little calcium which can create the wrong Ca:P ratio and in some cases prevent calcium absorption. This also occurs in horse receiving high grain (high NSC) , low roughage diets fed to increase energy intake. This is termed Millers disease.
  3. Phytic acid which binds with calcium and prevents calcium absorption. Phytic acid is prevalent in feeds such as wheat bran.

Myths about Big Head

  1. Feeding some lucerne will prevent Big Head ? incorrect. Lucerne does not contain enough calcium to prevent Bighead. It will however help balance the Ca:P  where horses are eating a small amount of grain or grain by-products.
  2. Injecting Vitamin D  will prevent or cure Big Head 2. ?  incorrect. While the absorption of calcium relies on vitamin D being present, Big Head is caused by a calcium deficiency, so no matter how much vitamin D you give it won?t help unless the horse also has dietary calcium available to absorb.

Preventing Big Head.

  1. Simply feed enough available calcium to overpower the oxalate, phytate or phosphorous? ability to bind the calcium in your horses gut. You can supplement with  limestone or dicalcium phosphate, but check that the calcium is bio available, and that you don?t overfeed calcium to young and performance horses and cause a Ca:P imbalance.
  2. Alternatively select bio available  calcium fortified feeds such a GoStance, which is a scientifically formulated feed to provide the correct balance of nutrients and energy. GoStance also provides balanced NSC (non structural carbohydrate) designed for active horses to avoid the NSC related metabolic disorders