Diagnosis Of Adverse Food Reactions Research Articles

Establishment of clinical criteria for the diagnosis of adverse food reactions in dogs with atopic dermatitis.

Diagnosis of canine adverse food reactions (AFRs) is based on vague criteria, such as '>50% improvement' during elimination diet trial (EDT) followed by 'deterioration' during provocation test (PT). The objective of the study was to use predefined criteria to evaluate response during EDT [i.e., Owner Global Assessment of Treatment Efficacy (OGATE) = good-to-excellent] and relapse during PT [i.e., Owner Global Assessment of Challenge Deterioration (OGACD) = moderate-to-severe and/or >100% increase of lesional (Canine Atopic Dermatitis Extent and Severity Index, 4th iteration, CADESI-04) and/or of pruritus (pruritus Visual Analog Scale, PVAS) scores]. Twenty-nine dogs with atopic dermatitis. An extensively hydrolysed diet was fed to all dogs followed, in seven of 11 nonresponders, by a second home-made novel-protein EDT. Dogs responding to either EDT were challenged with their previous diet. Thirteen (44.8%) dogs were diagnosed with AFRs: at the end of EDT, their OGATE was good (9 of 13; 69.2%) or excellent (four of 13; 30.8%), and both CADESI-04 (46.7%) and PVAS (71.1%) had decreased significantly; at the end of PT, OGACD was moderate or severe in 12 of 13 (92.3%) dogs, and both CADESI-04 (127.9%) and PVAS (181.8%) had increased significantly. Of the 16 dogs without AFRs, 6 (37.5%) responded to the commercial (n = 5) or home-made (n = 1) diet [OGATE = good (three of six) or excellent (three of six)], with significant concurrent reduction of CADESI-04 and nonsignificant reduction of PVAS, yet they did not relapse during PT. The proposed (predefined) criteria for the evaluation of response during EDT and deterioration during PT seem reliable and are easily applicable in clinical practice and research.

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

The diagnosis of cutaneous adverse food reactions (CAFR) in dogs is dependent on a diet trial and provocative challenge. To evaluate the efficacy of an elemental diet for the diagnosis of CAFR in dogs. Sixty-two client-owned nonseasonally pruritic dogs. 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. 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. 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.

Assessment of adulteration in the composition of dog food based on DNA identification by real-time PCR

In a situation where the market of ready-made pet foods is the fastest growing in Europe, dog caregivers show some concerns about the use of ready-made products. Although pet food labels must be detailed and should inform about ingredients, mislabeling is an increasingly growing problem in the pet food industry. In an increasing number of studies, species undeclared by pet food producers are detected. This is especially important when using pet foods as an elimination diet in the diagnosis of adverse food reactions (AFR), as it interferes with the correct diagnosis. Therefore the aim of this study was to assess adulteration in the composition of complete commercial dry dog foods based on chicken DNA and pork DNA identification using the real-time PCR method. The study was conducted to determine whether dry over the counter foods (OTC) are a reliable alternative to veterinary therapeutic diets in the diagnosis and long-term therapy of AFR. The material consisted of 29 dry dog foods, some of which were labeled by the producers as hypoallergenic or mono-protein. Our research has shown that both mono-protein and hypoallergenic foods contain undeclared sources of animal proteins with lower economic value. In our study, 65 % of the dog foods contained undeclared chicken DNA, while 41 % – undeclared pork DNA. These results shown that both mono-protein and hypoallergenic dry dog foods should not be used in the diagnosis and long-term therapy of AFR in dogs with food allergies, as they may interfere with the effectiveness of the therapy, giving false negative results.

Combined prick and patch tests for diagnosis of food hypersensitivity in dogs with chronic pruritus.

