After explaining what crude ash in dog kibble covers, let's look at two minerals that deserve closer attention: calcium and phosphorus.
They are often associated with bones. That is correct, but incomplete. They participate in many bodily functions, and their importance cannot be summarized by a single figure or the idea that "adding more" will necessarily strengthen the skeleton.
As with proteins, carbohydrates, or fats, you must consider the complete formulation, the life stage, and the dog's actual needs.
🦴 What is calcium used for in dogs?
The majority of the body's calcium is stored in the bones and teeth, providing them with rigidity and structure. But this mineral is also involved in numerous daily functions.
In particular, it participates in:
- muscle contraction;
- the transmission of certain nerve signals;
- blood coagulation;
- the functioning of many cells and enzymes.
The body maintains the concentration of calcium in the blood within a narrow range. If the dietary intake or overall balance is not appropriate, it can mobilize the calcium present in the bones. This shows why calcium should not be viewed solely as a "building material."
⚙️ And what about phosphorus?
Phosphorus is also present in large quantities in the skeleton, where it works with calcium. It also has essential roles in energy metabolism: it is a component of molecules that allow cells to use and transfer energy.
It also contributes to the structure of cell membranes and participates in the body's acid-base balance.
In a diet, phosphorus can be provided by various ingredients, including animal raw materials, certain plants, and the mineral sources used to balance the recipe. Its origin and bioavailability can vary, which is one more reason not to judge a food based on a single total.
⚖️ Quantities and balance: two complementary pieces of information
Calcium and phosphorus are intimately linked. For a food to properly meet a dog's needs, you must look at the amounts of each, as well as their relationship.
A ratio that appears consistent is not enough if the total amounts are inadequate. Conversely, knowing only the calcium without the phosphorus does not allow you to understand the balance of the formula.
"Crude ash" provides information on the total mineral fraction, but it does not by itself indicate the quantity of calcium, phosphorus, sodium, or magnesium. This is why the details provided by the manufacturer are more useful when you want to compare the mineral content of two kibbles.
📐 What is the calcium/phosphorus (Ca/P) ratio?
The Ca/P ratio compares the amount of calcium to that of phosphorus in the same food.
The formula is simple:
Ca/P ratio = calcium ÷ phosphorus
For example, if a food contains 1.2% calcium and 1% phosphorus, its Ca/P ratio is 1.2.
This result describes a proportion; by itself, it does not provide a quality judgment or a universal recommendation. To interpret it, you need to know which dog the food is intended for, verify that both values are expressed on the same basis, and consider the actual quantities.
👉 A ratio therefore never replaces reading about the complete food.
🐶 Puppy and adult: needs that are not read in the same way
For a healthy adult, a complete food formulated for maintenance is designed to meet needs at the recommended ration. The priority is to choose a food adapted to the dog's profile and to distribute a quantity consistent with their activity and body condition.
For a puppy, the skeleton is building rapidly. Needs change with growth, and mineral intake must support this development without excess or imbalance.
Why future large dogs require special vigilance
Puppies destined to become large grow quickly and then carry a significant frame. Too rapid growth, an energy excess, or inappropriate mineral intake can disrupt skeletal development.
The right approach is not to look for the kibble with the lowest ash content, nor to add calcium "as a precaution." You must choose a complete food explicitly adapted to growth, and, where relevant, to the dog's expected adult size.
If you have any doubts about a puppy's growth, ration, or health status, the veterinarian remains the appropriate contact. This article does not replace individualized advice.
🚫 "A lot of calcium = stronger bones": why this is false
The skeleton is not strengthened by adding one single mineral without limit. It develops thanks to a combination: adapted energy intake, proteins, calcium, phosphorus, other nutrients, activity, genetics, and progressive growth.
An excess of calcium does not compensate for an inappropriate formula. In a puppy, it can instead contribute to imbalances in bone mineralization, especially if the formula or supplementation does not match their needs.
The shortcut "more calcium = better" is therefore as misleading as "more protein = better kibble": quantity needs a context.
🥣 Complete food or ration to be formulated: do not confuse the situations
A complete food correctly formulated for the dog's life stage is designed to provide the necessary nutrients when distributed according to its recommendations. Adding a calcium supplement without indication can unbalance this whole.
A homemade ration, a cooked ration, or a diet whose composition does not already cover all needs is not treated in the same way. It may require precise formulation and sometimes supplementation, ideally established with a veterinarian trained in animal nutrition.
In other words: the absence of a supplement is not an oversight in a complete food; supplementation is not automatically an improvement in an already balanced ration.
🔎 Where to find calcium and phosphorus if the label does not display them?
These two values are not always presented among the analytical constituents. Several avenues are useful:
- consult the detailed product sheet or the manufacturer's nutritional documentation;
- look for information intended for professionals or the complete nutritional table;
- contact the manufacturer directly and ask for the calcium and phosphorus levels, as well as the calculation base used;
- ask if the food is complete and for what life stage it is formulated.
An absent value does not equal zero. It remains unknown information. If the moisture level is different between two foods, you can also ask for data on dry matter in order to compare on a consistent basis.
🐾 No universal figure to look for
It is tempting to set a "good" Ca/P ratio or an ideal amount of calcium valid for all dogs. Yet, a growing puppy, a sedentary adult, a very active dog, or an animal with a specific medical situation cannot be compared in the same way.
The figures must be read in the context of the complete food, the ration actually consumed, and individual needs. For a pathology, atypical growth, or an unconventional diet, interpretation is done with an animal health professional.
🐺 The Sköll & Hati perspective
To concretely compare two foods, I proceed in this order:
1. I check the intended life stage.
I compare an adult food with another adult food, or two foods intended for growth. For a future large dog, I look for a formula that specifies its suitability for the growth in question.
2. I note calcium and phosphorus.
I note the two percentages, their unit, and their calculation base. If one of the values is missing, I don't guess it: I ask the manufacturer.
3. I calculate or check the Ca/P ratio.
I divide calcium by phosphorus. Example: 1.2% ÷ 1% = 1.2. I verify that both data points are expressed on the same basis before performing the calculation.
4. I do not stop at the ratio.
I also look at the quantities of calcium and phosphorus, the complete food, the energy provided by the ration, and other available mineral information.
5. I identify what needs to be asked.
Calcium, phosphorus, moisture, calculation base, suitability for the life stage, and, if necessary, information on other minerals. A precise answer from the manufacturer is more useful than an isolated ash total.
Key takeaways
- Calcium and phosphorus participate in the skeleton, but also in many essential bodily functions.
- You must examine their quantities and their Ca/P ratio, without forgetting the context of the complete food.
- A ratio alone does not make it possible to judge if the total quantities are appropriate.
- Growth, particularly in future large dogs, requires a truly adapted complete food.
- Adding calcium to a complete diet without necessity can unbalance a formula already built to cover needs.
- When values are not displayed, ask the manufacturer for them rather than relying solely on crude ash.