Top 5 Complete Pelleted Diets for Senior Rats and Mice in the USA 2025 — Expert-Reviewed Options for Longevity, Digestion, and Cognitive Health (What Every American Owner Should Know)

Oxbow Essentials Senior Rat Food earns a top position for senior rodents by emphasizing timothy-hay–based, high-fiber pellets and moderated calorie levels to support dental wear and healthy weight in older rats and mice. Compared with lab-grade formulations like Mazuri it is more forage-forward and pet-focused, often offering better cost-per-serving for owners while maintaining consistent extruded pellet quality and strong ingredient traceability.

Mazuri Rat & Mouse Diet is a market leader in research- and colony-grade nutrition, formulated with tightly controlled macro- and micronutrient profiles that suit senior animals requiring predictable dietary inputs. It typically delivers greater specification and batch consistency than consumer pet brands, which is a technical advantage for facilities and owners who prioritize measurable nutrition, though it is generally priced higher than more consumer-oriented options on this list.

Supreme Science Selective Rat Food stands out for palatable, extruded pellets designed for selective eaters and older rodents, balancing moderate protein with elevated fiber to support digestion and weight management. Compared with bulk or topper-style offerings like Living World, it provides a compact, complete diet that is competitive with premium options while remaining widely available in pet retail channels.

Living World Green Gourmet pairs vegetable-rich toppers with complementary pellets to entice picky senior rats and mice, offering a budget-friendly, ingredient-diverse approach that encourages eating in finicky animals. While its complete-diet standardization is not as tight as Mazuri or Oxbow’s senior-specific formulas, its financial accessibility and flavor variety make it a useful primary diet for owners seeking value or a transitional solution for aging pets.