Previous studies have shown that patch testing with food extracts can assist formulation of elimination diets (ED) in human patients with suspected adverse food reactions (AFR). Little is known about the use of these tests in dogs. To evaluate the effectiveness of a combination of prick and patch testing in current protocols, and food challenge (FC) tests in dogs with AFR. Prick and patch tests were performed on 21 dogs with chronic, nonseasonal pruritus. Dogs then were fed an ED formulated on the basis of the results. All dogs with improved clinical signs then were challenged with a food to which there had been a positive reaction in the tests. Six dogs subsequently were challenged with a food to which they had been negative on testing. Pruritus Visual Analog Scale (pVAS) and Canine Atopic Dermatitis Extent and Severity Index, 4th iteration (CADESI-04) were evaluated on Day (D)0, D30 and D60 of the ED. Sensitivity (SE), specificity (SP), positive (PPV) and negative (NPV) predictive values, and the Kappa (κ)value were calculated. Of the 21 dogs, there was a significant mean improvement in pVAS and CADESI-04 scores in 16 (76%) dogs after D30 (P < 0.01) and D60 (P < 0.01) of the ED. There were no statistical differences between D30 and D60. The combination of tests had SE, SP, PPV, NPV and κ values of 80%, 66.7%, 66.7%, 80% and -0.17, respectively. The combination of prick and patch testing reached high values of SE and NPV. A diagnosis of AFR was made in 76% of the dogs, and test results were useful for the selection of an ED.

An open label clinical trial to evaluate the utility of a hydrolysed fish and rice starch elimination diet for the diagnosis of adverse food reactions in dogs.

The diagnosis of adverse food reaction (AFR) is based on an eight week elimination diet (ED) and is confirmed by relapse upon re-challenge with the previously fed diet. Hydrolysed EDs are commonly used for this purpose. To evaluate a commercially available hydrolysed fish protein and rice starch ED for the diagnosis of AFR. Fifty nonseasonally pruritic dogs. Pruritus was assessed with a Visual Analog Scale, lesions with the Canine Atopic Dermatitis Lesions Index and quality of life with a validated questionnaire on days 0 and 56. Antimicrobial treatments were permitted during the first four weeks, and corticosteroids and oclacitinib during the first six weeks. Dogs showing at least 50% pruritus improvement were separately challenged with their prior diet, fish and rice. Thirty eight dogs completed the ED, four were dropped out due to worsening clinical signs, three to low palatability and five were lost to follow-up. In 24 dogs, pruritus improved by >50% and 22 underwent dietary challenges. Of these, 15 reacted to their prior diets and were diagnosed with AFR, whereas seven did not relapse (and a diagnosis of AFR was considered to be doubtful). Five dogs reacted to fish and four to rice. Of the 14 dogs in which pruritus did not improve, some underwent a second ED and others were successfully treated for atopic dermatitis. The hydrolysed fish and rice diet seemed to be a useful ED for the diagnosis of AFR, even in dogs allergic to fish or rice.

Undeclared animal species in dry and wet novel and hydrolyzed protein diets for dogs and cats detected by microarray analysis

BackgroundAlthough the European Pet Food Industry Federation (FEDIAF) stated that labels must be accurate and provide detailed information on the ingredients, mislabeling of pet food has been documented by several authors. This phenomenon is of particular concern when related to products used as elimination diets for the diagnosis of adverse food reaction (AFR) in dogs and cats because the presence of undeclared ingredients may negatively interfere with the trial and prevent the veterinarian from making an appropriate diagnosis. The aim of this study was to shed light upon the problem of contamination and mislabeling in both dry and wet novel protein diets (NPDs) and hydrolyzed protein diets (HPDs) using a microarray-based commercial kit which tests for the presence of 19 animal species.ResultsOf the 40 analyzed products (9 dry NPDs, 22 wet NPDs, 6 dry HPDs and 3 wet HPDs), ten presented a content that correctly matched the label, while five did not contain the declared animal species, twenty-three revealed the presence of undeclared animal species, and two had a vague label that did not allow the evaluation of its accuracy. The most frequently contaminants identified in both dry and wet pet foods were pork, chicken and turkey. The presence of undeclared animal species was higher in dry than wet pet foods; furthermore, a lower number of contaminating animal species was identified in HPDs than NPDs (4 vs 10), and a lower number of contaminated HPDs (6 out of 9, 67%) than contaminated NPDs was detected (24 out of 31, 77%). Thirteen out of 14 brands tested presented at least one mislabeled product.ConclusionsMislabeling seems to be a widespread issue in pet foods used as elimination diets. Contamination can occur in all types of products used for the purpose, although dry NPDs are the main issue. Due to the high risk of contamination, particular attention should be given to both the selection of raw material suppliers and the production process.

Qualitative and quantitative detection of chicken deoxyribonucleic acid (DNA) in dry dog foods.

