If you want to be all scientific-y about the Calcium:Phosphorus in the foods you feed your dog, you can research the Calcium and Phosphorus content of specific foods at the following pages:
- USDA National Nutrient Database pdf file on Calcium content of foods (sorted alphabetically)
- USDA National Nutrient Database pdf file on Phosphorus content of foods (sorted alphabetically)
- This page has a Calcium:Phosphorus chart of various foods
- And here is an explanation of how to calculate elemental Calcium
Calcium supplementation to the home cooked canine diet is an important consideration when diet alone does not provide the proper Calcium:Phosphorus - which is usually the case. If we look at a sample dinner of 1 cup of cooked broccoli, 1 cup of cooked long grain white rice, and 1 cooked chicken thigh (bones removed), we get a Calcium to Phosphorus ratio of approximately 1:3.2 which is not at all balanced for dogs. (Remember, we are aiming for more Calcium than Phosphorus.) Meat is high in Phosphorus and low in Calcium and so an all meat diet is not balanced for dogs either.
At the other end of the spectrum, excess Calcium in the diet may be dangerous for some dogs. Large breed puppies for example are at increased risk for skeletal abnormalities when fed diets high in Calcium. And pregnant bitches who consume too much Calcium may experience eclampsia - a life threatening veterinary emergency. But for a normal adult dog, excess Calcium is probably not a concern.
So, in short, if you're cooking for your dog, you probably need to add a Calcium supplement. (Geez, couldn't I have just said that to begin with?)
By the numbers:
Minimum Daily Requirements for Calcium (Canine)
per National Research Council (NRC) 1985 Guidelines:
(Note: The 2006 NRC guidelines don't have these same numbers by dog's body weight and are calculated differently. I'm just using the 1985 numbers as a reference.)
Growth: 320 mg/kg body weight
Adult: 119 mg/kg body weight
You can do your own math for your dog's weight using this customizable table for converting pounds to kg but here are a few samples:
20# dog needs 1079mg Ca per day (roughly half tsp eggshell powder per day)
50# dog needs 2699mg Ca per day (roughly 1 heaping tsp eggshell powder per day)
60# dog needs 3213mg Ca per day (roughly 1 and 1/2 heaping tsp eggshell powder per day)
70# dog needs 3778mg Ca per day (roughly 2 tsp eggshell powder per day)
Personal note: Sorry to have been absent recently but I've been down with a cold and so my online time has been limited. I need more MEs!