Last Updated on March 18, 2022 by Allison Price
Points of interest
Intestinal stones can form when certain elements like magnesium, ammonium and phosphate crystallize within the hindgut. The most common forms are spherical and tetrahedral.
Horses may have one or more intestinal stones. The average horse’s weight is between a few grams and several pounds.
High levels of protein (nitrogen), high magnesium intake, higher alkaline pH, and the presence a nidus (matrix that allows the stone to form) are some of the factors that can contribute to the formation intestinal stones.
Horses from the West Coast are more likely to get intestinal stones than horses from other parts of the United States.
Stones can increase in size and cause colic, intestinal blockage, or even death.
Alfalfa hay from the southwest U.S. adds a high level of calcium, magnesium, and nitrogen to the diet. The phosphorus content is low in alfalfa; however, the calcium buffers the pH in the hindgut.
Alfalfa is a significant contributor to the formation of intestinal stones. However, horses that are fed alfalfa have no problems with intestinal stones.
A diet that contains 100% alfalfa Hay can be replaced with some or all grass Hay to reduce intakes of nutrients, calcium and magnesium.
Horses with intestinal stone surgery should not be fed alfalfa pellets, cubes, or hay.
Research has shown that grains and grain-containing feeds can reduce the pH of the hindgut. There have been studies showing that apple cider vinegar can reduce the pH of the hindgut. However, no studies have shown that it will dissolve stones or prevent them from forming.
According to fieldwork, the pH of the water could also play a role in the alkalinity increase in the hindgut. Higher incidences of horses with intestinal stones have been found in California, where there are higher levels of pH (7.6 or higher).
There are several things you can do to reduce intestinal stone formation. It is not practical to eliminate the nidi from feeds.
You should reconsider alfalfa’s role as primary forage source if you have concerns about intestinal stones.
Magnesium intake should not be excessively increased by drinking hard water. Hard water can have a greater impact on magnesium intake because of the ability of the alfalfa plants to accumulate magnesium during growth.
Magnesium intake from wheat bran is not recommended. Bran is often fed in inadequate quantities to be considered a major factor.