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

Pre-illness dietary risk factors in dogs with chronic enteropathy

BACKGROUND

Dietary factors have been extensively studied as potential triggers of inflammatory bowel disease in humans. Scant literature exists regarding diet as a pre-illness risk factor in dogs with chronic enteropathy (CE).

HYPOTHESIS

To evaluate possible pre-illness dietary risk factors in dogs with CE.

ANIMALS

Ninety-five client-owned dogs; 48 with CE (25 presumptive and 23 confirmed) and 47 without a history of signs of gastrointestinal disease.

METHODS

Retrospective case-control questionnaire-based study at a veterinary referral teaching hospital in the United Kingdom. Diet history was obtained relating to the onset of initial presenting signs for all dogs. The main diet consumed underwent ingredient analysis and caloric distribution calculation using a guaranteed analysis convertor software. Length of time the main diet was fed and adherence to the World Small Animal Veterinary Association Global Nutrition Committee guidelines was also recorded.

RESULTS

The frequency of the main diet containing no carbohydrate was greater for controls (5/47 dogs, 11%) vs the combined presumptive and confirmed CE dogs (0/48 dogs, 0%; P = .05). Fewer dogs with confirmed CE were fed a main diet containing red meat as the primary protein source (2/23 dogs, 9%) vs controls (15/47 dogs, 32%; P = .03). A main diet moisture percentage of ≤14% as fed was significantly associated with confirmed CE in logistic regression analysis (OR 5.71 [95% CI: 1.18-27.69]; P = .03).

CONCLUSIONS AND CLINICAL IMPORTANCE

The presence of dietary carbohydrate, protein source, and dietary moisture content, or factors related to moisture content such as preservatives, might play a role as potential pre-illness dietary risk factors in dogs with CE.

Randomized controlled trial of hydrolyzed fish diets in dogs with chronic enteropathy

BACKGROUND

The role of diet in the pathogenesis and treatment of chronic enteropathies (CE) in dogs is unresolved.

OBJECTIVES

To compare the ability of diets composed of hydrolyzed fish, rice starch, and fish oil without (HF) or with prebiotics, turmeric, and high cobalamin (HF+) against a limited ingredient diet containing mixed nonhydrolyzed antigens and oils (control) to resolve clinical signs and maintain serum cobalamin and folate concentrations in dogs with nonprotein losing CE (non-PLE). To determine the ability of hydrolyzed fish diets to support recovery and remission in dogs with PLE.

ANIMALS

Thirty-one client-owned dogs with CE: 23 non-PLE, 8 PLE.

METHODS

Randomized, blinded, controlled trial. Diets were fed for 2 weeks; responders continued for 12 weeks. Nonresponders were crossed over to another diet for 12 weeks. Response was determined by standardized clinical evaluation with long-term follow-up at 26 weeks. Concurrent medications were allowed in PLE.

RESULTS

Nineteen of 23 (83%; 95% confidence interval [CI], 60%-94%) non-PLE CE responded clinically to their initial diet, with no difference between diets (P > .05). Four nonresponders responded to another diet, with sustained remission of 18/18 (100%; 95%CI, 78%-100%) at 26 weeks. Serum cobalamin concentration was increased (P < .05) and maintained by diet. Serum folate concentration decreased posttreatment (P < .05) but was restored by dietary supplementation. Hydrolyzed fish diets supported weight gain, serum albumin concentration, and recovery (P < .05) in dogs with PLE.

CONCLUSIONS AND CLINICAL IMPORTANCE

Changing diet, independent of antigen restriction or supplemental ingredients, induced long-term remission in dogs with non-PLE CE. Serum cobalamin and folate concentrations were maintained by diet. Hydrolyzed fish diets supported clinical recovery and remission in PLE.

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.

