Materials and Methods

Veterinary therapeutic CPDs from 4 major pet food companies were categorized based on the following dietary approaches: (1) highly digestible (not low-fat; dry, n = 4; canned, n = 4), (2) low-fat (dry, n = 4; canned, n = 4), (3) novel or limited ingredient diets (dry, n = 12; canned, n = 7), (4) hydrolyzed protein (dry, n = 8; canned, n = 4), or (5) fiber-enriched (dry, n = 3; canned, n = 1)—specifically, diets designed for fiber-responsive enteropathies, including a blend of soluble, insoluble, and prebiotic fibers. Specific diets that were compared are included in Supplementary Table S1. Prices of all available package sizes (bags and cases) for each CPD were obtained from a national online retailer (www.chewy.com) in May and June 2021, and the cost (US$/100 kcal) was calculated for each diet based on manufacturer-reported calorie content.

Two board-certified veterinary nutritionists from the American College of Veterinary Internal Medicine Nutrition Specialty formulated 6 complete and balanced HCD recipes formulated to meet the guidelines for canine adult maintenance per the 2021 Association of American Feed Control Officials (AAFCO) nutrient profiles on a 1,000 kcal (Mcal) basis.¹⁷ The cost of feeding dogs of 3 different sizes (5, 20, and 40 kg) their daily maintenance energy requirement (MER) was calculated using the equation [1.6 X (70 X BW_kg^0.75)],¹⁸ where BW_kg is body weight in kilograms, for all HCDs, and dry and canned CPDs.

There were two recipes for each of these types of diet: (1) highly digestible, 85% lean ground beef and white rice or 93% lean ground turkey and white rice; (2) low-fat, chicken breast and white rice or pork loin and white potatoes; and (3) novel and limited ingredient, venison and white potatoes or rabbit and white potatoes. To mimic the CPDs in our HCDs, median macronutrient concentrations (measured in grams per Mcal) were determined (Table 1). Mimicking the dietary protein and fat concentrations was prioritized. The protein and carbohydrate ingredient sources chosen were comparable to the CPDs or were ingredients that are becoming increasingly prevalent in HCD formulations. Fruits and vegetables were not incorporated into these recipes because their availability is variable depending on season and geographic region, and selection is dependent on client and patient preference.

To meet linoleic acid (LA) requirements, either corn or canola oil was added. To maintain the ratio of LA + arachidonic acid (AA) to eicosapentaenoic acid (EPA) + docosahexaenoic acid (DHA), a ratio between 5:1 and 10:1 (Omega-3 Pet Liquid, Nordic Naturals) was used (rounded to the nearest ⅛ teaspoon per daily recipe). The median ratio of LA + AA to EPA + DHA in the included CPDs was 8.4:1 (range, 1.7:1 to 26.3:1). Balance It Canine, a food-grade multivitamin, multimineral, amino acid supplement was added to fortify the diet recipes, rounded to the nearest ⅛ teaspoon to ensure that AAFCO minimum nutrient requirements were met. The calcium-to-phosphorus ratio was maintained between 1:1 and 2:1 in all HCD recipe formulations. For any potato-based diet, when necessary, a methionine supplement was added to maintain the recipe’s methionine concentration greater than 200% of the AAFCO minimum requirement. The arbitrary doubling of the minimum requirement was done out of an abundance of caution, given the recent concern for diet-associated dilated cardiomyopathy, which has been associated with feeding grain-free and pulse-containing diets to dogs.^19,20

Hydrolyzed protein diets could not be mimicked successfully given the inability to purchase hydrolyzed proteins. Although no dry or canned ultralow-fat CPDs are available, given their utility in the management of CCEs, two ultralow-fat limited ingredient diet recipes (tilapia, sweet potatoes, and wheat pasta or shrimp and tapioca) were formulated.

Upon attempts to formulate fiber-enriched CPDs, it became apparent that it would be impractical to have an owner supplement the volume of fiber-containing ingredients required to match the median total dietary fiber (TDF) of the fiber-enriched CPDs (57 g TDF/Mcal). Instead, 1 specific base recipe (the low-fat chicken and white rice HCD formulated for a 20-kg dog eating its MER of 1,059 kcal/day) was manipulated in a few ways to demonstrate how its fiber concentration could be modified to match the median TDF of the low-fat CPDs (23 g TDF/Mcal). First, the rice was replaced with barley, a carbohydrate inherently higher in fiber. Then, various amounts of psyllium husk, canned pumpkin, and green beans were added, maintaining the caloric density and median macronutrients of the low-fat CPDs (75 g protein/Mcal, 22 g fat/Mcal, 23 g TDF/Mcal; Table 3).

