Homemade diets – good or bad?

Introduction

The term “homemade” when applied to petfood encompasses any non-commercial diet, and covers the entire spectrum from meat-only recipes to vegetarian or vegan diets, and includes both cooked and raw ingredients. Most owners who decide to prepare their pet’s food wish to provide what they perceive as excellent nutrition for their cat or dog. Whilst they may seek the help of a board-certified veterinary nutritionist^®, they may also – and are perhaps more likely to – source recipes from books, the internet, friends, and others who lack adequate training in small animal nutrition. This article offers an overview of such diets and discusses the risks and potential benefits that they may bring. 

The prevalence of homemade diets

It can be difficult to determine an exact figure on how many pets receive a homemade diet. For example, a 2008 survey in the USA and Australia revealed that over 93.2% of dog owners and 98.9% of cat owners reported at least part of their pet’s diet included commercial foodstuffs 1. However, 30.6% of dogs and 13.1% of cats received table scraps, leftovers or homemade foods, and bones or raw food was included in the pet’s main meal in 16.2% of dogs and 9.6% of cats. Over 80% of people who included bones or raw foods in their pet’s diet were residing in Australia. Less than 3% of owners fed exclusively home-prepared diets, but approximately 7% of dogs received at least half their diet as home-prepared foods.

Another study from the same year found that 95.5% of owners fed their cat a commercial diet, with only 2.7% meeting the criterion for offering a non-commercial diet, whilst 86.8% of dog owners were classified as “commercial” feeders and 10.0% as “non-commercial” feeders, with the remaining 3.2% not meeting the criterion for either category 2. A more recent international study reported that 79% of dogs and 90% of cats were fed conventional commercial foods, although only 13% of dogs and 32% of cats were fed such diets exclusively 3. Homemade food was offered to 64% of the dogs and 46% of the cats, with raw food being given to 66% of dogs and 53% of cats. As noted in the study above, feeding homemade and/or raw foods was again more prevalent in Australia, and there are obviously considerable geographical differences when it comes to pet feeding practices. In contrast to the above studies, 42% of dogs in Sri Lanka are reported to be fed home-cooked food, whilst only 18% are fed commercial diets, with the remaining 40% getting a mixture of both options. In addition, the same study showed that 49% of dogs receive milk as a separate meal as well as their normal diet, and 57% receive dietary supplements 4.

Overall, these and other surveys report the prevalence of owners feeding homemade diets to dogs appears to be about 7-10%, and to cats less than 4%; however, such results may not reflect the overall pet-owning population, due to selection bias. For example, in one of the above studies 3 the survey was completed by owners chosen via self-selection from canine and feline interest groups on social media. This type of sampling can skew results due to feedback from potentially biased segments of the population – for instance, owners who feed homemade diets may be more interested in doing a survey on feeding practices, or conversely could be less likely to report their feeding practices, so it is difficult to ascertain the real percentage of owners feeding homemade diets.

Why choose a homemade diet?

Pets are often considered to be family members, and the decision on what diet to offer may reflect an owner’s cultural beliefs, ideologies and identity. So individuals may wish to feed according to their own eating philosophy, such as using only vegan, organic or natural foods. With the humanization of pets, offering a meal which looks more like the owner’s dinner may have some appeal. Other reasons for feeding homemade foods include palatability (i.e., choosing foods the pet prefers), mistrust and/or misunderstanding of petfood processing, a wish to exclude certain ingredients (such as grains, meat by-products or meat derivatives), or a desire to have “better” control over the pet’s diet (Figure 1). Owners have also reported motivations for feeding home-prepared or raw foods to include a desire to pamper their pet, concerns that commercial foods may be less wholesome or nutritious than desired, or to achieve a real or perceived medical benefit 2 (Table 1).

Table 1. Some reasons stated by owners for feeding homemade diets.

At least one study has suggested that there is an association between concerns of pet owners about commercial pet foods and the practice of feeding home-prepared foods. Owners who fed their pets a diet that consisted of at least 50% non-commercial foodstuffs had more concerns and misgivings about commercial petfood, food processing, and the petfood industry than owners who gave their pet at least 75% commercial products 2. These non-commercial feeders also had more positive attitudes toward raw and home-prepared diets than commercial feeders. Owners feeding home-prepared foods were more likely to believe that processed foods for pets are unhealthy, that cooking destroys vital nutrients, and that organic foods are safer and healthier than other foods. Some individuals also enjoy preparing their pet’s food, which could potentially influence their responses 2.

