Nutrition and ageing in dogs and cats: Physiological keys and dietary strategies

The increasing life expectancy of dogs and cats has transformed both veterinary medicine and pet food formulation. Nutrition is recognised as one of the most influential factors in the quality and duration of a pet’s life, due to its role in maintaining lean mass and modulating the chronic inflammation associated with ageing.

Recent scientific evidence emphasises that ageing in companion animals should not be confused with disease, although the two processes interact. Immunosenescence, sarcopenia, sensory decline and digestive changes are physiological phenomena that can be mitigated through specific nutritional strategies.

Physiological changes of ageing with nutritional impact

Ageing affects all biological systems, but certain changes are particularly relevant to nutrition and the formulation of adapted diets:

Body composition and sarcopenia
Progressive loss of muscle mass is one of the most consistent markers of ageing. A selective reduction in type II muscle fibres and an increase in visceral fat are observed, promoting insulin resistance and frailty. Preserving lean mass is considered a key factor for healthy longevity.

Digestion and absorption
Although overall digestibility does not appear to decline markedly, several relevant changes occur:

• lower tolerance to diets very high in soluble fibre
• intestinal morphological changes that may affect absorption
• alterations in the microbiome, with reduced lactobacilli and shifts in fermentative metabolites

Senses and appetite
Reduced smell and taste can decrease voluntary food intake, making palatability a therapeutic component in senior animals.

Renal and hepatic function
Glomerular filtration rate may decline slightly with age, although individual variability is high. This does not justify systematic protein restriction, but it does require close monitoring of renal status.

Preserving lean mass and continuously assessing body condition are central pillars of senior pet nutrition.

Table 1. Physiological changes of ageing with nutritional implications

GFR: Glomerular filtration rate.

Nutritional requirements in senior pets

There are no universal geriatric requirements, but rather principles that must be adapted to the individual.

Energy
Maintaining optimal body weight is a priority. Energy needs may decrease in some senior animals, although variability is high and depends largely on lean mass.

Protein and amino acids
Current evidence rejects protein restriction in healthy senior animals. Highly digestible protein helps preserve muscle mass, and adequate intake of essential amino acids is critical for tissue renewal. Protein is adjusted only in cases of advanced renal disease.

Minerals and vitamins
Phosphorus should be controlled but not restricted in the absence of renal disease. A calcium:phosphorus ratio >1 is recommended. Antioxidants and long‑chain omega‑3 fatty acids (EPA and DHA) may improve cognitive function and reduce inflammation.

Nutritional assessment in clinical practice

Nutritional assessment in senior pets should be understood as a continuous process integrating ageing physiology, frailty and changes in body composition. This approach allows deviations to be detected before they become clinically evident and enables precise dietary adjustments.

Key elements of nutritional assessment:

• Body condition
• Muscle condition
• Complete dietary history
• Appetite and feeding behaviour
• Relevant comorbidities
• Frailty factors

Dietary adaptation in senior pets

Dietary adaptation does not consist of applying a “standard geriatric diet”, but of adjusting nutrition to physiology, lean mass, digestive tolerance and clinical status. Digestibility, energy density and protein quality are fundamental pillars, together with modulation of chronic inflammation through specific nutrients.

Key aspects for dietary adaptation:

• High digestibility (protein digestibility >80%)
• High‑quality protein
• Individualised energy adjustment
• Phosphorus control according to renal status
• Omega‑3 supply (EPA + DHA)
• Moderate fibre
• Adequate antioxidants

Digestive, sensory and microbiome changes require highly digestible, palatable diets tailored to individual tolerance.

Feeding frequency and form

How the diet is offered becomes increasingly important in senior animals due to sensory, digestive and behavioural decline. Food presentation can directly influence intake and quality of life.

Practical feeding recommendations:

• Divide the daily ration into 2–4 meals
• Increase palatability
• Combine formats (dry + wet)
• Adapt texture
• Avoid abrupt dietary changes
• Provide gentle environmental enrichment

Table 2. Practical nutritional recommendations for senior dogs and cats

There is no universal geriatric diet: nutritional adaptation must be based on physiology, comorbidities and the progression of frailty.

Conclusions

Nutrition is a central tool for prolonging healthy life in dogs and cats. Preserving lean mass, controlling weight and optimising protein intake are fundamental pillars of geriatric nutrition. The physiological changes of ageing require diets that are digestible, palatable and adapted to individual variability. Continuous nutritional assessment allows early detection of problems, dietary adjustment and improved quality of life.

References

Bermingham, E. N., et al. (2024). Nutritional needs and health outcomes of ageing cats and dogs: is it time for updated nutrient guidelines? Animal Frontiers.
Blanchard, G., et al. (2025). Nutrition and ageing in dogs and cats: assessment and dietary strategies. Journal of Veterinary Science.
Stockman, J. (2024). Nutrition and Ageing in Dogs and Cats. In: Nutrition and Metabolism of Dogs and Cats. Springer Nature.