How it started

Dry pet food was first created in the late 1800s and is still a popular choice amongst many pet owners to this day, but with the advancement of current day technology, there is now a plethora of diets and food types available for our dogs and cats. These range from dry extruded and oven-baked food to fresh and raw food diets (and more).

A survey displayed how pet owner feeding practices changed between 2008 and 2018. The survey showed that feeding pets commercial extruded diets was still the predominant diet choice. However, there were more owners feeding their pets unconventional diets, such as raw, homemade or vegetarian foods, than in previous studies investigating diet choice.1

In this blog, we’ll discuss some of the differences between extruded, fresh and raw diets but let’s first define what we mean by each of these categories:

Raw diets encompass a wide variety of formats ranging from incomplete, unprocessed (with no sterilization steps) to complete and balanced diets, which include sterilization steps.2

Dry kibble diets made by extrusion. Extrusion is a process which uses heat, pressure and moisture to cook the pet food.3

Fresh diets are processed at lower temperatures and pressures and usually include a sterilization step. 

Current research shows some possible benefits and risks to feeding these different diets to our pets, which range from nutrient digestibility to food safety to sustainability.

There are many factors to consider when comparing different types of diets, regardless of the format. It's important to note that any of these diets could be appropriate for your pet as long as they are complete, balanced and meet all of your pet’s nutritional needs.

If you're ever unsure about a diet’s nutritional adequacy, here are some tips to better understand how to proceed:

•   Always be sure to check for a nutritional adequacy statement (i.e. formulated to meet or exceed AAFCO or FEDIAF requirements for dogs or cats at maintenance, all life stages, or growth & reproduction).

o   Companies which share typical analysis reports on each of their diets is an even better indicator to know their diets are meeting those requirements.  

•   Look into the companies’ credentials, team, manufacturing process, and ingredients. Check out how they test their diets nutritional efficacy and food safety.

 Speak to your vet. They can be a good resource when choosing a new diet for your pet.

Nutrition Considerations

Some evidence shows that raw and fresh diets are slightly more digestible than dry kibble diets4–7, but it is important to note that all diets investigated in these studies, including the dry kibble diets, were highly digestible and exceeded digestibility standards (greater than 80% for protein and greater than 90% for fat). There are several possible reasons as to why the raw and especially fresh diets were more digestible than the kibble diets in those studies. An animal’s age, diet composition, source and form of ingredients, and processing methods can impact digestibility. In addition, some of the experiments in these studies did not choose diets formulated with the same nutrient and energy concentrations which can impact results and conclusions.6 One study had a greater amount of fiber in the extruded diet which could be lowering the reported digestibility in this diet. All of these listed reasons can contribute to the studies’ reported higher digestibilities of raw and fresh diets and lower digestibility of extruded diets. It is also important to consider the notably higher protein and fat content found in raw and fresh diets when reviewing this data.7  If a minimally processed diet contains plant-based ingredients like pulses (for example, chickpeas or lentils), this can reduce nutrient digestibility, as these ingredients require processing to increase the protein availability.8  Extrusion is often used to improve protein and starch digestibility in pet foods, but it can reduce heat-sensitive vitamins.3 Manufacturers often remedy this by calculating losses that occur during extrusion and compensating for those losses in formulation.

Food Safety Considerations

The benefit of extruded and commercial fresh diets over raw diets is the processing/cooking step. Not only is heat cooking known to increase nutrient and calorie digestibilities in diets for humans,9 this cooking step also adds in the critical “kill” step to minimize the risk of microbial contamination these diets could have. Raw diets have potential zoonotic concerns when it comes to pathogen shedding because there is no heat treatment to kill/minimize those pathogens. Salmonella transmission from dogs to their owners via contaminated food has been observed in past studies. There is always the risk of Salmonella and other pathogens in any type of pet food, including dry kibble, however, there is a higher prevalence of Salmonella in raw diets vs processed dog and cat foods.10 Pathogen shedding also occurs more often in dogs fed a raw diet compared to dry kibble.11,12 Research shows that regular at-home cleaning and disinfection routines are ineffective at getting rid of Salmonella contamination from bowls,13 and even at a raw-feeding kennel with good daily cleaning routines, Salmonella was still present on surfaces.14 Raw and fresh foods also shouldn’t be left in your pet’s bowl for longer than an hour, and if any food happens to remain in their bowl, it needs to be thrown away, leading to increased food waste. 

Sustainability Considerations

Different factors can influence the sustainability of pet food, including ingredient choice, ingredient composition, digestibility, and ingredient inclusion. Ingredient choice is often made considering consumer demand instead of only nutritional composition, leading to choosing ingredients that compete directly with human diets. Additionally, diets are often formulated to contain an excess of nutrients to satisfy market demands instead of just nutritional demands. A recent study investigating the environmental impact of dry, wet and commercial homemade (fresh) diets in Brazil, found dry diets had the smallest environmental impact compared to wet and fresh diets. This study found that dry diets were utilizing plant-based ingredients more than wet or fresh diets which contributed to lower greenhouse gas emissions, land and water usage.15

Dry diets can last up to 18 months (unopened) in a cool, dry environment, and lasts up to six weeks once opened. Fresh and raw diets must be kept (and transported) in a fridge or freezer and can only be kept in your refrigerator for approximately a week, or  kept in a freezer for 6-12 months. Practical storage conditions and transportation energy are also important factors to consider when choosing a diet for your pet.