Chicken is a common protein source in pet foods and is concurrently listed among food allergens. Commercial over-the-counter (OTC) diets with an alternative animal protein source are considered suitable for dietary elimination trials by pet owners. The potential presence of undeclared chicken-derived ingredients in these diets can compromise the outcome of the trial during the diagnosis of adverse food reactions. The aim of this study was to selectively verify the absence or presence of chicken DNA in 10 OTC dry canine foods, using qualitative and quantitative approaches. The method of identification of chicken-derived protein was elaborated with the polymerase chain reaction (PCR) technology, whereas quantitative real-time PCR was used for the quantitative assessment. In most of the analysed samples, the chicken DNA was detectable; however, the quantified amounts were predominantly low, although differences between batches were observed.

Critically appraised topic on adverse food reactions of companion animals (5): discrepancies between ingredients and labeling in commercial pet foods

BackgroundElimination dietary trials for the diagnosis of adverse food reactions (food allergies) in dogs and cats are often conducted with commercial pet foods while relying on their label to select those not containing previously-eaten ingredients. There are concerns that industrial pet foods might contain unlisted food sources that could negate the usefulness of performing food trials. Furthermore, unidentified ingredients might cause clinical reactions in patients hypersensitive to such items.ResultsWe searched two article databases on July 7, 2017 and January 12, 2018 for relevant articles, and we screened abstracts from the leading international veterinary dermatology congresses for suitable material. Additional citations were found in the selected papers. In all, we extracted data from 17 articles and one abstract. The studies varied both in the number of pet foods tested (median: 15; range: 1 to 210) and that of ingredients specifically evaluated (median: 4; range: 1 to 11). Studies most often employed either PCR to detect DNA or ELISA to identify proteins from one or more vegetal or animal species; two studies used mass spectrometry to increase the number of detectable proteins. The various methods found ingredients that were not on the label in 0 to 83% (median: 45%) of tested diets; this percentage varied between 33 and 83% in pet foods with “novel/limited” ingredients proposed for elimination diets. Similarly, ingredients were found to be missing from the label in 0 to 38% (median: 1%) of tested foods. Finally, six studies evaluated, among others, several hydrolysate-containing pet foods: mislabeling with unlabeled or missing ingredients was found only in one diet.ConclusionsThe mislabeling of pet foods appears rather common, even in those with “novel” or “limited” ingredients proposed for elimination diets. Unexpected added ingredients are more frequently detected than those missing from the label. There is insufficient information to determine if the presence of a contaminating component will lead to a clinical reaction in a patient allergic to it, as challenges with the mislabeled foods were not performed in dogs or cats allergic to such ingredients. The testing of hydrolysate-containing pet foods found only one instance of possible mislabeling.

Detection of DNA from undeclared animal species in commercial elimination diets for dogs using PCR.

Elimination diets are the gold standard for the diagnosis of adverse food reactions (AFR). A broad variety of commercial diets are available containing either hydrolysed protein or novel ingredients which claim to be suitable for elimination diets. Contamination may be one factor accounting for the failure of commercial elimination diet trials. To test commercial diets labelled as suitable for elimination diets for dogs, for DNA of animal origin other than that declared on the label. Twelve commercial dry and tinned dog food products were investigated for DNA of animal origin (chicken, turkey, beef, mutton and pork) using PCR testing. In nine of 10 over-the-counter diets, DNA of one or more animal species other than declared on the label was identified. The DNA most frequently detected was derived from beef (n = 8) and pork (n = 6). Two hydrolysed diets only contained DNA of the declared animal source. Over-the-counter "single protein diets" or canned meat products cannot be recommended for the diagnosis of dogs with AFR because contamination may cause the elimination diet to fail.

