Calcium is a mineral usually acquired from diet that is important for heart muscle and bone health. Supplements are available over the counter and by prescription for people for conditions like osteoporosis, but should only be used under the supervision of a veterinarian in animal patients with calcium deficiencies, such as in patients like female dogs suffering from eclampsia. Calcium powder supplements are even available as dietary additions for reptiles. While small doses may only cause mild side effects like vomiting and diarrhea, higher doses can cause some pretty serious side effects such as weakness, tremors, kidney failure, even death. Best to grab the bottle and call the vet or our 24/7 Help Line for assistance.