Determination of Mammalian Deoxyribonucleic Acid in Commercial Canine Treats and Supplements

Feeding an elimination diet exclusively is currently the only accurate diagnostic test for an adverse food reaction in dogs and cats. However, owner compliance has been identified as a challenge, and the inability to limit exposure to other items (including treats and supplements) is a remarkable reason for failure. The objective of the current study was to evaluate the presence of declared and undeclared mammalian deoxyribonucleic acid (DNA) in commercially available canine treats and supplements using polymerase chain reaction methodology. Eight treat products and 20 supplement products were analyzed for the DNA of 10 mammalian species (bison, cat, cow, dog, goat, horse, mouse, rat, pig, and sheep). The results showed that 88% (7/8) of treats and 40% (8/20) of supplements were found to contain at least one source of undeclared mammalian DNA. Undeclared pig and cow DNA were the most frequently identified, and there were only two instances of negative results for declared species. Because of the frequent finding of undeclared mammalian DNA in the assessed products, avoiding using treats and supplements during elimination trials is recommended.

What is in commercial cat and dog food? The case for mercury and ingredient testing

Commercial pet foods should be safe for long-term feeding. However, recent recalls and lawsuits have eroded public trust in pet food companies and products. Recent studies have identified high concentrations of mercury, a potent neurotoxin, in pet food products. Here we posit that pet food products require independent testing to verify safety and compliance with developed Food and Drug Administration and Association of American Feed Control Officials standards, and initiate a discussion as to why including quantification of mercury and methylmercury, as well as the identification of adulteration, are important to such testing protocols. The outcomes of these discussions will be multi-faceted: initiating the impetus to investigate the quality and label accuracy of pet foods; ensuring product safety; promoting transparency within the pet food industry; informing veterinary practices regarding pet food recommendations; providing data for evidence-based policy and regulatory enforcement; and working toward fulfilling the National Research Council's call for research that identifies levels of contaminants in animal feeds and residues in human foods.

Determination of mammalian DNA in commercial canine diets with uncommon and limited ingredients

Over‐the‐counter (OTC) limited ingredient canine diets could be reliable alternatives to veterinary therapeutic formulations for the diagnosis and management of adverse food reaction (AFR). However, the possibility of undeclared ingredients jeopardizes the efficacious use of OTC options for medical purposes. The objective was to determine the presence of undeclared ingredients in OTC canine dry diets marketed as limited or single protein source diets. Twenty‐one OTC adult canine diets marketed as limited or single protein source diets were purchased. Multiplex PCR was used to screen for DNA of 10 mammalian species with species‐specific primers that anneal to regions of the mitochondrial cytochrome b gene. The presence of DNA from one or more species not declared on the label was identified in all 21 diets: cow (Bos taurus), pig (Sus scrofa), sheep (Ovis sp.), goat (Capra hircus) and bison (Bison bison). Twenty diets were positive for the declared protein source and one diet was negative for the declared species. Cat (Felis catus), dog (Canis sp.), horse (Equus sp.), mouse (Mus musculus) and rat (Rattus norvegicus) DNA was not identified in any samples. The presence of undeclared mammal species in OTC canine dry diets marketed as having limited or single protein source ingredients may complicate AFR diagnosis and treatment. However, PCR can detect a miniscule amount of DNA which might not be clinically significant, because the amount needed to elicit a response is unknown. Quantification of the contamination was not determined in this study, precluding discrimination of intentional adulteration from unavoidable cross‐contamination.

Effect of an extruded animal protein-free diet on fecal microbiota of dogs with food-responsive enteropathy

Background

Dietary interventions are thought to modify gut microbial communities in healthy individuals. In dogs with chronic enteropathies, resolution of dysbiosis, along with remission of clinical signs, is expected with treatment.

Hypothesis/Objective

To evaluate changes in the fecal microbiota in dogs with food‐responsive chronic enteropathy (FRE) and in healthy control (HC) dogs before and after an elimination dietary trial with an animal protein‐free diet (APFD).

Animals

Dogs with FRE (n = 10) and HC (n = 14).

