A comparison of the clinical manifestations of feeding whole and hydrolysed chicken to dogs with hypersensitivity to the native protein

An open-label clinical trial to evaluate the efficacy of an elemental diet for the diagnosis of adverse food reactions in dogs

BACKGROUND

The diagnosis of cutaneous adverse food reactions (CAFR) in dogs is dependent on a diet trial and provocative challenge.

HYPOTHESIS/OBJECTIVES

To evaluate the efficacy of an elemental diet for the diagnosis of CAFR in dogs.

ANIMALS

Sixty-two client-owned nonseasonally pruritic dogs.

MATERIALS AND METHODS

A prospective, uncontrolled, observational elimination diet trial study. Dogs were fed a commercially available elemental canine diet (Pro Plan Veterinary Diets EL Elemental Canine Formula, Nestlé Purina PetCare Company) for up to eight weeks. Pruritus was assessed using a validated Visual Analog Scale (PVAS), lesions with the Canine Atopic Dermatitis and Severity Index, 4th iteration (CADESI-04) and gastrointestinal (GI) signs with a client questionnaire. All dogs were challenged with their previous diet for up to 14 days. Treats were added from Day (D)7 to D14.

RESULTS

Forty-five dogs completed the study. Eighteen (40%) of these were diagnosed with CAFR and 27 (60%) were diet-nonresponsive (NR). Dogs with CAFR flared on provocative challenges within 14 days. The smallest volume of previous diet that induced a CAFR flare was one teaspoon in two dogs (11.1%). The mean number of days leading to a provocation of clinical signs was 4.88 days. Gastrointestinal signs improved in both groups. Eight of the dogs with CAFR (44.4%) were subsequently maintained on the elemental diet alone.

CONCLUSION AND CLINICAL RELEVANCE

Pro Plan Veterinary Diets EL Elemental Canine Formula is efficacious for the diagnosis of canine CAFR. One teaspoon of the offending diet may induce clinical signs in some dogs with CAFR.

Detection of chicken DNA in commercial dog foods

BACKGROUND

These days the number of potential food allergens is very large, but chicken is one of the most common allergens in dogs. Elimination diet is one of the clinical tools for the diagnosis of allergies and allergy tests are not very reliable. The restriction diet is most commonly carried out by feeding pet foods, relying on the ingredients on the label to select an elimination diet not containing previously eaten foods. Unfortunately, mislabeling of pet food is quite common. The purpose of this study was to determine the absence or presence of chicken DNA using both qualitative and quantitative polymerase chain reaction (PCR) analysis methods in dry and wet maintenance complete pet foods for adult dogs. Results were used to verify the declared composition on the labels.

RESULTS

Eleven out of fifteen (73%) dog foods were produced as declared by the manufacturer, two of which showed the presence of chicken protein as stated on the label. The remaining nine foods contained amounts of chicken DNA below 1%, consistent with declarations that no chicken was added in the composition. Four of tested dog foods (27%) were not produced consistently with the declaration on the packaging. Two dog foods (one dry and one wet) did not contain the claimed chicken protein. In two foods the addition of chicken DNA was detected at the level of over 2% and almost 6%, respectively.

CONCLUSIONS

In this study, we focused on one of the most commonly undeclared animal species on the label-chicken protein-and performed DNA analyzes to investigate possible contamination and mislabeling. The results showed some inaccuracies. However, most of them are trace amounts below 1%, which proves compliance with the label. Our results showed that undeclared animal species can be as common as missing an animal protein declared on the label. The conducted research indicates that both dry and wet analyzed foods should not be recommended as a diagnostic tool in elimination tests, because it may result in false negative results. Over-the-counter maintenance foods for dogs should not be recommended for the diagnosis and treatment of food hypersensitivity.

Cross-contamination in canine and feline dietetic limited-antigen wet diets

Background

Adverse food reactions (AFRs) are defined as abnormal responses to an ingested food or food additive. Diagnosis and treatment of AFRs consist of the complete elimination of these ingredients in the dietary trial. Previous studies have demonstrated the presence of undeclared ingredients in commercial limited-antigen dry food diets that can compromise the results and efficacy of dietary elimination trails. The aim of this study was to assess a selection of commercial canine and feline dietetic limited-antigen wet foods for the potential cross-contamination of animal proteins from origins not mentioned on the label.

Results

Eleven canine and feline dietetic limited-antigen wet foods (9 novel animal protein foods, 1 vegetarian and 1 hydrolyzed) were analyzed by polymerase chain reaction (PCR) to detect the presence DNA of animal and vegetal origins. PCR analysis confirmed the contamination of 6 of the 11 (54.5%) limited-antigen wet diets with undeclared animal protein. One of these 6 diets was solely composed of animal protein sources completely unrelated to those declared on the label. None of the foods containing horse meat or fish were contaminated, and neither were the vegetarian or the hydrolyzed food products. Moreover, the results show that had zoological class primers only been used to check for cross-class contaminations, as are generally used in the pet food industry for in-house checks, the apparent contamination rate would have been significantly underestimated: less than 20% (3/11), instead of the actual rate of 54.7% using species-specific primers.

Conclusion

This study reveals a high rate of cross-contamination in dietetic limited-antigen wet canine and feline foods, as previously described for dietetic dry limited-antigen foods (reported to be more than 80%). These results add new fuel to the discussion about the potential causes underlying the failure of elimination diets, since animal protein contaminants may actually be present in the commercial dietetic limited-antigen diets. AFRs may therefore occur as a result of inadequate practices in the pet food industry.

Comparing immediate-type food allergy in humans and companion animals-revealing unmet needs

Adverse food reactions occur in human as well as veterinary patients. Systematic comparison may lead to improved recommendations for prevention and treatment in both. In this position paper, we summarize the current knowledge on immediate-type food allergy vs other food adverse reactions in companion animals, and compare this to the human situation. While the prevalence of food allergy in humans has been well studied for some allergens, this remains to be investigated for animal patients, where owner-reported as well as veterinarian-diagnosed food adverse reactions are on the increase. The characteristics of the disease in humans vs dogs, cats, and horses are most often caused by similar, but sometimes species-dependent different pathophysiological mechanisms, prompting the specific clinical symptoms, diagnoses, and treatments. Furthermore, little is known about the allergen molecules causative for type I food allergy in animals, which, like in human patients, could represent predictive biomarkers for risk evaluation. The definite diagnosis of food allergy relies-as in humans-on elimination diet and provocation tests. Besides allergen avoidance in daily practice, novel treatment options and tolerization strategies are underway. Taken together, numerous knowledge gaps were identified in veterinary food allergy, which need to be filled by systematic comparative studies.