After the HCD recipes were formulated, market research was conducted to determine the cost to feed each recipe on a US$/100-kcal basis. Three grocery store chains with a large national presence within the United States (ie, Walmart, Kroger/Ralph’s, and Aldi) were visited on 2 separate occasions within a 1-month time frame (July to September 2021) to gather data regarding ingredient costs. Item description, universal product code number, and cost of each ingredient were recorded. Data were collected from 2 geographic regions—the Mid-Atlantic (Christiansburg, VA) and the Midwest (Columbus, OH)—to account for variation in costs of ingredients (Supplementary Table S2).

Because venison and rabbit meat were unable to be located at these stores, costs for these ingredients were obtained from 3 online meat retailers (ie, Fossil Farms, Exotic Meat Market, Farm Foods Market). Tapioca pearls were not readily accessible in all local grocery stores; thus, prices were obtained from online stores (Walmart.com, Kroger.com) to obtain ingredient pricing.

Costs of supplements were obtained from 1 to 4 retail websites (ie, balanceit.com, nordicnaturals.com, chewy.com, or Amazon.com) per supplement. The various sizes of Nordic Naturals fish oil supplement (2 fl oz, 8 fl oz, and 16 fl oz) were used for the 5-, 20-, and 40-kg recipe variations, respectively, because of a manufacturer expiration date of 3 months after opening. Last, taking into account all ingredients in each recipe, the final cost of feeding each diet (US$/100 kcal) was determined for each of the 3 different dog sizes.

Descriptive statistics were performed for diet cost data based on diet type. All price data are reported as US$/100 kcal. Normality was evaluated via Shapiro–Wilk, and visual inspection graphically using histograms. Statistical analysis using commercial software (Prism version 7; GraphPad) was performed using the Kruskal–Wallis test. Multiple comparison testing on data was completed using the Dunn’s multiple comparisons test. The level of significance for all tests was set at P < .05.

Results

The median costs (US$/100 kcal) for HCDs and CPDs, both dry and canned, are provided in Table 2. The Kruskal–Wallis test of differences between US$/100 kcal cost of all dry, canned, and HCD diets in the study revealed statistically significant differences in cost (P < .001). Post hoc testing with Dunn’s multiple comparisons test revealed significant differences between the cost of dry and canned CPDs (P < .001) as well as between the cost of dry CPDs and HCDs (P = .003).

Cost analysis based on body weight

Median diet cost (US$ per 100 kcal) did not differ among dogs of different sizes. Daily costs to feed dogs their MER using the various dietary options are provided in Table 4. The median monthly costs per kilogram body weight of HCDs and CPDs are presented in Figure 1. As expected, it costs more money to feed larger dogs, given their higher daily caloric needs.

Table 4

Daily cost (US$) of home-cooked diets (HCDs) and veterinary therapeutic commercially prepared diets (CPDs), dry and canned, for dogs weighing 5, 20, and 40 kg.

