With so many brands of pet food for pet owners to choose from, commercial dog food makers pursue customers using crafted marketing strategies. By capitalizing on widespread perceptions, or misconceptions, owners have about pet nutritional needs, these companies have created a myriad of life-stage, lifestyle, and breed specific products to capture the market share.
This proliferation of “specially formulated” foods only further solidifies a more widespread belief in the need for such products. Some of these nutritional strategies are supported by scientific data confirming their value. Most are not. The notion that geriatric pets need special nutrition is a case in point. Older pets have the same needs as younger animals, unless they develop specific diseases.
Protein in Senior Pet Foods
Commercial food strategies for protein in senior diets have traditionally been either providing less protein or more protein. The case for less protein was founded in the belief that kidney function decreases with age, and that pets with kidney disease should be protein restricted. In fact, studies indicate that structural changes associated with aging in the kidneys of geriatric dogs do not result in decreased renal function.
Kidney disease and dysfunction is most often diagnosed in geriatric pets, but as these studies indicate, it is not a result of age but a result of developing kidney disease by whatever cause (mostly idiopathic, meaning we haven’t a clue). The majority of geriatric pets do not have kidney disease.
Old research suggested that if a pet has kidney problems, normal protein levels in food would accelerate kidney dysfunction. We now know that this is not true. Elevated protein levels in the diet does not speed kidney failure. Low protein diets are used with patients with advanced stages of kidney disease to alleviate the symptoms of elevated blood ammonia levels due to kidney dysfunction (Geriatric Pets Need More Protein). These low protein diets designed specifically for kidney disease are not appropriate for geriatric pets without kidney disease. Such diets could accelerate the natural muscle tissue loss that does accompany aging.
Most newer, commercial geriatric formulas feature slightly higher levels of protein than regular diets. This strategy is based on the recognition that aging does result in a progressive loss of muscle tissue, or sarcopenia. Some studies have suggested that high protein diets can bring about muscle production in geriatric dogs and cats. Other studies have suggested that increased protein in the diet merely slows muscle loss. And still other long term studies in dogs have documented no difference in the amount of sarcopenia with diets containing either 16.5 percent protein or 45 percent protein.
It appears that a diet containing between 16 and 24 percent protein is adequate for geriatric dogs. Not surprisingly, most non-senior dog food contains 24 percent or more protein. A survey of special geriatric diets suggests that these formulas contain only about 4-8 percent more protein than the already adequate regular dog food.
The story is similar with cat food, although the percentages are much higher given the higher protein needs of cats. I am not against extra protein. The point is this: Just because a pet is geriatric does not mean it needs more protein than that already provided in its normal diet.
If an animal has adequate muscle mass, extra protein cannot be stored and will be used in three ways: First, it can be used as energy. Second, it can be converted to sugar or glucose for energy. Or thirdly, that glucose can be converted and stored as glycogen or, more likely, fat.
Avoid geriatric foods that feature less protein than your present dog or cat food. But don’t pay more for a “senior food” with extra protein if your dog’s regular diet already contains 24 percent or more protein (as dry matter) and your cat’s regular food contains 35 percent or more protein (as dry matter).
To calculate protein level on a dry matter basis you will need the label from the food. In the guaranteed analysis on the label, take the percentage of protein content and divide it by the percentage of moisture content.
As you will see in the example below, you must first convert the moisture percentage to decimal. Do this by placing a decimal point in front of the percentage (e.g., 10% becomes .10; 81% becomes .81) and then subtract it from 1. You will then us the resulting number to divide the protein percentage. The final answer is the protein level on a dry matter basis.
Dry Food: Label says 24% protein and 10% moisture: 24%/ (1-.1) = 24%/.9 = 26.7%
Wet Food: Label says 9% protein and 81% moisture: 9%/ (1-.81) = 9%/.19 = 47.4%
As you can see with this example, the protein levels are already adequate.
Next week's blog will look at other geriatric changes targeted by commercial geriatric food formulas.
Dr. Ken Tudor