How much calcium is too much in dog foods? In 2007, the Association of American Feed Control Officials (AAFCO) convened a panel of experts from academia and industry to, in part, make recommendations for revision of the AAFCO Dog and Cat Food Nutrient Profiles. These profiles, which were last revised in 1995, serve as one means by which the nutritional adequacy of dog and cat foods can be substantiated in the US.
Now, seven years later, the recommendations of the panel have yet to be put into place. There is agreement as to recommended levels of nutrients with one major exception; that is, the maximum calcium concentration that should be allowed in dog foods for different life stages and breeds.
The charge to the expert panel when it was formed was to consider the newly released (at the time) publication Nutrient Requirements of Dogs and Cats (2006) by the National Research Council (NRC), as well as other scientific information available since the last revision of the AAFCO Profiles. The safe upper limit as recommended by NRC for dog foods intended for growth is 1.8% dry matter (at 4000 kcal ME/kg).
There is no differentiation as to breed of dog in the NRC tables; i.e., it applies to all dog foods intended for puppies. However, in looking at the supportive text, NRC notes, "Thus, excess dietary calcium has been shown to cause clinically recognizable bone abnormalities in growing dogs, but these effects appear restricted to puppies of large breeds."
The AAFCO expert panel did make a breed-based distinction in its tables when they were first released, though. It recommended a maximum 1.8% Ca DM for foods intended for large/giant-breed growth, but the status quo (i.e., 2.5% Ca DM, as in the current AAFCO Dog Food Nutrient Profiles) for smaller breeds of puppies and for adult dogs (maintenance and gestation/lactation) regardless of breed.
When first released, the recommendations of the expert panel were not without controversy. For example, the panel also recommended that the minimum calcium and phosphorus levels in large/giant-breed puppy foods be reduced compared to that required for other puppies. However, the American College of Veterinary Nutrition (ACVN) disagreed with the conclusion of the panel in this matter, an opinion with which the US Food and Drug Administration (FDA) concurred.
Ultimately, the AAFCO Pet Food Committee sided with ACVN's and FDA's viewpoint, and rejected the panel's recommendation for a breed-based difference in minimum calcium and phosphorus concentrations. At no time did any group argue against the recommendation for a differentiation in maximum calcium levels for growth based on breed, though.
The modification of the recommendations for revisions to the AAFCO Profiles to require the same minimum calcium and phosphorus levels in all "growth and reproduction" dog foods were made after the January 2013 AAFCO meeting. However, for some unclear reason, the document was also amended so that the maximum calcium was set at 1.8% Ca DM for all dog foods, without distinction for breed or life stage. This discrepancy apparently was overlooked until brought up at the August 2013 meeting.
I was not present, but as I understand it, the resolution of the Pet Food Committee at the meeting was to compromise as follows: 2.5% Ca for all adult maintenance dog foods, but 1.8% Ca DM for all dog foods intended for growth and reproduction (aka, "all life stages"). In other words, no differentiation in maximum levels based on breed of dog.
The AAFCO Profiles as amended did pass the AAFCO Model Bill & Regulations Committee at the January 2014 meeting. Normally, that would mean it would go to the full membership for a vote at the next meeting, which if passed would go on to be published in the next edition of the AAFCO Official Publication. However, it is my understanding that the Pet Food Committee will ask to hold on this final step while it reconsiders this matter. Clearly, unlike the debate regarding the minimum calcium and phosphorus levels, there was a gap in due deliberation with respect to maximum calcium levels. In my opinion, this should not have happened.
Regardless, I personally think the maximum 1.8% Ca DM for all "all life stages" dog foods is prudent, and frankly, much easier to regulate. The trouble is, the AAFCO Profiles are complicated enough to verify, and having a breed differentiation in the mix just muddies up the whole thing. Most dog foods bearing an "all life stages" statement on their labels do not indicate breed or size of dog. So, theoretically, such a food could be fed to large/giant-breed puppies to their possible detriment.
If the original panel recommendation is to become part of the AAFCO Profiles, there would need to be adequate measures in place to prevent incorrect feeding from happening. For example, an "all life stages" food would have to be clearly designated for "small and medium breeds," or there would have to be some other qualification to expressly exclude large- and giant-breed puppies. Otherwise, it would have to comply with the 1.8% maximum Ca DM in order to meet the AAFCO Profiles. Implementation and verification of those restrictions are bound to be confusing for both regulators and the petfood industry.
However it turns out, I hope AAFCO can get the revised Profiles in the Official Publication as soon as possible. Who knows, maybe NRC is set to revisit its recommendations in the near future, so this whole process within AAFCO might have to begin again soon!