Quality control for hydrolyzed diets for cats and dogs

Adverse Food Reactions (AFR) in dogs and cats are a not-uncommon cause of dermatological signs presented in clinical practice. Commercial AFR diets are often used in both the diagnosis (via an elimination trial) and treatment of the condition, and two broad categories of diets are available:

1. “Selected“ or “novel“ protein diets, with limited protein sources and – ideally – a single carbohydrate source.

2. “Hydrolyzed diets“, consisting of partially or extensively hydrolyzed protein.

Elimination diet trials can be subject to various potential failures. Two major concerns are that the AFR diet must be free of ancillary proteins (as potential cross-contamination in petfood factories is a major concern) and (for hydrolyzed diets) have a guaranteed level of hydrolysis, with no remaining allergenic fragments present. Recent studies have highlighted that some commercial (mostly “over-the-counter”) diets marketed for AFR contain undeclared ingredients and/or large molecular weight proteins; for instance, discrepancies were found between protein analyses and labeling in around 75% of diets tested in recent studies 1 2 3. Consequently, to ensure the absence of cross-contaminated products, three key elements are required: fully characterized raw materials, fit-for-purpose industrial equipment and cleaning processes, and optimal analytical controls.

A recent study sought to confirm the specific protein composition of Royal Canin’s Anallergenic canine and feline diets (Ultamino in North America) – which are based on extensively hydrolyzed poultry feather and cornstarch – and the efficacy of the cross-contamination risk management process.

• Protein composition was assessed via high-sensitivity chromatographic, electrophoretic and proteomic techniques by an external independent laboratory. The results obtained confirmed the extensive level of protein hydrolysis (Figure 1), the absence of protein in the palatability enhancers (included in the kibble coating), and the absence of cross-contamination 4. The ubiquitous corn starch glycoprotein GBSS (granule-bound starch synthase) was detected, which to date has no known adverse effects in pets, but lipo-transfer proteins (LTPs) – which are well-recognized to be allergenic – were not detected. The same results were obtained for both canine and feline diets 4.

• Cross-contamination risks are assessed by testing each production batch using a specific 3-step DNA-based analysis (Figure 2). This involves measurement of the total DNA content of the diet and comparing the results with a conformity threshold established during a multicenter pre-clinical trial 5. If DNA is detected above this threshold, PCR analyses are conducted to identify the contamination source. To correlate the DNA to the unwanted proteins, “calibration curves” are then employed to assess the actual concentrations of protein present.

Since launching in 2011, this method has been employed to test more than 2,500 production batches of Anallergenic, with all found to conform to the required standards. This has allowed the batches to be released from the factory for sale6 7 8.

Acknowledgements to Mars Petcare Central Laboratory, Aimargues (France) and the Luxembourg Institute of Science and Technology.

Because of the strict quality control features (careful selection of raw materials, scrupulous factory protocols and cleaning methods, and rigorous DNA tests), no cross-contamination is present in these diets which, along with proven extensive protein hydrolysis, ensures optimal clinical reliability and efficacy for using Anallergenic in AFR diagnosis and management.