Diet	Cost (US$), median (range)
Highly digestible
HCD (n = 2)	—
5-kg dog	2.30 (2.17–2.37)
20-kg dog	5.66 (5.43–6.06)
40-kg dog	9.33 (8.97–10.05)
CPD, dry (n = 4)	—
5-kg dog	0.91 (0.68–1.25)
20-kg dog	2.57 (1.92–3.54)
40-kg dog	4.32 (3.23–5.96)
CPD, canned (n = 4)	—
5-kg dog	3.32 (2.88–3.39)
20-kg dog	9.40 (8.16–9.60)
40-kg dog	15.81 (13.73–16.14)
Low-fat
HCD (n = 2)	—
5-kg dog	2.10 (1.44–2.77)
20-kg dog	5.53 (3.69–7.39)
40-kg dog	9.25 (6.21–12.32)
CPD, dry (n = 4)	—
5-kg dog	0.95 (0.73–1.43)
20-kg dog	2.68 (2.05–4.05)
40-kg dog	4.51 (3.46–6.82)
CPD, canned (n = 4)	—
5-kg dog	3.86 (0.73–1.43)
20-kg dog	10.94 (9.58–12.72)
40-kg dog	18.40 (16.12–21.38)
Novel or limited ingredient
HCD (n = 2)	—
5-kg dog	3.61 (2.93–4.29)
20-kg dog	9.34 (7.39–11.29)
40-kg dog	15.58 (12.27–18.89)
CPD, dry (n = 12)	—
5-kg dog	1.18 (0.85–1.71)
20-kg dog	3.35 (2.41–4.83)
40-kg dog	5.63 (4.06–8.12)
CPD, canned (n = 7)	—
5-kg dog	4.00 (3.48–4.31)
20-kg dog	11.33 (9.84–12.21)
40-kg dog	19.06 (16.55–20.54)
Hydrolyzed protein
HCD	—
5-kg dog	—a
20-kg dog	—a
40-kg dog	—a
CPD, dry (n = 8)	—
5-kg dog	1.04 (0.87–1.56)
20-kg dog	2.95 (2.47–4.43)
40-kg dog	4.96 (4.15–7.45)
CPD, canned (n = 4)	—
5-kg dog	4.34 (4.29–4.37)
20-kg dog	12.30 (12.14–12.38)
40-kg dog	20.69 (20.42–20.82)
Fiber-enriched
HCD	—
5-kg dog	—b
20-kg dog	—b
40-kg dog	—b
CPD, dry (n = 3)	—
5-kg dog	1.04 (0.79–1.39)
20-kg dog	2.93 (2.24–3.94)
40-kg dog	4.93 (3.76–6.62)
CPD, canned (n = 1)	—
5-kg dog	5.23 (5.23–5.23)
20-kg dog	14.81 (14.81–14.81)
40-kg dog	24.90 (24.90–24.90)
Ultralow-fat
HCD (n = 2)	—
5-kg dog	2.93 (1.74–4.02)
20-kg dog	8.12 (4.53–11.45)
40-kg dog	13.63 (7.65–19.2)
CPD, dry	—
5-kg dog	—c
20-kg dog	—c
40-kg dog	—c
CPD, canned	—
5-kg dog	—c
20-kg dog	—c
40-kg dog	—c

^a

Not possible to mimic hydrolyzed protein HCDs.

^b

Impractical to mimic fiber-enriched HCDs.

See Table 3.

^c

No ultralow-fat dry or canned CPDs commercially available.

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Median monthly costs (US$) per kilogram body weight of home-cooked diets (HCDs) and veterinary therapeutic commercially prepared diets (CPDs), dry and canned.

Citation: Journal of the American Veterinary Medical Association 260, S3; 10.2460/javma.22.07.0284

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Discussion

CCEs can be a daunting disease process to control in veterinary medicine; however, many dogs can be treated successfully with nutritional management, either as the sole therapy or in conjunction with medical management.^8,9 Clients are increasingly interested in feeding HCDs as an alternative to veterinary CPDs, sometimes because of a perceived cost savings. However, feeding an HCD is not more economical than feeding a dry CPD.

In our study, dry CPDs had a lower cost than canned CPDs and HCD formulations. This conclusion parallels what has been previously published for HCDs to manage other conditions.^13–16 Among the dry CPDs, there was a nearly 2-fold cost range within each diet type, with less variability observed in the costs of the canned diets. Given this wide range, it should be noted that the least expensive low-fat HCD cost less than the most expensive low-fat CPD. This was most likely a result of the low price of chicken breasts at the time this study was performed.

The increased cost of canned CPDs can likely be attributed to several factors, such as the higher cost to store and handle more perishable, raw materials compared to shelf-stable dried and rendered raw materials used more commonly in dry products. The different and additional packaging material used for canned versus dry pet foods could also affect the final cost of the product. In addition, the greater amount of water and heavier packaging material (ie, aluminum and steel) of canned diets may subsequently increase transportation costs that, in turn, affect consumer costs. It is also possible that some manufacturers have a greater profit margin or use third-party co-manufacturers, which increases their costs for canned versus dry CPDs.

