Dietary Protein for older dogs
New Science Challenges Years-Old Notions About Protein’s Role in Cat & Dog Nutrition
Both old and new research have led to advancements in our understanding of dietary protein. The Nestlé Purina PetCare Research Centers (in St. Louis, MO; Gray Summit, MO; St. Joseph, MO; and Amiens, France) have conducted internal research and sponsored external research studies related to dietary protein and its application to veterinary medicine. Numerous studies conducted in companion animals (through all life stages and under different physiological conditions) have provided new species-specific results that validate the benefits of optimal dietary protein. This new science as well as that from independent research has put to rest many of the fallacies surrounding dietary protein.
The following research summaries will demonstrate that:
1) protein at any level consistent with complete and balanced nutrition has no adverse effects on the kidneys of normal, healthy dogs.
2) increasing dietary protein spares lean body mass in older dogs.
3) increasing dietary protein is important for successful weight loss.
4) modified proteins offer a more effective way to manage food hypersensitivity.
5) diabetic cats should be fed a diet high in dietary protein and low in carbohydrates to help moderate glucose levels.
If you have questions about this information, please contact the Purina Veterinary Resource Center by calling toll-free 1-800-222-8387 weekdays 8:00 a.m. to 4:30 p.m. CT.
Excess protein causes kidney damage in dogs.
Protein at any level, consistent with complete and balanced nutrition, has no adverse effects on the kidneys of normal, healthy dogs.
The primary concern regarding excess dietary protein in older dogs has focused on kidney function. It was suggested by Brenner that excess dietary protein would induce kidney damage, based on extrapolating research conducted in rodents. Subsequent research suggested that the benefits attributed to protein restriction were actually secondary to the reduced calorie intake associated with low protein diets.
I. Research in dogs with renal failure.
*Kronfeld published a critical review of 27 diets used in four clinical trials and 8 experiments and grouped each by protein content, as percent of dietary metabolizable energy (ME)4:
1) high (38-49% ME)
2) moderate (20-31% ME)
3) low (12-16% ME)
4) very low (7-9% ME)
*In dogs with chronic renal failure, responses were undesirable with the high or very low protein diets.
*Moderate protein diets (up to 34% of diet or 31% of energy) had no detrimental effects in dogs with chronic renal failure and were associated with general improvement over dogs fed high or very low (less than 10% of energy) protein diets.
*Excessive restriction of dietary protein (<10%) was associated with adverse effects in dogs with chronic renal failure.
II. In uninephrectomized older dogs (6-8 years of age) fed a dry diet containing either 18% or 34% protein or a canned diet containing 22-36% protein on a dry matter basis for four years, no adverse effects from dietary protein were observed.
III. Research in healthy geriatric dogs.
*Kealy et al. reported that healthy, geriatric dogs fed a 45% protein diet maintained health and body condition, with no evidence of increased kidney damage due to protein intake.
Older dogs should consume less protein.
Increasing dietary protein spares lean body mass in older dogs.
Decreasing dietary protein levels for senior dogs may not be appropriate. Older dogs appear to be less efficient in metabolizing dietary protein compared to younger animals. In order to maintain protein reserves and maximize protein turnover rates, older dogs may thus require more dietary protein than their younger counterparts.
I. Lean body mass decreases with age.
*Numerous studies in multiple species have shown that increased dietary protein intake can slow the age-associated loss in lean body mass.
*Decreases in lean body mass can be detrimental. The skeletal musculature plays a critical role in recovery from trauma or infection.
*Skeletal muscle and skin proteins are he primary source of endogenous proteins involved in protein turnover. Protein turnover is a dynamic process of catabolism and synthesis of endogenous protein, which takes place almost continuously in all cells.
*Protein turnover helps animals adapt to their ever-changing environment by maintaining a readily available supply of amino acids necessary to produce proteins or enzymes needed at any given time. A reduction in protein turnover can lead to decreased immune comptetnce and increased susceptibility to stresses such as infection and injury.
*Kealy et al. compared the effect of feeding either 16.5% or 45% dietary protein in healthy, older dogs. While all dogs lost lean body mass with age, the rate of decline was significantly reduced by feeding a higher dietary protein level.
II. Maintenance energy requirements (MER) decrease with age.
*Using older dogs, Powanda reported a significant age-related decline in maintenance energy requirements (MER).
*This decrease in MER was associated with a decline in physical activity levels and approximated a 20% decline in MER.
III. Older dogs require an increased percentage of calories from protein.
*Laflamme et al. reported a 25% reduction in MER with age in dogs.
*To meet the senior dog’s increased protein requirement while avoiding excess calorie intake, senior dog diets should be formulated with an increased protein:calorie ratio. Nestlé Purina recommends at least 25% of calories as protein in diets for older dogs.