Calcium supplements often come in chewable (., chocolate-flavored) or tablet formulation in human medicine, and are readily found in households. When dogs ingest these supplements in large amounts, it can result in electrolyte changes (., transiently elevated calcium blood levels) or even chocolate poisoning in dogs. (Cats, by the way, generally do not ingest enough of these supplements to result in poisoning due to their discriminating palate.) Calcium supplements often also contain large amounts of Vitamin D3 and Vitamin K, which can also result in toxicity. While calcium is generally poorly absorbed from the gastrointestinal tract, the addition of Vitamin D3 increases the risk of toxicity.
not going to be home when the next doseage is due, what can I
This is tough. If you can, give the dosage earlier rather than later. If it is easier to give the dosage that day every 8 hours instead of every 12, divide the dosage into thirds and give. And if you give the dosage really early, you might want to give an extra dosage when you get home. If you have a responsible neighbor or friend that could stop in and give your dog the medication, that would be perfect. Another thing you could try (but I would try this out before you needed to use it) would be to get one of the automatic cat feeders. You could set the timer to release the food (along with the medication) at a specified time. Just make sure that your dog will take the pills this way and not just eat the food - leaving the pills behind.