Methods

Dogs were fed the APFD for 60 days. Fecal microbiota was analyzed by Illumina 16S rRNA sequencing and quantitative polymerase chain reaction (PCR).

Results

A significantly lower bacterial alpha‐diversity was observed in dogs with FRE compared with HC dogs at baseline, and compared with FRE dogs after the trial. Distinct microbial communities were observed in dogs with FRE at baseline compared with HC dogs at baseline and compared with dogs with FRE after the trial. Microbial communities still were different in FRE dogs after the trial compared with HC dogs at baseline. In HC dogs, the fecal microbiota did not show a significant modification after administration of the APFD.

Conclusion and Clinical Importance

Our results suggest that, in FRE dogs, treatment with the APFD led to a partial recovery of the fecal microbiota by significantly increasing microbiota richness, which was significantly closer to a healthy microbiota after the treatment. In contrast, no changes were detected in the fecal microbiota of HC dogs fed the same APFD.

Atopic dermatitis in cats and dogs: a difficult disease for animals and owners

The purpose of this review article is to give an overview of atopic dermatitis in companion animals and of recent developments including knowledge on immunological background, novel treatment options and difficulties in disease management. The prevalence of hypersensitivities seems to be increasing. The pathogenetic mechanisms are not fully understood, yet multiple gene abnormalities and altered immunological processes are involved. In dogs and cats, the diagnosis of atopic dermatitis is based on history, clinical examination and exclusion of other differential diagnoses. Intradermal testing or testing for serum allergen-specific Immunoglobulin E is only used to identify allergens for inclusion in the extract for allergen immunotherapy. Symptomatic therapy includes glucocorticoids, ciclosporin, essential fatty acids and antihistamines. A selective janus kinase 1 inhibitor and a caninized monoclonal interleukin-31 antibody are the newest options for symptomatic treatment, although longterm effects still need to be assessed. The chronic and often severe nature of the disease, the costly diagnostic workup, frequent clinical flares and lifelong treatment are challenging for owners, pets and veterinarians. Patience and excellent communication skills are needed to achieve a good owner compliance and satisfactory clinical outcome for the animal.

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.

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

BACKGROUND

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.

OBJECTIVE

To evaluate a commercially available hydrolysed fish protein and rice starch ED for the diagnosis of AFR.

ANIMALS

Fifty nonseasonally pruritic dogs.

METHODS AND MATERIALS

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.

RESULTS

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.

CONCLUSION AND CLINICAL IMPORTANCE

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

Background

Although 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.

Results

Of 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.

Conclusions

Mislabeling 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.

DNA and Protein Analyses to Confirm the Absence of Cross-Contamination and Support the Clinical Reliability of Extensively Hydrolysed Diets for Adverse Food Reaction-Pets

Adverse food reactions (AFR) are a common cause of skin diseases in cats and dogs. The correct diagnosis and management of AFR relies upon clinical nutrition. The reliability of commercial hypoallergenic diets commonly used in AFR has been questioned because studies have shown the presence of proteins not declared on the label ingredients. It is proposed that extensively hydrolysed protein-based diets constitute a reliable nutritional solution. Royal Canin Anallergenic™ Canine and Feline diets are formulated with very low molecular weight feather protein and purified corn starch. Protein gel electrophoresis and thin layer paper chromatography were used to characterize protein hydrolysis in these diets and their hydrolysed raw materials; protein species were identified by mass spectrometry. To detect cross-contaminating protein, species-specific DNA was measured and correlated with ancillary protein content using calibration curves. The only protein components detected in the extensively hydrolysed feather protein raw material were amino acids and small oligopeptides. GBSS-I (Granule-bound starch synthase 1) was detected in the finished diets; this has not been reported as a clinically apparent allergen in dogs or cats. The DNA threshold corresponding to the maximum acceptable level of ancillary protein was not exceeded in 99.9% of more than 2150 product batches tested and no products were released to the market with cross-contaminating proteins. These results demonstrate the extensive level of protein hydrolysis in Royal Canin Anallergenic™ Canine and Feline diets and the absence of cross-contaminating protein, both key requirements for a diet to be used during diagnosis and for management of pets with AFR.