Identification of undeclared sources of animal origin in canine dry foods used in dietary elimination trials

Failure to respond to commercial limited antigen diets can occur in dogs kept on a dietary trial for the diagnosis of adverse food reaction (AFR). The aim of this study was to assess twelve canine dry limited antigen diets (eleven novel protein diets and one hydrolysed diet) for potential contamination by ingredients of animal origin not mentioned on the label. The validity of the two methods adopted for the detection of such food antigens was also evaluated. Each dietary product was analysed by microscopy analysis using the official method described in Commission Regulation EC 152/2009 with the aim of identifying bone fragments of different zoological classes (mammalian, avian and fish) and by polymerase chain reaction (PCR) for the identification of DNA of animal origin. Discrepancies between the results obtained by PCR and/or microscopy analysis and the ingredients listed on pet food packages were found. Only in two pet foods did the results of both analyses match the ingredients listed on the label. In the remaining ten samples, microscopy detected bone fragments from one or two unpredicted zoological classes, revealing avian fragments in six of ten samples followed by those of fish in five of ten and mammalian fragments in four of ten. In two samples, microscopy analysis identified a contamination that would have otherwise passed unobserved if only PCR had been used. However, PCR confirmed the presence of all the zoological classes detected by microscopy and also identified the DNA of an additional unexpected zoological class in two samples. Dogs might fail to respond to commercial limited antigen diets because such diets are contaminated with potential allergens. Both PCR and microscopy analysis are required to guarantee the absence of undeclared animal sources in pet foods. Before ruling out AFR, a novel protein home-made diet should be considered if the dog is unresponsive to a commercial regimen.

Variable Food-Specific IgG Antibody Levels in Healthy and Symptomatic Chinese Adults

BackgroundThe presence of food-specific IgG antibodies in human serum may be useful for diagnosis of adverse food reactions. However, the clinical utility of tesing for such antibodies remains very controversial. The aim of this study was to evaluate the serum levels and population distribution of food-specific IgGs and their association with chronic symptoms in a large-scale Chinese population.Methodology/Principal FindingsA total of 21305 adult participants from different regions of China had 14 type of food-specific serum IgG antibodies that were measured by enzyme-linked immunosorbent assay. Amongthese, 5,394 participants were randomly chosen to complete follow-up questionnaire surveys on their dietary characteristics and chronic symptoms. The concentrations of food-specific IgGs against 14 foods ranged from a median (interquartile range) of 7.3 (3.8, 12.6) U/mL of pork-specfic IgG to 42.3 (28.8, 60.2) U/mL of crab-specific IgG. The concentration of food-specific IgGs was closely related to gender; after adjustment for region and age, women had higher concentrations of food-specific IgGs against all of the 14 foods except chicken (regression coefficient (95% CI): 0.01 (−0.003, 0.023); P = 0.129) and corn (0.002 (−0.013, 0.016); P = 0.825). Similar results were also found in the relationship of geographic region to the food-specific IgG concentrations for the 14 foods. Chronic symptoms were negatively associated with the concentrations of a few food-specific IgGs, and were positively associated with the concentrations of other food-specific IgGs.ConclusionsThe levels of food-specific IgGs were variable both in healthy and in symptomatic Chinese adults. These findings raise awareness that demographic factors, the type of food and specific chronic symptoms should be considered before food elimination treatment based on IgG testing in patients with chronic symptoms is used in clinical practice.

Clinical Efficacy of a Novel Elimination Diet Composed of a Mixture of Amino Acids and Potatoes in Dogs with Non-Seasonal Pruritic Dermatitis

There has been a need for improvement of the elimination diet used for diagnosis of adverse food reaction (AFR) in dogs. Recently, a novel elimination diet composed of a mixture of amino acids and potatoes was developed. We evaluated the efficacy of the elimination diet for diagnosis of AFR in dogs. Twenty dogs that were suspected to have allergic dermatitis were enrolled in a 2-month food elimination trial using the diet. Before and after the trial, the clinical symptoms were evaluated based on the change in canine atopic dermatitis extent and severity index (CADESI), pruritus score and medication score. Of the 20 dogs, 15 completed the food elimination trial. The remaining 5 dogs were removed from the trial because of diet unpalatability, skin disease progression or diarrhea. On the basis of evaluation of the clinical scores, we observed that the clinical symptoms improved in 11 of the 15 dogs that completed the food elimination trial. Provocative challenge was performed in 10 of the 11 dogs that showed improvement in their clinical symptoms. Of the 10 dogs, 7 were diagnosed as having AFR against food ingredients such as pork, beef, chicken and wheat because their skin symptoms reappeared after intake of these ingredients. The results of the food elimination trial and the provocative challenge indicated the usefulness of the novel elimination diet for diagnosis of AFR.

