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Every living creature on our planet has evolved to thrive in a specific environment, and has become specialised in using certain food sources to fuel its survival—and that of its kind. The cat is no exception.

Pet food companies typically base their formulations on data drawn from decades of individual feeding trials and experiments. These findings have been compiled in reference works such as the Nutrient Requirements of Dogs and Cats, published by the National Research Council. This kind of work adheres strictly to the scientific method, ensuring precision and accuracy.

Unfortunately, this precision has come at a significant cost—the lives of thousands of cats used in laboratory testing, kept in controlled environments, and ultimately sacrificed to provide this information. While the data gained is undoubtedly valuable, the means by which it was obtained raise serious ethical concerns, even if the intention was to serve the greater good.

An alternative—and less invasive—way of learning about the natural diet and nutritional needs of cats is through observational study. Long before the results of scientific experiments were ever published, nature had already provided us with a remarkably precise blueprint for feline nutrition.

It starts with taxonomy, and is supported by modern DNA research, which has enabled us to identify the wild counterpart of the domestic cat. Genetically, domestic cats (Felis catus) remain virtually unchanged from their ancestor, the African wildcat (Felis lybica). The differences we see in physical appearance today are the result of human-directed breeding and the enhancement of natural mutations, not genetic divergence.

Biologists know from field observations—and the study of scat—exactly what wild feline species eat in their natural habitats. These studies tell us that the African wildcat, across its range in sub-Saharan Africa, North Africa, and Southwest Asia, primarily preys on rodents. As such, our domestic cats, who are simply a tamed version of the African wildcat, are fundamentally rodent hunters.

Modern nutritional analysis allows us to break down the composition of food in minute detail. Analysing the nutritional profile of rodents, therefore, offers valuable insight into the true dietary needs of domestic cats. Simple feeding trials and observational field studies can help us determine how many mice a cat needs to consume each day to support survival, activity, reproduction, and the growth of kittens. From that, we gain a very accurate picture of the daily requirements for each nutrient—assuming, quite reasonably, that the natural diet is the ideal diet, having been refined by millions of years of adaptation.

Together, this knowledge gives us a clear answer to the question of what constitutes optimal nutrition for cats. The real challenge lies in translating that knowledge into a practical solution—one that modern cat owners can live with. After all, most people are understandably reluctant to feed their cat four or five mice a day.

That’s where innovation comes in.

My goal has been to “reinvent the mouse” using ingredients commonly found in the human food chain. With the right meats and carefully selected supplements, we can create a raw meat-based diet that mirrors the natural prey diet in nutritional value. The result is a practical, acceptable, and biologically appropriate alternative to feeding whole prey.

Of course, this less scientific method of understanding feline nutrition doesn’t tell us everything. It doesn’t determine minimum nutrient requirements, or the potential toxic effects of excessive intake. While such information can be interesting and even important, it isn’t necessary when you’re recreating a natural diet. It only becomes essential when attempting to formulate food from low-cost fillers and by-products.

In such cases, manufacturers need to know just how far they can stretch the cheaper ingredients before harming the animal—how much they can reduce the quality without causing outright deficiencies. That’s not the kind of formulation approach I’m interested in.

The Mouse Project: Nutritional Analysis of Wild Rodents

In August 2008, I began collecting wild rodents for nutritional analysis. My aim was to compare the composition of my raw meat cat food formula to that of a cat’s natural prey. I chose wild rodents specifically because I didn’t want the content of the digestive tract in captive-bred rodents—whose diets may be unnatural—to skew the results.

At the time, I also knew relatively little about what rodents eat in the wild. A poor or unnatural diet could lead to subclinical disease in captive rodents, which would then affect the nutritional quality of their tissues—giving a false picture of what a healthy prey animal would offer nutritionally. I wanted results that reflected real, natural prey, not the lab-bred equivalent.

The rodents which I collected on location on our farm in British Columbia were the native Deer Mouse (Peromyscus maniculatus) and the native Meadow Vole (Microtus pennsylvanicus). Neither is related to the House Mouse (Mus musculus). The House Mouse has likely been the predominant prey of cats since domestication, while the pet Gerbil (Meriones unguiculatus) is probably most similar to the rodent species of Africa which are hunted by the African Wildcat. Because my objective was the analysis of WILD rodents, I did not make use of readily available captive-bred House Mice or Gerbils, however.

The Deer Mice for the analysis were caught in mouse traps and by some of my cats, while all voles were caught by one of my cats. Only absolutely fresh specimens were used. They were weight, dated, cataloged, and then bagged and frozen whole immediately. Although I had collected enough specimens of both kinds of rodents by the end of September 2008, I decided to prepare only the mice for nutritional analysis due to financial restraints.

In March of 2010, the mice were ground whole while frozen, portioned for analysis, labelled, and returned immediately to the freezer. They were shipped in an insulated container via courier service to the laboratory. Two separate portions of the same sample were supplied, because the laboratory insisted on a microbiology analysis to determine if the material should be considered hazardous. The results from the microbiology analysis are of great interest in light of cats eating mice as they are -whole and raw.

The nutritional analysis of the wild caught mice sample included the macro nutrients protein, fat, carbohydrates, as well as moisture and total ash. In addition, a complete scan of all minerals and trace minerals was done, which included iodine as a special order. Taurine and Vitamin A and E were also analyzed. The microbiology analysis included a Coliform and E.coli plate count, Listeria mono, Salmonella, and Staph. aureus.

The results from having analyzed the wild Deer Mice were then compared with available data of basic nutrient compositions of vertebrate prey, which included domestic mice, fed in zoos. Of course, and most importantly, the analysis results were then compared with my raw meat cat food formula. The analysis of the wild Deer Mice confirmed the suitability of my formula as a staple food for cats, because the nutrient compositions were extremely similar to each other. The analysis of the wild mice enabled me to fine-tune the raw cat food formula.

Frozen Deer Mice

Ground Mice

Frozen ground mouse off to the laboratory