PCR analysis of a prescription vegetarian diet and use in three dogs with cutaneous adverse food reactions

BACKGROUND

Cutaneous adverse food reaction (CAFR) is diagnosed by performing an elimination diet trial utilizing prescription or home-cooked diets followed by provocative challenge.

OBJECTIVES

To report findings of PCR analysis of a prescription vegetarian diet (RCV) for undeclared proteins of animal origin, as well as to describe its utilization for diagnosis and management of dogs suspected of having CAFR.

ANIMALS

Three client-owned dogs.

METHODS

PCR analysis of RCV for 11 mammalian species and poultry. In three dogs, clinical examination, cytology, aerobic culture (if indicated) and at least one elimination diet trial with RCV.

RESULTS

In our case series, all dogs had a history of pruritus and recurrent pyoderma that resolved with infection control and an elimination diet trial. In cases 1 and 2, a diagnosis of CAFR was made following an elimination trial with RCV and provocative challenge. Case 3 had a previously confirmed diagnosis of CAFR and RCV was successfully used to maintain remission of CAFR-related signs. PCR testing of RCV was negative for 11 mammalian species and poultry.

CONCLUSIONS AND CLINICAL IMPORTANCE

The RCV diet was found not to contain any undeclared mammalian or avian proteins. In this case series, the RCV was successfully used to diagnose and maintain three dogs with CAFR.

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

Background

Elimination 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.

Results

We 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.

Conclusions

The 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.

Electronic supplementary material

The online version of this article (10.1186/s12917-018-1346-y) contains supplementary material, which is available to authorized users.

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.

Extensive protein hydrolyzation is indispensable to prevent IgE-mediated poultry allergen recognition in dogs and cats

Background

The central premise for the commercialization of diets with hydrolyzed ingredients is that the small-sized digested peptides would be unable to crosslink allergen-specific IgE at the surface of tissue mast cells and induce their degranulation. Evidence for the validity of this concept to diagnose food allergies in dogs and cats is limited, however. Our objectives were to study the recognition of standard and variably hydrolyzed poultry extracts by sera from dogs and cats with elevated chicken-specific serum IgE.

Results

Forty sera from dogs and 40 from cats with undetectable, low, medium or high serum levels of chicken-specific IgE were tested by ELISA on plates coated with the positive controls chicken, duck and turkey meat extracts and the negative controls beef meat (dogs) or wheat (cats). Plates were also coated with a non-hydrolyzed chicken meal, and mildly- or extensively-hydrolyzed poultry feather extracts. The frequencies of dogs with positive IgE against the various extracts were: chicken meat: 100%, duck and turkey meats: 97%, beef meat: 3%, non-hydrolyzed chicken meal: 73%, mildly-hydrolyzed poultry feathers: 37% and extensively-hydrolyzed poultry feathers: 0%. For cats, these respective percentages were (with wheat replacing beef as a negative control): 100, 84, 97, 7, 7, 0 and 0%. To detect any allergenic cross-reactivity between poultry meat-based and feather hydrolysate-derived extracts, an IgE ELISA inhibition was also done. Ten canine sera with the highest level of anti-poultry IgE in the previous experiment were incubated overnight with a previously optimized 50 μg amount of each of the extracts used above. We performed ELISA on plates coated with chicken, duck or turkey meats with or without inhibitors. The median inhibition percentages after incubation with the non-hydrolyzed chicken meal were ~22%, with the mildly-hydrolyzed poultry feathers: 14–22%, and those with the extensively-hydrolyzed poultry feathers: 5 to 10%; the last inhibition level was similar to that of the beef meat negative control.

