What are calcium supplements?
Calcium is a major structural component of bones and teeth, and is an essential dietary mineral. Various forms of calcium are available for supplementation. Calcium bound to lactate, citrate, ascorbate, and other organic acids appears to be more easily and completely absorbed than inorganic calcium supplements, such as calcium carbonate.
Veterinary practitioners who advise feeding your pet as close to a natural diet as possible often recommend bone meal as a calcium source, in part because it contains an ideal ratio of calcium to phosphorus. However, studies in humans do not demonstrate any significantly different net impact on calcium and phosphorus metabolism between bone meal and calcium carbonate supplements. In addition, bone meal supplements can contain undesirable heavy metal contaminants such as lead.
Coral calcium is often advocated as a supplement by its manufacturers, but research to support any benefits from coral calcium over other sources of calcium is lacking.
"Coral calcium harvesting has adverse consequences on marine ecosystems..."
Coral calcium supplements are often prohibitively expensive and their harvesting has adverse consequences on marine ecosystems such as coral reefs; they are not recommended.
Why recommend administration of calcium supplements to my pet?
Calcium supplements are often added to home-prepared diets to ensure proper calcium balance. Meat is naturally deficient in calcium, as are most vegetables and grains. Without adequate calcium, painful bone deformities may arise. Some vegetables, such as broccoli, kale, and collard greens contain high levels of calcium in a bioavailable form, and should only be included in a diet if specifically directed. Although spinach is high in calcium, it does contain high levels of oxalates, which may predispose some animals to develop urinary stones (see our handout on Home Prepared Diets for further information).
"Additional calcium should NEVER be added to a puppy's or kitten's diet without first consulting a veterinarian who is knowledgeable in animal nutrition."
Pets that are consuming a commercially prepared diet do not require extra calcium, since calcium is already added to the food. Calcium requirements may be higher for female animals in the last trimester of pregnancy, or for a female that is nursing a large litter of kittens or puppies. These requirements can be met by feeding a good quality commercial food intended for growth and development. Signs of calcium deficiency in nursing animals include weakness, tremors, and seizures. Additional calcium should NEVER be added to a puppy's or kitten's diet without first consulting a veterinarian who is knowledgeable in animal nutrition.
How much experience is there with the use of calcium supplements in pets?
Supplemental calcium has been used extensively to treat calcium deficiency. Intravenous calcium is commonly used to treat seizures resulting from calcium deficiency. This condition is most commonly seen in dogs whose blood calcium levels fall shortly before or after giving birth to a litter of puppies.
What species of animals are being treated regularly with calcium supplements?
All animal species, including humans, require adequate calcium. Problems due to inadequate calcium intake are most common in dogs, cats, and many captive reptiles. Calcium deficiency in reptiles most often arise from inadequate or inappropriate use of vitamin D. Deficiency in dogs and cats most often occurs in pets that are being fed an imbalanced homemade diet.
How much research has been conducted on this supplement?
Widespread research demonstrates the benefits of supplementation in pets with calcium deficiency. Calcium is a required mineral in the diets of dogs and cats; calcium deficiency results in debilitating bone diseases and may even be fatal if not treated properly. Prevention is clearly preferred by feeding a diet that includes the necessary amount of calcium.
How safe are calcium supplements?
They are safe when used correctly. However, normal pets not needing supplementation can have problems if given too much calcium.
"Normal pets not needing supplementation can have problems if given too much calcium."
Any time pets are given excessive amounts of supplements, including calcium, the balance between nutrients is disturbed. For example, calcium competes with other minerals such as magnesium for absorption in the intestine. If excessive amounts of calcium are provided, other minerals such as magnesium and zinc may become depleted. In addition, excessive calcium supplementation has been linked to the development of canine hip dysplasia. Avoid giving excess calcium to large rapidly growing puppies (see our separate handout on calcium supplementation in puppies).
In dogs prone to development of bladder stones, it is possible that excessive calcium supplementation may increase the risk of calcium oxalate stone development in the urinary tract. Several studies in humans suggest that the use of calcium citrate supplements inhibits the formation of calcium oxalate stones, since citric acid will help keep the calcium in soluble form in the urine. Increased absorption of dietary aluminum has been noted in humans with the use of calcium citrate supplements, but it is not known whether this poses any health risks to dogs and cats.
Where do I get calcium supplements and do I need a prescription?
Pet owners are cautioned against buying supplements without knowledge of the manufacturer, as supplements are not highly regulated and some supplements may not contain the labeled amount of calcium. Some calcium supplements contain Vitamin D to enhance their absorption, and these are usually appropriate for use in cats and dogs. Your veterinarian may have preferred brands or formulations of calcium supplements that he or she will recommend. A prescription is not needed for calcium supplements.