The data illustrate that the majority of the cost of feeding HCDs is related to the prices of protein ingredients and multivitamin and multimineral supplement used. Our study used ingredient costs obtained from 3 large national grocery chains, but prices may vary depending on method of ingredient acquisition. For example, deer hunters may obtain venison meat for use in novel ingredient HCDs at a lesser expense than those purchasing from online or local game meat retailers. Ability to grow and harvest certain ingredients for oneself may also lessen total recipe cost. In addition, coupons, promotional sales, and bulk shopping can be used to acquire ingredients at a lower cost. Alternatively, the use of “premium” or organic ingredients may result in a greater overall recipe cost. Furthermore, some ingredients may not be readily available for purchase in certain grocery store locations. The amount of raw meat required to achieve the cooked amounts in the HCD recipes may be subject to mild variation. Nutrient loss or degradation through cooking varies by meat source as well as method of cooking. We attempted to account for this loss when estimating raw amounts of protein ingredients required for each recipe. The HCDs were formulated using cooked ingredient nutrient profiles, then we determined the amount of raw ingredients required to match the protein concentrations of the cooked versions.

The nutrient digestibility of different forms of chicken (ie, chicken meal, raw chicken, steamed chicken), and presumably other protein sources, varies, with steamed chicken having a greater amino acid digestibility than chicken meal.²¹ Thus, it is possible that HCDs could be formulated to be lower in protein relative to extruded and canned CPDs. This could, in turn, reduce the costs associated with protein content in HCDs; however, this concept is beyond the scope of our study and, based on the difference in digestibility, unlikely to have a major effect on cost.

Ultralow-fat diets (< 17 g fat/Mcal) are sometimes used in dogs with protein-losing enteropathy,^5–7,10 which requires using an HCD because there are no CPDs that provide such a low-fat concentration. There is a commonly prescribed diet among veterinary internists that has been coined the STP diet, consisting of sweet potato, tilapia, and pasta. We elected to formulate a complete and balanced version of this HCD for cost comparison as well as another ultralow-fat and novel ingredient diet consisting of shrimp and tapioca. It should be noted that ultralow-fat diets can be formulated with ingredients similar to those in the aforementioned low-fat HCDs, and this would decrease associated costs.

Although fiber is not considered an essential nutrient, dogs with CEs can exhibit a positive response to dietary fiber supplementation. The TDF concentrations of the HCDs consistently remained less than that of the CPDs. Various unfractionated carbohydrate-rich foods inherently provide a range of TDF concentrations. Among commonly used ingredients, rice and pasta are generally lowest in fiber, potatoes are moderate, and oats and barley are highest. Fruits and vegetables can also serve as a source of TDF, but not to the extent that fiber-enriched diets provide without increasing volume excessively.

It can be challenging to match the TDF concentrations of CPDs without adding multiple additional fiber sources (eg, cellulose, beet pulp, pea fiber, pecan shells), especially while maintaining palatability. To demonstrate this point, we used different fiber sources to modify the TDF of the low-fat chicken and white rice diet for a 20-kg dog eating its MER of 1,059 kcal/day. The results serve as a good reminder to veterinarians and clients that, in general, psyllium husk is a far more concentrated source of fiber than the commonly prescribed canned pumpkin. We compared only single sources of fiber for this subanalysis. The concept of fiber-responsive enteropathies is far beyond the scope of this discussion; it can be reviewed further elsewhere.¹¹ The supplements selected for the HCD formulations add a degree of variability to the cost because there is a multitude of supplements—both human supplements and those marketed for canine use—available commercially that can be selected based on a variety of reasons, including cost, availability, composition, and client and nutritionist preference. Furthermore, many dry CPDs may contain pre- and probiotics and other nutraceuticals within their formulations to improve intestinal health and provide additional benefits that are not always possible to include in HCDs and, if so, would increase the costs even more. It also remains to be determined which added nutraceuticals provide specific intestinal benefits versus appeal to consumers from a marketing standpoint.

Our study used a canine multivitamin, multimineral, and amino acid supplement (Balance It Canine, Balance It) given its widespread national use and nutritional profile that allows it to supplement easily commonly used ingredients for canine HCD recipes to provide complete and balanced nutrition. It is food grade and also currently meets the additional higher US federal and FDA inspection requirements for a human dietary supplement, which is one step below pharmaceuticals. This enabled the recipes to remain completely food grade, less the fish oil used, but a lower cost should be possible by using feed-grade supplements if available and appropriate. Regarding the methionine supplementation, only 2 HCD recipes (venison and potato, and rabbit and chickpea) required supplementation, and the cost of this supplement was slight ($0.01 to $0.06/100 kcal).