Proponents of raw food diets reportedly feel that raw foods and a high-protein diet provide more natural nutrition, comparable to that consumed by wild canids and felids 1. In a study of 218 owners who fed raw foods to their dogs, 26% indicated the main reason was to respect the dog’s carnivorous nature, 24% to improve the pet’s health, 21% because commercial diets had caused problems in the past, 19% because they did not trust commercial pet food, 6% because their dog did not eat commercial pet food, and 4% stated another reason 5. The main advantage of feeding a raw diet was thought by 57% of these owners to enable total control over the diet and awareness of its composition, while 23% cited their preference for animal proteins as the principal dietary component; 11% of owners cited the perceived benefit that it took a longer time for the meal to be eaten, along with the animal’s apparent consequent greater satisfaction, to be the prime advantage. Only 3% of respondents considered good palatability, 1% the absence of carbohydrates, and 1% the rawness of the ingredients to be the main advantage.

Homemade diets for nutritional therapy

Although there are a wide variety of commercial pet foods available for healthy pets and for those requiring therapeutic diets, homemade diets can be useful where there is no preparation available that is suitable for an individual animal with specific problems. For example, for a dog with chronic pancreatitis and kidney disease, a suitable homemade low-fat, low-phosphorus diet can be formulated by a veterinary nutritionist, and a diet with a fat content lower than that found in commercial foods can be useful for some intestinal disorders, such as lymphangiectasia. Some animals will also have adverse reactions to multiple food ingredients and can benefit from a bespoke diet. Homemade diets may also be more palatable in some situations, as the owners (and pets) can select their preferred foods; this can be especially useful in cases such as chronic kidney disease, where the pet’s appetite may be poor, although also potentially deleterious with overweight pets.

It has been proposed that homemade diets can be more digestible than both dry and wet commercially available options, resulting in better quality or smaller feces. However, there are various factors that affect a food’s digestibility, including the ingredients, the amount and types of fiber, and the different heat processing techniques. One study in cats fed a dry diet, a raw diet and the same “raw” diet but cooked showed higher apparent fecal digestibility of the raw and homemade vs. the dry food 6. Another study comparing fecal digestibility of two raw diets and a dry cooked diet in kittens showed the digestibility of organic matter, protein and energy was higher for the raw products, resulting in smaller feces, but no difference in fecal score 7. These studies compared diets with both a variety of ingredients and processing, so the effects of processing alone are difficult to determine.

As long as digestibility is high enough to provide adequate nutrition, increased digestibility of a petfood is not necessarily beneficial for all pets. Overweight pets needing lower calorie density, and animals that require a lot of fiber in their diet for colonic health may benefit from increased dietary fiber that has lower digestibility. Conversely, high digestibility can benefit some patients with some small intestinal diseases or those requiring higher caloric density.

Potential problems with homemade diets

Nutrient imbalances

There are numerous case reports and case series of problems resulting from feeding nutritionally unbalanced and/or incomplete homemade diets (Table 2). Many of these involve growing puppies or kittens, where nutrient imbalances are more critical, but they are also reported in adult dogs and cats 8,9. Metabolic bone disease and nutritional secondary hyperparathyroidism occur when dietary calcium is deficient or the calcium: phosphorus ratio is incorrect (Figure 2), and can occur simultaneously with rickets due to vitamin D deficiency. Abnormalities reported in dogs fed homemade diets include hypovitaminosis D, hypocalcemia, vitamin A deficiency 10, hyponatremia, hypochloremia, hyperphosphatemia, and taurine deficiency 11. There are reports of skeletal disease in kittens associated with unbalanced homemade diets due to calcium and/or vitamin D deficiencies 12. Pansteatitis from consumption of high-fat diets with insufficient vitamin E has been reported in cats fed unbalanced homemade diet 13. A diet comprised mostly of liver fed to cats can result in hypervitaminosis A, causing irreversible extensive bony osteophytes and exostoses resulting in pain and lameness. Of course, many nutrition-related cases in practice go unreported, so the actual prevalence of these disorders is not known.

