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Evidence collection15 August 2022

Unconventional diets for dogs and cats

Evidence-based veterinary practiceSmall animals

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Published 15 August 2022 | Updated 30 October 2025

Introduction

The subject of feeding pet dogs and cats seems to generate strong feelings, and there is an increasing range of options available. As veterinary professionals our concerns have focused on ensuring that the diet is safe and meets the nutritional needs of the animal, which may change with life stage and disease.

However, both the options available and societal expectations change over time, and there is now increasing discussion about sustainability and environmental impact. The term “unconventional” has been used to reflect the changes from what has become the conventional way of feeding dogs and cats with wet or dry manufactured pet foods based on ingredients with which we are familiar in our own diets.

The purpose of this collection is to bring together a selection of the most relevant published evidence and resources relating to some of the most common types of unconventional diets available for feeding dogs and cats. While there is little published about the long-term effects of feeding a particular type of diet there is an increasing body of evidence that can inform our discussions with pet owners, including some research about why owners make the choices they do in feeding their pets.

The papers are grouped to give a general introduction to unconventional diets and owner choices before going on to consider published evidence and resources available relating to the different types of diets now available. When interpreting the evidence, it should be remembered that broad terms such as “raw”, “vegetarian”, “grain free” or “homemade” can cover a range of diets which may have very different nutritional properties.

The final section looks at some of the emerging evidence on longer term effects on health from feeding different types of diet. It should be noted that this research is still in its infancy and many of the studies published so far rely on single time point reports from owners on the perceived health of their animals rather than longitudinal objective assessments.

Owner attitudes

Guidelines

Raw meat-based diets

The feeding of raw meat-based diets to dogs and cats is not new but has increased with the availability of commercially available raw diets. The majority of the published literature reflects a dichotomy between the owner perceived benefits of feeding a raw meat-based diet and concerns about the risks of microbiological contamination. While much of this research focuses on contamination with enteric bacteria (e.g. Salmonella and E. coli), there are also concerns about raw meat spreading parasites and other pathogenic organisms such as mycobacteria.

However, it is also important to consider whether a raw meat-based diet can meet the nutritional needs of the individual animal. Therefore, this section also contains links to papers reporting on the nutritional adequacy of raw diets with particular reference to mineral levels that impact on skeletal growth. It should be noted that the majority of reports of nutritional problems are published as case reports, which are not included here, as experimental work in this area raised ethical concerns.

Review articles

Owner perception

Microbiological contamination

Nutritional adequacy

Vegetarian and vegan diets

The reasons why owners may choose to feed their pet a vegetarian or vegan diet can vary but are likely to include those who choose to avoid meat or animal products on ethical grounds and those who are reducing the consumption of animal products based on environmental sustainability. However, this can raise concerns about meeting the nutritional needs of the pet, especially for cats which are obligate carnivores.

Owner attitudes

Nutritional adequacy

Grain free diets

Grain free diets may be considered a variation on conventional diets which may appeal to owners concerned about the ingredients in pet food.  However, there have been concerns raised regarding association of grain free pet food with canine dilated cardiomyopathy. This led the US Food and Drugs Administration (FDA) to launch an investigation into the links between reports of canine dilated cardiomyopathy (DCM) and certain pet foods. They stated that

“DCM itself is not considered rare in dogs, but these reports are unusual because many of the reported cases occurred in breeds of dogs not typically genetically predisposed to the disease and were reported to have been fed diets containing legumes like peas or lentils, other legume ingredients (pulses) or potatoes as main ingredients. Many of these products are labelled as “grain-free” or “zero-grain.”

This has led to a number of research studies to further investigate the effect of diet on the development and management of canine dilated cardiomyopathy.

Review articles

Research articles

Owner attitudes

Homemade

Historically many dogs and cats may have been fed on kitchen scraps. However, the current tendency to feed homemade diets is more likely to be motivated by owner concerns about feeding commercial petfood, particularly for animals that are perceived to have specific dietary requirements or require encouragement to eat because of disease. However, as with all diets it is necessary to ensure that the diet is meeting the animal’s nutritional needs, which may require specialist advice.

Nutritional adequacy

Novel ingredients

The term novel protein is used to describe protein sources that are not considered part of a conventional diet. There is currently significant interest in the use of insects as a sustainable protein source although clinical research in this area is currently limited.

For those interested in learning more about insects as a potential food source: Journal of Insects as Food and Feed. Wageningen Academic Publishers, ISSN: 2352-4588. Available from: https://www.wageningenacademic.com/loi/jiff [accessed 12 August 2022]

Comparing diets

There is currently little research comparing the effect of different types of diet on pet health, as with the exception of microbiological contamination or acute nutritional deficiency these studies need large sample sizes and long-term data collection. However, there are a number of research papers comparing owner perception of their pet health based on type of diet fed, although it is important to be aware of potential selection and reporting bias in these studies.

Owner perception

About evidence collections

Evidence collections bring together collections of published papers on topics of interest and importance to the veterinary professions. Papers are chosen for relevance and accessibility, with the full text of articles either being available through the RCVS Knowledge library, on open access or from other publications to which a significant number of veterinary professionals are likely to have access. This means that there may be relevant evidence that is not included.

If you would like assistance in searching for further evidence on this topic you may find the following helpful EBVM Toolkit 2: Finding the best available evidence.

If you would like to suggest a paper for inclusion in one of our published evidence collections, or a topic for a future collection, please email library@rcvsknowledge.org

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