It is crucial to ensure that dogs’ micronutrient (ie, vitamin, mineral) needs are met when clients elect to feed HCDs. It has been demonstrated in several studies that most HCD recipes that clients use do not provide complete and balanced nutrition, most commonly resulting in deficiencies in micronutrients such as calcium, choline, selenium, and zinc.^22–24 Most clients will struggle to adhere to specific recipes in the long term;¹² thus, veterinarians must be sure to obtain and confirm accurate diet histories from clients who opt to feed their dogs HCDs.

Regarding the inclusion of fish oil, providing anti-inflammatory long-chain omega-3 fatty acids (eg, EPA and DHA) can reduce inflammation in the body by affecting leukocyte chemotaxis, adhesion molecule expression, and the production of pro-inflammatory cytokines.^25,26 There is conflicting evidence about the utility of supplemental EPA and DHA in people with intestinal disease,^27,28 and there are no peer-reviewed published data solely on the effects of fish oil supplementation in dogs with CEs. We elected to use fish oil in our HCD recipes to provide a ratio of LA + AA to EPA + DHA between 5:1 and 10:1 to reduce, hopefully, the production of more inflammatory mediators. Although adult dogs do not require long-chain omega-3 fatty acids in their diets per AAFCO nutrient profiles, the AAFCO does provide a maximum recommendation for the ratio of LA + AA + alpha-linolenic acid to EPA + DHA of 30:1. In addition, the National Research Council²⁹ does provide a recommended allowance of EPA and DHA for adult dogs (0.11 g/Mcal), which all HCDs exceeded.

If we look at the HCD in our study that included the most fish oil, it was the ground turkey and white rice diet for the 40-kg dog that called for 3⅜ teaspoons of canola oil and 2⅜ teaspoons of fish oil. This diet provided a LA + AA to EPA + DHA ratio of 6.4:1. If we adjust the ratio of canola oil to fish oil to provide a ratio of 27.2:1, maintaining the caloric density of the diet only by adjusting these oils, the HCD would subsequently call for 5⅛ teaspoons of canola oil and a ½ teaspoon of fish oil. This adjustment would decrease the cost from $0.51/100 kcal to $0.47/100 kcal. The impact of lower specific fatty acid ratios and resulting fish or marine oil supplementation on cost should be considered when formulating HCDs for CCEs.

When analyzing HCD cost, it is important to note that expenses associated with cooking (eg, water, energy, supplies), preparation time, and transportation were not considered in our study because these costs are difficult to calculate and are subject to significant variation. Likewise, clients who choose to feed HCDs may require additional refrigerator and/or freezer space for storing ingredients and meals, which adds an additional appliance cost along with the associated utility cost. Shipping and handling as well as taxes applied to supplement purchase were not included in this study.

Moreover, appointment expenses with board-certified veterinary nutritionists were not included in our analysis. Appointments with board-certified veterinary nutritionists are often a crucial first step when formulating HCDs because they possess the knowledge and training needed to ensure that each diet is complete and balanced, and they address the patients’ underlying disease processes. Furthermore, even if owners elect to feed CPDs, consultation with board-certified veterinary nutritionists should be considered for management of complicated CCEs.

Another limitation to consider is that prices of pet food and ingredients for HCDs are subject to inflation, and ingredients may be affected by limited availability. This has recently become quite transparent during an era affected by the coronavirus disease 2019 pandemic, and international conflicts and logistics disruptions. The results of our study may not remain true in several years’ time; thus, ongoing cost comparisons should be considered.

Last, a feeding option that has become increasingly promoted in the dog food marketplace is the provision of premade frozen formulations of dog food that look like HCDs, but are CPDs. Although it was not an aim of this study to evaluate this type of CPD specifically, some pet owners are reaching for this option for management of CCEs, because novel and limited ingredient and ultralow-fat diet options do exist. The cost to feed some of these premade frozen CPDs, on a US$/100 kcal basis (June 2022), ranges from $0.84 (turkey and whole-wheat macaroni diet) to $2.63 (venison, squash, and sweet potato diet). Relative to the costs of other options provided, these options will greatly exceed the cost of dry CPDs and will be similar or more expensive in cost to feeding HCDs.

A final consideration in interpretation of this study is that cost, like many other things, is relative to consumers. For some clients, paying a premium price to feed HCDs is worth the increased cost. The time spent preparing the dog’s meals may affect the human–animal bond positively. Veterinarians advising clients should understand these factors when discussing management strategies for CCEs to have a positive impact on client compliance.

Supplementary Materials

Supplementary materials are posted online at the journal website: avmajournals.avma.org