Abnormally high calcium in the blood occurs much more commonly than low calcium. High blood calcium is most commonly associated with cancer. Less common causes of elevated calcium are chronic kidney failure, primary hyperparathyroidism which is over-function of the parathyroid gland, poisoning with certain types of rodent bait and bone disease. Low blood calcium may occur in dogs and cats just before giving birth or while they are nursing their young. This is called eclampsia and occurs more commonly in small breed dogs.
Eclampsia causes the animal to have rigid muscles which is called tetany.
Animals poisoned with antifreeze may have a very low blood calcium. Cholesterol Cholesterol is a form of fat. Cholesterol can be increased in the bloodstream for many reasons in dogs. It is much less common for cats to have increased cholesterol. Some of the diseases that cause elevated cholesterol are hypothyroidism, Cushing's disease, diabetes and kidney diseases that cause protein to be lost in the urine.