Table 2. Common nutrient deficiencies in homemade maintenance pet diets.

Nutrient analyses of homemade recipes

Several studies have analyzed recipes for homemade diets, all of which reported deficiencies in most of the published recipes 14,15,16 (Figure 3). A study of 200 homemade maintenance diets for dogs (64.5% written by veterinarians and 35.5% by non-veterinarians) from 34 sources determined that most were not nutritionally complete 14. Of these recipes, 92% had vague or incomplete instructions (e.g., regarding ingredients, method of preparation, and supplements) and 29% omitted supplements. Calories per recipe varied from 380 to 16,348 kcal, and whilst there was at least one essential nutrient below NRC* or AAFCO** guideline in 95% of the recipes, 83.5% had multiple deficiencies. The most common deficiencies were a lack of vitamin D, vitamin E, zinc, choline, copper, omega-3 fatty acids and calcium. A study of 114 homemade diets for cats found similar vague, inadequate instructions and nutritional deficiencies, notably in choline, iron, thiamine, zinc, manganese, vitamin E, and copper. None of the recipes met the recommended NRC nutrient allowances 16.

* NRC = National Research Council
** AAFCO = Association of American Feed Control Officials

With regard to therapeutic diets, another study reported that none of 67 homemade renal diet recipes for dogs and cats (taken from veterinary texts, pet-owner books and websites) met all of the NRC nutrient recommendation. There were frequent amino acid deficiencies, and many recipes were low in choline, selenium, zinc, and calcium 17. However, one report cites 18 dogs with CKD and hyperkalemia which had been fed commercial therapeutic renal diets; when switched to a potassium-reduced homemade renal diet devised with the supervision of a board-certified veterinary nutritionist^®, serum potassium concentrations had reverted to normal in all but one dog within one to two weeks 18.

Many published recipes will include the use of a non-specific vitamin and mineral supplement. These products vary in their constituents, and most of the ones sold for pets are not formulated for use with homemade diets. In addition, some supplements designed for human use may contain vitamin D levels which can be excessive for dogs and cats. Human supplements are also unlikely to contain taurine, which is essential for cats and may or may not be sufficient in a homemade diet. For example, one study showed that whole rabbit samples did not meet any nutrient recommendation for taurine dietary concentrations, ranging from 20 to 90% of the minimum values 19.

It is often suggested that rotation of different dietary formulations provides a variety of nutrients which will compensate for any deficiencies in any one of the diets, but a study that analyzed the effect of rotating seven separate recipes showed that the deficiencies were not eliminated 14. As many homemade recipes have similar deficiencies (e.g., zinc), alternating recipes will not provide a complete and balanced diet. 

Figure 3. The results of a computer analysis using Balanceit^®.com software to assess an internet homemade diet recipe for an adult dog based on turkey, rice, and mixed vegetables. The figures in grey denote sufficient levels for a given nutrient, while the figures in red represent nutrients which are deficient. 
Credit: Balanceit.com 

Diet formulations

Even with a well-formulated diet, nutrient imbalances may occur, as the diet fed will only correspond with the computer formulation if the actual ingredients are consistent with those in the database. One study has shown good consistency when diets were chemically analyzed and compared to the computer analysis 14, but owners may not choose the exact ingredient recommended, and (for example) the amount of fat in ground meats can vary considerably. More pertinently, pet owners will often modify the recipes they are given, a process known as recipe or diet drift. Modifications may include changing amounts of ingredients, adding, omitting, or substituting ingredients, or omitting or changing supplements. Any of these variations can alter the nutritional composition of a diet and could potentially make it unsuitable.

Nutritional problems have been identified in commercial pet foods as well; for example, thiamine (vitamin B1) concentrations below the AAFCO minimum were identified in 12 of 90 US canned cat foods, especially in pâtés and products made by smaller companies 20. There have been recalls of commercial pet products associated with vitamin D excess, for example resulting from a mistake in a premix used in dog foods. These errors should be found at quality testing and result in recalls being made to remove the affected batches. The potential for ration imbalance therefore underlines the importance of quality control and regular nutritional analysis of pet foods. This is an inherent disadvantage of homemade diets, as there is no quality control involved in their preparation and, unlike commercial diets, such recipes are usually not tested for nutrient balance or safety. Essentially, the “feeding trial” is made on that individual pet. Even if an owner selects the food correctly and does not change the recipe, an exact match with the database cannot be ensured, especially over a prolonged period of time, as the food suppliers may change what is available. This is especially important in pets fed homemade therapeutic diets, as it may affect their disease management.

