Magnesium and potassium, along with sodium and calcium, are examples of electrolytes that are present in the blood. Electrolytes help trigger and regulate electrical impulses in the heart and low levels of magnesium and potassium can lead to an electrolyte imbalance, which can contribute to arrhythmia.
Passing hard stools is usually as a result of constipation or the infrequent movement of the bowels. Most healthy people have at least three bowel movements per week, according to MedlinePlus. If you are unable to have a bowel movement or are having difficulty passing stool, contact your doctor.
Hard stools in humans are usually the result of either insufficient water intake or of the body's absorbing excessive liquid out of the stool. Rarely do dogs have problems with constipation or hard stools, because their gut is pretty short. Dogs generally don't have enough gut length for too much water to be absorbed. Loose stools are a much more frequent problem in dogs than hard stools. Stools form in the colon, and that is where most of the water is absorbed from dietary waste material, in order to form a solid stool.