Pet parents today are contemplating questions about companion animal nutrition with a level of scrutiny that was uncommon even a decade ago. Many are reading ingredient labels, evaluating processing methods, and comparing the purported benefits of fresh, frozen, freeze-dried, and conventionally processed dry diets. As nutritional awareness in human medicine has grown, analogous concerns have migrated into the veterinary context, and clinicians are increasingly expected to respond to questions that their formal training may not have adequately prepared them to answer.
The challenge is not simply one of client communication. It reflects a genuine gap in veterinary education. Many practitioners learned to recommend pre-packaged therapeutic diets for specific disease states but received limited instruction in the broader science of nutrition. When clients ask whether relationships exist between artificial additives and cancer, inflammatory bowel disease, or obesity, the scientific literature does in fact offer relevant data. The problem is that most clinicians were not trained to engage with it. That gap is becoming increasingly difficult to justify as nutrition moves closer to the center of integrative veterinary practice.
The Rise of Ultra-Processed Foods and Their Relevance to Veterinary Medicine
The classification of ultra-processed foods, commonly abbreviated as UPFs, emerged from the NOVA food classification system developed by researchers at the University of São Paulo. UPFs are defined not by individual nutrients but by the degree and purpose of their processing. They are characterized by the inclusion of food substances with no or rare culinary use and by the presence of additives designed specifically to improve palatability, appearance, texture, or shelf stability in the finished product.
In human populations, the epidemiological evidence linking high UPF consumption to adverse health outcomes has grown substantially. A series of articles published in The Lancet concluded that the rise of UPFs in modern diets is damaging public health, fueling chronic non-communicable diseases worldwide, and deepening health inequalities. Research has documented strong associations between UPF consumption and increased risk of cancer, cardiovascular disease, type 2 diabetes mellitus, psychological conditions, and premature mortality. In the United Kingdom and United States, more than half of the average diet now consists of UPFs, and for some demographic groups the proportion reaches as high as eighty percent.
The parallel with companion animal diets is not incidental. Many of the same processing methods, ingredient categories, and additive classes present in human UPFs are used extensively in commercial pet food manufacturing. The scientific community is only beginning to rigorously examine whether similar associations between UPF consumption and disease risk exist in companion animals, but the mechanistic plausibility is sufficient to warrant serious clinical attention. The major pet food industry has already begun responding to consumer pressure, with large manufacturers actively pursuing fresh and gently cooked formulations. Veterinarians who are not conversant with the science behind these shifts will find themselves poorly positioned to guide their clients through an increasingly complex nutritional landscape.
Food Additives: Definitions and Functional Categories
A working definition of food additives in the veterinary context was provided by Roudebush, who described them as substances purposely incorporated into foods to provide desirable characteristics including color, flavor, texture, stability, or resistance to spoilage. An important conceptual distinction exists between additives broadly defined and preservatives specifically. Preservatives are a subset of additives whose function is to protect food against decay, discoloration, or spoilage under normal storage conditions. All preservatives are additives, but not all additives serve a preservative function. Clarity on this distinction is useful when evaluating ingredient lists and communicating with clients who may use these terms interchangeably.
The additive categories of greatest clinical and scientific interest include preservatives, flavor enhancers and palatability agents, emulsifying agents and stabilizers, and coloring compounds. Each category involves distinct mechanisms of action, regulatory histories, and bodies of research that are worth examining individually.
Preservatives: Antioxidants, Antimicrobials, and Emerging Concerns
Foods with high fat content are particularly vulnerable to oxidative degradation. When lipids are exposed to oxygen over time, they undergo rancidification, and the resulting lipid oxidation products can initiate side reactions with amino acids and fat-soluble vitamins that meaningfully reduce nutritional value. Antioxidant preservatives function by interrupting these oxidative chain reactions. Dry foods require higher antioxidant concentrations than wet foods due to their comparatively greater oxygen exposure during storage.