Cost

Owners may wish to feed homemade diets because they believe it will save money; however, one study showed complete homemade diets for dogs are usually more expensive than commercial dry food, although they can be cheaper than some canned diets 21.

Raw food risks

Homemade diets may include raw meat-based products and bones. Chewing on large bones does not provide sufficient dietary calcium, does not prevent dental plaque or periodontitis, and can cause tooth fractures. Raw meat-based diets, whether homemade or commercial, can be a health risk for dogs, cats, and their owners due to potential pathogen contamination. While this has occasionally also been reported in dry commercial cooked petfoods, it is uncommon, as such products are processed at high temperatures which kill bacteria. Contamination is even more unlikely in unopened canned foods, as they are sterilized in the can. Microbiological contamination is much more likely with raw foods, and has been reported numerous times; for example, various studies have noted commercial raw frozen or freeze-dried pet foods to be contaminated with a variety of zoonotic bacterial and parasitic pathogens 22,23.

It is not possible to know what percentage of raw homemade diets are contaminated, as they are not monitored, but the prevalence of contamination of meat and poultry products for human consumption is known. A meta-analysis of 78 studies conducted in 21 European countries showed that Staphylococcus aureus was the main pathogen, being detected in 38.5% of poultry meat (with a range of 25.4-53.4%), followed by Campylobacter species at 33.3% (22.3-46.4%). Listeria monocytogenes and Salmonella spp. were present at a lower prevalence at 19.3% (14.4-25.3%) and 7.1% (4.60-10.8%), respectively 24.

Importantly, whilst owners may not see overt clinical signs of bacterial infection in animals fed contaminated raw foods, the pets can still be shedding pathogens in their feces and saliva. The fecal shedding of pathogens constitutes both a public health hazard and a risk to household members, especially those who are immunocompromised, young, elderly or pregnant. Raw feeding may also contribute to bacterial antibiotic resistance; such foods have been identified as a risk factor for shedding of extended-spectrum beta-lactamase-producing Enterobacteriaceae in household cats 25.

Discussing diet choice with owners

Owners may have strong feelings about their choice of diet for their pet, so nutrition can be a challenging discussion. It is important to ask about feeding as part of the nutritional assessment, and to have a non-judgmental discussion about the reasons for the choice of diet (Figure 4). Owners may have misperceptions about ingredients or processing of commercial pet foods, and may have obtained their “data” from biased and misinformed online or book sources, so it can be appropriate to ask the owner if they would like more advice. In particular, when the diet being fed may not be complete or balanced, as is the case for most homemade recipes, providing information about the pet’s nutritional requirements may help, and where there is a risk for, or the presence of, a diet-related disorder (such as nutritional secondary hyperparathyroidism in a young animal), there is some urgency in correcting the diet. Providing highly visual and written information is more effective than only verbal advice, which may not be recalled correctly or may be misinterpreted.

The healthcare team should recognize that the owner’s feeding choices were likely made in the hope that they were in the best interest of the pet. Positive aspects of the owner’s management and care for their pet should be noted; if an owner feels that they are being judged for poor management of their pet, they are more likely to become defensive and less likely to implement the necessary dietary changes. Once an owner is willing to contemplate a change in feeding, a definitive plan should be outlined for transition to a complete and balanced diet, and can include the options of switching to a commercial diet, utilizing a program and supplement such as that provided by a reputable website (e.g., Balanceit.com), or being referred to a board-certified veterinary nutritionist^®.

Conclusion

While owners may choose a homemade food for their pet because they believe it to be the healthiest – or possibly only – choice available, they should be aware of the potential risks involved, as well as any perceived benefits. Ultimately, any diet should be as safe from pathogens as possible, and must deliver complete, balanced nutrition including appropriate supplements. The clinician should strive to include dietary advice whenever appropriate during a consultation, as omission could lead to a nutritionally related disorder in either the short or longer term for the pet.