Conclusions

Altogether, these results suggest that an extensive—but not partial—hydrolyzation of the poultry feather extract is necessary to prevent the recognition of allergenic epitopes by poultry-specific IgE.

Electronic supplementary material

The online version of this article (doi:10.1186/s12917-017-1183-4) contains supplementary material, which is available to authorized users.

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

BACKGROUND

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.

HYPOTHESIS/OBJECTIVES

To test commercial diets labelled as suitable for elimination diets for dogs, for DNA of animal origin other than that declared on the label.

METHODS

Twelve commercial dry and tinned dog food products were investigated for DNA of animal origin (chicken, turkey, beef, mutton and pork) using PCR testing.

RESULTS

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.

CONCLUSIONS AND CLINICAL IMPORTANCE

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.

Food-specific sublingual immunotherapy is well tolerated and safe in healthy dogs: a blind, randomized, placebo-controlled study

BACKGROUND

Food allergies are increasing in prevalence but no treatment strategies are currently available to cure dogs with food allergy. Over the past decade, experimental food allergen-specific sublingual immunotherapy (FA-SLIT) has emerged as a potential treatment for food allergies in human medicine. However, FA-SLIT has not been investigated in dogs. Therefore, the objective of this study was to prospectively evaluate the safety, tolerability and dispenser sterility of FA-SLIT in healthy dogs before testing it in food allergic dogs. Eight experimental healthy beagle dogs, never orally exposed to peanut, were randomized in two groups to receive SLIT with peanut or placebo for 4 months. Subjects were monitored daily for local and systemic adverse effects. Blood samples for complete blood count and serum biochemistry, and urine for urinalysis were collected and the dogs' body weight was recorded at day 0, 35 and 119 of the SLIT treatment. Sera for the determination of peanut-specific IgG and IgE were collected at day 0, 35, 49, 70, 91, 105 and 119. Intradermal tests were performed before (day 0) and after (day 119) the experiment. The content of each dispenser used to administer treatment or placebo was tested for sterility after usage. In order to assess the presence or absence of sensitization, dogs were challenged 6 months after the end of the study with 2000 μg of peanut extract daily for 7 to 14 days.

RESULTS

All dogs completed the study. The treatment did not provoke either local or systemic side-effects. Peanut-specific IgG significantly increased in treatment group. Even though a significant increase in peanut-specific IgE was also seen, intradermal tests were negative in all dogs before and after the experiment, and the challenge test did not trigger any adverse reactions in the treated dogs, which shows the protocol did not cause sensitization to peanut, but nevertheless primed the immune system as indicated by the humoral immune response. All dispenser solutions were sterile.

CONCLUSIONS

Our results demonstrate that the used peanut-SLIT protocol is well tolerated and safe in healthy dogs. Further studies should evaluate tolerability, safety and efficacy in dogs with food allergy.

Detection of undeclared animal by-products in commercial canine canned foods: Comparative analyses by ELISA and PCR-RFLP coupled with slab gel electrophoresis or capillary gel electrophoresis

BACKGROUND

The potential presence of undeclared animal by-products in pet foods is not subject to routine examination. Previously published methods for species-based identification of animal by-products have not been used routinely owing to inconsistent results. The present study evaluated the utility of several approaches for accurate identification of animal by-products in 11 commercial brands of canine canned foods.

RESULTS

Canine canned foods from several countries were analysed by ELISA, PCR-RFLP coupled with slab-gel electrophoresis (SGE) and capillary gel electrophoresis (CGE) to test for evidence of by-products derived from cattle, chicken, sheep or pig. While CGE-based analysis detected all (24) animal-derived by-products that were reported for the 11 test samples, SGE and ELISA detected only 22/24 (92%) and 14/24 (58%) of labelled by-products, respectively. In addition, undeclared animal by-products were found using all three analytical approaches with CGE detecting more positives (19) than SGE (17) or ELISA (5).