Antioxidant preservatives used in commercial pet foods over time have included citric acid, ascorbates, tocopherols, propyl gallate, tertiary butylhydroquinone, and the synthetic compounds butylated hydroxyanisole and butylated hydroxytoluene, referred to as BHA and BHT respectively. Consumer and scientific concern regarding BHA and BHT has centered on potential carcinogenicity, endocrine disruption, and possible hepatic and renal toxicity. A 2018 safety assessment by the European Food Safety Authority concluded that in limited quantities these compounds present no concern for consumer safety, while noting that for cats, a safe dose could not be established from available tolerance data, a qualification that deserves clinical attention given the species-specific metabolic vulnerabilities of feline patients.
Ethoxyquin presents a more complex regulatory picture. A metabolite of ethoxyquin has been identified as possibly genotoxic, and an associated impurity has been characterized as a possible mutagen. Clinical reports in dogs have described allergic reactions and pathological changes affecting the skin, liver, kidneys, thyroid, and reproductive system. The European Union prohibited ethoxyquin as a feed additive for all animal species in June 2020. It remains approved for use in animal feed in the United States under FDA Center for Veterinary Medicine oversight, a regulatory divergence that practitioners operating in an evidence-informed framework should be aware of when evaluating commercial diets.
Sulfite preservatives introduce an additional consideration. Sulfites can react with thiamine and convert it to thiamine disulfide, a poorly bioavailable form, creating a meaningful risk of thiamine deficiency in animals consuming diets where supplemental thiamine has not been added to compensate. In human subjects, sulfites have been associated with asthma, gastrointestinal disturbance, dermatitis, and urticaria, and there is no compelling reason to assume companion animals are categorically exempt from analogous responses.
The regulatory and safety history of humectants in moist pet foods is also instructive. Propylene glycol was widely incorporated as both an antimicrobial preservative and humectant in soft-moist pet foods and treats to reduce water activity and maintain texture. It has since been removed from the generally recognized as safe designation for use in cat food following documentation of its capacity to induce Heinz body anemia in felines at elevated doses, a reminder that regulatory approval at any given point in time does not constitute a permanent guarantee of safety.
Flavor Enhancers and the Engineering of Palatability
The palatability gap between dry kibble and moist pet foods presents a persistent challenge for manufacturers of dry diets. Animals strongly prefer moist foods, and a range of flavor-enhancing technologies have been developed to make dry formulations more acceptable. Acids such as phosphoric acid applied to the surface of kibble can enhance palatability, particularly in cats, though clinicians should be aware that high phosphorus loads from such applications carry risk for geriatric cats and those with pre-existing chronic kidney disease.
The most extensively used palatability tool in dry pet food manufacturing is animal digest. The production process involves controlled enzymatic degradation of animal tissues, most commonly ground poultry viscera, fish, liver, and beef lungs. Proteolytic enzymes, whether endogenous to the tissue or added externally, partially hydrolyze the protein content. The process is terminated through the application of heat and acid, typically phosphoric acid, which halts enzymatic activity and establishes a pH unfavorable to further degradation. The resulting liquid digest is then applied to the exterior of dry food at concentrations ranging from one to ten percent. Notably, different digest formulations are routinely used to support different flavor designations on product labels even when the underlying base ingredients are identical across those products.
A dimension of the animal digest question that warrants clinical consideration involves the source materials themselves. The FDA has documented the presence of pentobarbital in pet food ingredients derived from animals of terrestrial origin, raising the question of whether animals that received euthanasia drugs prior to death may contribute to the digest pool. This is not a hypothetical concern. FDA laboratory methods have confirmed the presence of pentobarbital in certain pet food ingredients, and practitioners should be prepared to address this when clients raise questions about ingredient sourcing.
