All commercial pet foods (this doesn't apply to prescription or supplemental diets) are required to meet the nutrient profiles for one or both of only two categories: Growth (puppy/kitten or lactating females) or Adult Maintenance.For a dog or cat food to be allowed to claim it is formulated for "All Life Stages", it must meet the requirements for BOTH Growth and Adult Maintenance standards. But to use terms like "senior" or "formulated for large breed adults", the pet food maker is only required to meet the requirements for Adult Maintenance - nothing more. Terms like "less calories" and "reduced calories" mean only that the product has fewer calories than another product; otherwise it is only required to meet the standards for Adult Maintenance.

One of the most important differences between Growth & Adult Maintenance nutrient profile standards is their protein levels. For both dogs and cats, Growth formulas are required to have significantly higher minimum protein levels than Adult Maintenance formulas.

Because protein is the most expensive ingredient in pet food (and since feed control officials only require higher levels of protein in Growth formulas) some pet food companies save money by formulating lower protein diets and branding them as “Senior”, "Large Breed", "Low-Cal" etc. It is just a marketing spin on the fact that the nutrient levels in the food may be much lower.

Since dogs and cats thrive on high levels of quality protein in their diet throughout their lives (there's no truth in the old notion that healthy senior pets need less protein), we prefer pet food from companies making the higher protein "All Life Stages" formulas or, when they do make a Senior, Large Breed or Low-Cal food, they do so without lowering the levels of quality, meat-based protein.

It's always a good idea to discuss your pet’s dietary requirements with a holistic veterinarian who understands the importance of species-appropriate nutrition and the individual needs of your pet but, unless your veterinarian directs you to curtail protein to help with a diagnosed medical condition, there is no reason to feed a lower protein diet to your pet - no matter his age, breed or size.