Study of the chemical and nutritional characteristics of commercial dog foods used as elimination diet for the diagnosis of canine food allergy

ReferencesHypoallergenic” pet foods are commercial dietary products for dogs and cats used as elimination diets for the diagnosis of adverse food reactions. Aim of this study was to compare chemical and nutritional characteristics of this kind of dog foods with regular maintenance diets. Twenty-nine dry pet foods (pellets) were collected and divided into classes on the basis of the type (H: hypoallergenic; R: regular), source of fat (with or without fish oil) and source of protein (with or without fish protein) used in their composition. Labels of the H pet foods identified 8 products (44%) with one protein in their formula, suggesting that only few commercial manufacturers concern about the number of protein sources included in their products. Samples of the two groups showed different chemical profiles with lower levels of protein, gross energy, phosphorus and better fatty acid profile (expressed as % of total fatty acids) for H products in comparison to R foods: PUFA, 38.91 vs 24.03, P<0.01; ω3, 5.70 vs 2.58, P<0.01; ω6, 33.22 vs 21.63, P<0.01; DHA, 2.85 vs 0.16, P<0.05; CLA, 0.24 vs 0.08, P<0.05, for H and R respectively. This study suggests that the differences observed in the fatty acids composition may be attributed to fish proteins addition, but not to fish oil, in H pet foods production.

A retrospective analysis of case series using home‐prepared and chicken hydrolysate diets in the diagnosis of adverse food reactions in 181 pruritic dogs

The purpose of this retrospective study was to compare home-prepared and chicken hydrolysate diets in the diagnosis of canine adverse food reactions (AFR). Seventy-two dogs were fed home-prepared diets and 109 were fed hydrolysate. Owners chose the type of diet at presentation, and ingredients of home-prepared diets were selected depending on each dog's dietary history. Ectoparasitic infestations and microbial infections were treated during the trials. Cutaneous and gastrointestinal signs and pruritus scores were recorded before starting the diet, 6 weeks into the trials and after provocation with the original diets. AFR was diagnosed if pruritus resolved during the trial and recurred on dietary provocation. The dropout rate was lower for home-prepared diets although not statistically significant (18.1% home prepared; 24.7% hydrolysate, P=0.377). AFR alone was diagnosed in 10 dogs (17%) using home-prepared diets and in 15 (18.3%) fed the hydrolysate. Gastrointestinal problems were more frequent in dogs with AFR than in dogs without AFR (P=0.001). Another 11 dogs (18.6%) in the home-prepared diet group and 20 (24.4%) in the hydrolysate diet group had AFR concurrent with other pruritic diseases, mainly atopy. The similar frequencies of AFR diagnosis in the two groups (P=0.837 AFR; P=0.416 concurrent AFR) indicate that the chicken hydrolysate diet may be a valuable alternative to home-prepared diets in the diagnosis of canine AFR. Prospective cross-over studies are warranted to confirm these findings.

Diagnostic techniques in dermatology: The investigation and diagnosis of adverse food reactions in dogs and cats

Most veterinary clinicians recognize a population of patients in which dermatologic and/or gastrointestinal signs are related to the feeding of particular dietary components. This article briefly reviews the clinical signs associated with adverse food reactions in dogs and cats, and discusses the practical issues associated with confirming a diagnosis.

Food Allergies and Other Adverse Reactions to Foods

Adverse reactions to foods do occur. Their true degree of prevalence remains unknown. Many mechanisms are involved, including events at the gut mucosa surface, immunologic pathways, and nonimmunologic and possibly genetic influences, not all of which have yet been well studied. The major manifestations of food allergy have been cutaneous, gastrointestinal, and pulmonary. Others are less convincingly established. Of particular interest is the likelihood that certain rheumatic symptoms may be related to food sensitivity. Establishing a diagnosis of adverse food reaction requires thoughtful clinical evaluation and laboratory testing, confirmatory immunologic studies, and double-blind food challenge. Skin testing is a valuable screening tool and can help direct the physician to those patients for whom double-blind food challenge may be indicated. The simplest therapy is avoidance of foods to which an individual is sensitive. Sodium cromoglycate, antihistamines, prostaglandin synthetase inhibitors, and steroids have been used, but their efficacy has not yet been carefully evaluated.