Emulsifying Agents, Stabilizers, and Their Gastrointestinal Implications
Wet and gravy-based pet foods rely on polysaccharide gums and modified starches to prevent phase separation and maintain consistent product texture. The long-chain, high-molecular-weight polysaccharides in these compounds dissolve in water, elevate viscosity, and in some cases form gels. Gums used in commercial pet foods include alginates and carrageenan derived from seaweed, guar gum from leguminous seeds, gum arabic from tree exudates, xanthan gum of bacterial origin, and sodium carboxymethylcellulose, a chemically modified cellulose derivative.
Two of these compounds have attracted specific scientific concern. Guar gum has been found to impair protein digestibility in cats, with the effect more pronounced in senior animals, a finding with practical implications given the elevated protein requirements of aging feline patients. Carrageenan has been associated with intestinal inflammation and ulceration in experimental animal models, a body of evidence that has generated ongoing scientific and regulatory debate regarding its suitability as a food additive despite its widespread continued use.
Coloring Agents: Cosmetic Function and Emerging Toxicological Questions
Colorants in pet food serve a function directed primarily at the human purchaser rather than the animal consumer. Dogs and cats rely predominantly on olfaction and gustation rather than visual assessment when evaluating food, which means coloring additives offer no functional benefit to the animal itself. Coloring agents may be natural in origin, such as carotenoids, or synthetic, including iron oxide and coal tar derivatives. Synthetic dyes used in pet food products include tartrazine, sunset yellow, allura red, brilliant blue, and indigotine, compounds that correspond to FD&C yellow No. 5, yellow No. 6, red No. 40, blue No. 1, and blue No. 2 respectively.
Emerging research has begun to examine potential toxicological implications of synthetic food dyes beyond their cosmetic function. Experimental work has reported that Red 40, for example, induces DNA damage, promotes colonic inflammation, and adversely affects the gut microbiome in murine models. These findings have not yet been translated directly into companion animal clinical guidance, but they are consistent with a broader pattern of evidence suggesting that the cosmetic benefit of these additives should be weighed against their potential biological effects, particularly in animals consuming them in substantial quantities over the course of a lifetime.
The Significance of These Questions for Integrative Veterinary Practitioners
For clinicians practicing integrative veterinary medicine, nutrition occupies a position that cannot be separated from clinical outcomes in rehabilitation, pain management, acupuncture, or any other therapeutic domain. Diet exerts systemic influence on inflammatory status, metabolic function, immune competence, tissue repair, and long-term disease trajectory. Practitioners working across these disciplines routinely observe how dietary variables interact with treatment response, which means that a working knowledge of what commercial pet foods actually contain, and what the current evidence suggests about those ingredients, is not peripheral to clinical practice. It is central to it.
The clients arriving in integrative veterinary clinics today are frequently more informed about nutrition than those of a previous generation, and more skeptical of conventional approaches. Many have already transitioned their animals to fresh, raw, or homemade diets before presenting for an appointment. The practitioner’s role is not to reflexively endorse or dismiss these choices but to engage with them from a position of scientific literacy, evaluating available evidence while keeping both animal welfare and household safety within scope. That capacity requires familiarity with the mechanisms and research reviewed here, as well as a commitment to updating that knowledge as the science continues to develop.
Fresh and Minimally Processed Diets: Emerging Evidence
The scientific rationale for interest in fresh and minimally processed diets is grounded in part in the biochemistry of advanced glycation end products, or AGEs. AGEs form during high-temperature processing through non-enzymatic glycation reactions between reducing sugars and amino acids, producing the characteristic browning, color, and flavor associated with cooked food. Elevated AGE intake has been strongly associated in human research with type 2 diabetes mellitus, cardiovascular disease, obesity, atherosclerosis, systemic hypertension, neurodegenerative disease, and stroke. Research on companion animals has begun to explore whether these associations have analogous clinical relevance.
A study published in October 2025 examined serum metabolomics in senior dogs fed either a fresh, human-grade food or an extruded kibble diet over a one-year feeding period. Dogs in the fresh food group demonstrated metabolic changes consistent with ketosis, including alterations in branched-chain amino acid metabolism, increased fatty acid beta-oxidation, and elevated lipolysis. Serum concentrations of EPA and DHA were elevated in the fresh food group, attributable to the inclusion of chia seeds and salmon oil as dietary sources of ALA, supporting its function as a metabolic precursor to the longer-chain omega-3 fatty acids in dogs.
