Donna Raditic, DVM, DACVN
Joe Bartges, DVM, PhD, DACVN, DACVIM
Calories consumed per day is the best common measure across all diets.
With so many brands and types of foods available (pet food sales exceed $24 billion in the United States, with Nestle Purina PetCare, Mars PetCare Inc, Big Heart Pet Brands, Hill’s Pet Nutrition, Diamond Pet Foods, and Blue Buffalo accounting for approximately 70% of the market), owners, veterinarians, and veterinary nurses can have difficulty interpreting ingredient labels, assessing the quality of diets, and understanding pet food regulations. As a result, members of the veterinary healthcare team may be reluctant to make specific recommendations.
Veterinary healthcare teams are familiar with recommending veterinary therapeutic diets (VTD) for management of chronic disease states, but many of these diets are suitable for adult maintenance and growth. VTD have accessible information on caloric and nutrient profiles, may address inflammation with specific nutrients, and have higher digestibility and less contamination than over-the-counter (OTC) diets.
Differences Between OTC Diets and VTD
The term “therapeutic diet” has no legal definition; however, the Food and Drug Administration has guidelines for the labeling and marketing of canine and feline diets intended to diagnose, cure, mitigate, treat, or prevent diseases (Box 1). These guidelines came about because such diets were historically distributed only through veterinarians; however, some of these diets are now available to consumers through Internet or store purchase with a veterinary prescription.
VTD are usually considered for managing specific medical conditions, such as kidney disease or osteoarthritis.1,2 Their ingredients and/or composition differ from OTC pet foods for a specific purpose, but this does not always preclude recommending these diets for healthy patients. Additionally, the quality control of their manufacture is often more stringent than that of OTC diets. Although some may carry statement reading “use under supervision of a veterinarian,” many VTD have AAFCO nutritional adequacy statements for adult and sometimes growth life stages (Table 1). For these reasons, we often recommend VTD for healthy pets to provide better nutrition and to aid in prevention of common disease states.
The Food and Drug Administration has guidelines for the labeling and marketing of canine and feline diets intended to diagnose, cure, mitigate, treat, or prevent diseases.
Benefits of VTD
VTD are formulated to assist in managing medical conditions based on known physiologic and nutritional differences between healthy individuals and those with a disease, or to contain nutrients that may have a functional role in managing a particular medical condition. For instance, VTD used for gastrointestinal (GI) disease are moderate in fat, calcium, and phosphorus. OTC diets often have more variable nutrient profiles and higher calcium:phosphorus ratios (Table 2).
VTD may also contain anti-inflammatory nutrients, as inflammation is a component of many disease states. Formulated with omega-3 fatty acids,3 antioxidants,4 and other special nutrients, these diets attempt to modulate inflammation in GI, dermatologic, orthopedic, and urologic disease states. Digestibility of VTD has also been reported to be higher than that of OTC diets, and according to ELISA testing, VTD are not contaminated with soy or with a protein source not listed on the label.5–7
When choosing diets to recommend for their patients, practitioners can access the complete nutrient profiles of VTD more easily than for many OTC diets. Caloric density in kcals/kg, kcals/cup, and kcals/can3 is available on websites and product guides; beginning in 2017, this information is required on all pet food labels. Caloric density is important in determining accurate feeding plans for pets at risk for becoming overweight/obese. Information regarding the use of VTD is also available from manufacturers and Diplomates of the American College of Veterinary Nutrition (ACVN), who routinely use VTD.
Prescribing VTD with known kcal/kg density along with exact feeding plans can be used to help prevent excess weight gain in at-risk pets.
The Pricing Difference
VTD are often perceived as expensive compared to OTC diets. Table 3 shows average costs of therapeutic and OTC diets, based on information obtained via the Internet. Compared with human food packaging, pet food bag and can sizes vary greatly. This variability makes it difficult to compare costs on a “per bag or can” basis. We determined the costs of both VTD and OTC diets on a per 100 kcal basis for comparison, because calories consumed per day is the best common measure across all diets. VTD can be competitively priced when compared per 100 kcal. We suggest, however, that comparisons be simplified across the pet food industry by employing common bag and can sizes.
Prevention, Not Just Treatment
It has been reported that >50% of the US pet population is overweight.8 Prescribing VTD with known kcal/kg density along with exact feeding plans can be used to help prevent excess weight gain in at-risk pets. We recommend owners use a gram scale for weighing canned and dry foods, similar to human weight management plans, to deliver exact daily caloric intake. This also allows precise intake adjustments as the pet grows, is neutered, and ages (Box 2).
We also use VTD, especially those formulated for GI disease, orthopedic disease, and adverse food reactions, for patients who are “at risk” for chronic disease states. For instance, we have used VTD in breeds of dogs at risk for developmental orthopedic disease, obesity, and immunologic adverse food reactions. We use VTD in cats at risk for obesity and urinary tract disease because of neutering and environmental conditions (eg, indoor versus outdoor, single cat versus multicat household).
As VTD have more similar, moderate, and complete and known nutrient profiles along with company support, we encourage practitioners to recommend these diets for adult maintenance and growth. In our opinion, better quality control, fatty acid balance, and reported higher digestibility of VTD make these diets better nutrition for pets.
Caloric density is important in determining accurate feeding plans for pets at risk for becoming overweight/obese.
- Polzin DJ. Evidence-based step-wise approach to managing chronic kidney disease in dogs and cats. J Vet Emerg Crit Care (San Antonio) 2013;23:205-215.
- Bartges JW, Budsberg SC, Pazak HE, et al. Effects of different n6:n3 fatty acid ratio diets on canine stifle osteoarthritis. Orthopedic Research Society 47th Annual Meeting 2001.
- Bauer JE. Therapeutic use of fish oils in companion animals. JAVMA 2011;239:1441-1451.
- Sparkes AH. Feeding old cats—an update on new nutritional therapies. Top Companion Anim Med 2011;26:37-42.
- Raditic DM, Remillard RL, Tater KC. ELISA testing for common food antigens in four dry dog foods used in dietary elimination trials. J Anim Physiol Anim Nutr (Berl) 2011;95:90-97.
- Willis-Mahn C, Remillard R, Tater K. ELISA testing for soy antigens in dry dog foods used in dietary elimination trials. JAAHA 2014;50:383-389.
- Parr JM, Remillard RL. Common confounders of dietary elimination trials contain the antigens soy, pork, and beef. JAAHA 2014;50:298-304.
- Larsen JA, Villaverde C. Scope of the problem and perception by owners and veterinarians. Vet Clin North Am Small Anim Pract 2016;46:761-772.
- Bartges JW, Kirk CA, Lauten S. Calculating a patient’s nutritional requirements. Vet Med 2004;99:632.
- Root MV, Johnston SD, Olson PN. Effect of prepuberal and postpuberal gonadectomy on heat production measured by indirect calorimetry in male and female domestic cats. Am J Vet Res 1996;57:371-374.
- Jeusette I, Daminet S, Nguyen P, et al. Effect of ovariectomy and ad libitum feeding on body composition, thyroid status, ghrelin and leptin plasma concentrations in female dogs. J Anim Physiol Anim Nutr (Berl) 2006;90:12-18.
- Bermingham EN, Thomas DG, Cave NJ, et al. Energy requirements of adult dogs: a meta-analysis. PLoS One 2014;9:e109681.
- Morrison R, Penpraze V, Greening R, et al. Correlates of objectively measured physical activity in dogs. Vet J 2014;199:263-267.