All in all, there are several factors to consider when deciding which diet is best for your dog, and with all the options out there today, it can be a difficult decision. Keeping in mind your pets’ nutrient requirements, cost of food, and food safety in your home are important. If you have immunocompromised family members, young children, or seniors in your home, choosing a cooked/processed diet may be a safer option for your household. 

A friendly reminder to wash your hands after handling any type of pet food, treat and even your dog and/or cat to maintain your hygiene. Keeping up with these important practices are going to keep you, your loved ones, and your furry companions happy and healthy! 

Unsure of Where to Start? Here are some tips!

At HOPE, we follow AAFCO and FEDIAF recommendations, and go above and beyond those recommendations by keeping up with current research and constantly reassessing our formulas to ensure our pets receive premium quality nutrition. Each batch of HOPE Pet Food is tested by a third-party laboratory to ensure all nutrients are present and no nasties (like Salmonella). HOPE’s formulas are also tested for digestibility to make sure they are delivering high quality and available nutrients to our pets. HOPE Pet food employs an in-house pet nutritionist available to answer questions about nutrition anytime

References

1.   Dodd, S. et al. An observational study of pet feeding practices and how these have changed between 2008 and 2018. Vet. Rec. 186, 1–9 (2020).
2.   Butowski, C. F., Moon, C. D., Thomas, D. G., Young, W. & Bermingham, E. N. The effects of raw-meat diets on the gastrointestinal microbiota of the cat and dog: a review. N. Z. Vet. J. 70, 1–9 (2022).
3.   Singh, S., Gamlath, S. & Wakeling, L. Nutritional aspects of food extrusion: A review. Int. J. Food Sci. Technol. 42, 916–929 (2007).
4.   Kerr, K. R., Vester Boler, B. M., Morris, C. L., Liu, K. J. & Swanson, K. S. Apparent total tract energy and macronutrient digestibility and fecal fermentative end-product concentrations of domestic cats fed extruded, raw beef-based, and cooked beef-based diets. J. Anim. Sci. 90, 515–522 (2012).
5.   Algya, K. M. et al. Apparent total-tract macronutrient digestibility, serum chemistry, urinalysis, and fecal characteristics, metabolites and microbiota of adult dogs fed extruded, mildly cooked, and raw diets. J. Anim. Sci. 96, 3670–3683 (2018).
6.   Beloshapka, A. N. et al. Fecal microbial communities of healthy adult dogs fed raw meat-based diets with or without inulin or yeast cell wall extracts as assessed by 454 pyrosequencing. FEMS Microbiol. Ecol. 84, 532–541 (2013).
7.   Tanprasertsuk, J., Perry, L. M., Tate, D. E., Honaker, R. W. & Shmalberg, J. Apparent total tract nutrient digestibility and metabolizable energy estimation in commercial fresh and extruded dry kibble dog foods. Transl. Anim. Sci. 5, 1–9 (2021).
8.   Cargo-froom, C., Shoveller, A., Marinangeli, C. P. F. & Columbus, D. A. Methods for Processing Pulses to Optimize Nutritional Functionality and Maximize Amino Acid Availability in Foods and Feeds. 65, (2020).
9.   Carmody, R. N. & Wrangham, R. W. The energetic significance of cooking. J. Hum. Evol. 57, 379–391 (2009).
10. Davies, R. H., Lawes, J. R. & Wales, A. D. Raw diets for dogs and cats: a review, with particular reference to microbiological hazards. J. Small Anim. Pract. 60, 329–339 (2019).
11. Olkkola, S. et al. Population genetics and antimicrobial susceptibility of canine campylobacter isolates collected before and after a raw feeding experiment. PLoS One 10, 1–15 (2015).
12. Runesvärd, E., Wikström, C., Fernström, L. L. & Hansson, I. Presence of pathogenic bacteria in faeces from dogs fed raw meat-based diets or dry kibble. Vet. Rec. 187, 1–6 (2020).
13. Weese, J. S. & Rousseau, J. Survival of Salmonella Copenhagen in food bowls following contanimation with experimentally inoculated raw meat: Effects of time, cleaning, and disinfection. Can. Vet. J. 47, 887–889 (2006).
14. Morley, P. S. et al. Evaluation of the association between feeding raw meat and Salmonella enterica infections at a Greyhound breeding facility. J. Am. Vet. Med. Assoc. 228, 1524–1532 (2006).
15. Pedrinelli, V., Teixeira, F. A., Queiroz, M. R. & Brunetto, M. A. Environmental impact of diets for dogs and cats. Sci. Rep. 1–12 (2022). doi:10.1038/s41598-022-22631-0