Serum AGE concentrations were decreased in the fresh food treatment group relative to controls. These metabolic adaptations were sustained across the full year-long observation period, suggesting physiological accommodation to a lower-carbohydrate, minimally processed dietary pattern rather than a transient response to dietary novelty. The authors identified implications for longevity and disease prevention as warranting further investigation.
Fresh diets are not without complications, however. Research from the University of Minnesota’s Minnesota Urolith Center recently identified a previously undescribed urinary stone type, calcium tartrate tetrahydrate, in dogs consuming fresh commercial pet food. Investigators identified choline bitartrate, a compound present in fresh dog food formulations and in supplements commonly recommended for dogs eating homemade diets to ensure nutritional completeness, as the likely causative agent. Several brands declined to disclose the specific form of choline bitartrate used in their formulations, leaving the precise risk profile incompletely characterized.
The findings were published in the May-June 2025 issue of the Journal of Veterinary Internal Medicine. This case illustrates an important principle: ingredients that are individually recognized as safe may produce unanticipated clinical consequences in the context of a broader dietary pattern, and the novelty of a food category does not guarantee its safety.
Raw Meat Diets: Evidence and Clinical Risks
Interest in raw meat-based diets reflects a philosophically coherent but practically complicated response to the limitations of highly processed commercial pet food. The risks associated with these diets are well-documented and require direct clinical engagement rather than dismissal or uncritical accommodation. Practitioners should be prepared to address the following concerns with specificity:
- Bacterial contamination, including potentially antimicrobial-resistant strains of Salmonella, Listeria monocytogenes, and Escherichia coli, presents risks to both the animal and the human household members handling the food
- Parasitic infection from organisms including Toxoplasma gondii, Trichinella spiralis, and various tapeworm species present in uncooked animal tissues
- Viral transmission, including H5N1 avian influenza, which the FDA has tracked in domestic cats and dogs in multiple states following consumption of contaminated unpasteurized or uncooked poultry and cattle products
- Nutritional imbalance, as homemade raw diets frequently fail to meet established nutritional standards, with documented deficiencies and excesses capable of producing pathological changes in bone development, organ function, and systemic metabolism, particularly in growing animals
- Physical injury associated with raw bone consumption, including dental fractures, esophageal and gastrointestinal foreign bodies, and mucosal irritation
- Zoonotic disease transmission to household members, with elevated risk for immunocompromised individuals, young children, and elderly adults
- Professional consensus against raw meat diets as expressed by the American Veterinary Medical Association and multiple public health agencies
Toward a More Rigorous Clinical Approach to Pet Nutrition
The available evidence does not support a simple hierarchical ranking of commercial, fresh, or raw diets as categorically superior or inferior. Each approach presents a distinct profile of benefits and risks that requires honest scientific evaluation. Highly processed commercial diets meet established nutritional standards but contain additive categories for which legitimate toxicological questions remain open. Fresh and minimally processed diets offer evidence of favorable metabolic effects but are not without their own emerging complications. Raw feeding reflects a biologically informed framework but carries infectious disease risks that extend beyond the individual patient to the household and potentially to clinical environments.
The practitioner’s responsibility in this context is not to follow nutritional trends or react to client preferences with reflexive reassurance. It is to engage with the scientific literature, communicate evidence accurately, and help clients make decisions that reflect the genuine state of knowledge rather than marketing narratives or online advocacy.
In an era when nutritional information spreads rapidly and unevenly through social media and consumer communities, the veterinary professional remains one of the few sources capable of providing guidance grounded in both scientific rigor and clinical experience. That capacity is especially important in integrative practice, where nutrition intersects with nearly every other dimension of patient care.