CONCLUSION

Significant disparities were evident between the labelled contents and the detected content of animal by-products. CGE-based testing for PCR products appears to provide greater sensitivity and accuracy than either SGE or ELISA-based methods. As testing of commercial products becomes more reliable and mainstream, manufacturers will need to develop more thorough and accurate labelling protocols.

Determination of mammalian deoxyribonucleic acid (DNA) in commercial vegetarian and vegan diets for dogs and cats

The determination of undeclared ingredients in pet food using different analytical methods has been reported in recent years, raising concerns regarding adequate quality control, dietary efficacy and the potential for purposeful adulteration. The objective of this study was to determine the presence or absence of mammalian DNA using multiplex polymerase chain reaction (PCR) on diets marketed as vegetarian or vegan for dogs and cats. The diets were tested in duplicate; two samples were purchased approximately 3 to 4 months apart with different lot numbers. Multiplex PCR-targeted mitochondrial DNA with two species-specific primers was used to amplify and sequence two sections of the cytochrome b gene for each of the 11 mammalian species. Half of the diets assessed (7/14) were positive for one or more undeclared mammalian DNA source (bovine, porcine, or ovine), and the result was repeatable for one or more species in six diets. While most of the detected DNA was found at both time points, in some cases, the result was positive only at one time point, suggesting the presence may have been due to unintentional cross-contact with animal-sourced ingredients. DNA from feline, cervine, canine, caprine, equine, murine (mouse and rat) and leporine was not identified in any samples. However, evidence of mammalian DNA does not confirm adulteration by the manufacturer nor elucidate its clinical significance when consumed by animals that may benefit from a vegetarian or vegan diet.

Treatment of canine atopic dermatitis: 2015 updated guidelines from the International Committee on Allergic Diseases of Animals (ICADA)

Background

In 2010, the International Task Force on Canine Atopic Dermatitis (now International Committee on Allergic Diseases of Animals, ICADA) published the first consensus guidelines for the treatment of atopic dermatitis (AD) in dogs. This is the first 5-year minor update of this document.

Results

The treatment of acute flares of AD should involve the search for, and then elimination of, the cause of the flares, bathing with mild shampoos, and controlling pruritus and skin lesions with interventions that include topical and/or oral glucocorticoids or oclacitinib. For chronic canine AD, the first steps in management are the identification and avoidance of flare factors, as well as ensuring that there is adequate skin and coat hygiene and care; this might include more frequent bathing and possibly increasing essential fatty acid intake. The medications currently most effective in reducing chronic pruritus and skin lesions are topical and oral glucocorticoids, oral ciclosporin, oral oclacitinib, and, where available, injectable recombinant interferons. Allergen-specific immunotherapy and proactive intermittent topical glucocorticoid applications are the only interventions likely to prevent or delay the recurrence of flares of AD.

Conclusions

This first 5-year minor update of the international consensus guidelines for treatment of AD in dogs further establishes that the treatment of this disease is multifaceted, and that interventions should be combined for a proven (or likely) optimal benefit. Importantly, treatment plans are likely to vary between dogs and, for the same dog, between times when the disease is at different stages.

Electronic supplementary material

The online version of this article (doi:10.1186/s12917-015-0514-6) contains supplementary material, which is available to authorized users.

Canine atopic dermatitis: detailed guidelines for diagnosis and allergen identification

BACKGROUND

Canine atopic dermatitis (AD) is a common, genetically predisposed, inflammatory and pruritic skin disease. The variation in clinical presentations, due to genetic factors, extent of the lesions, stage of the disease, secondary infections, as well as resemblance to other non-atopic related skin diseases, can complicate a diagnosis of canine AD. A sub-group of the International Committee for Allergic Diseases in Animals (ICADA) was tasked with the development of a set of practical guidelines that can be used to assist practitioners and researchers in the diagnosis of canine AD. Online citation databases and abstracts from international meetings were searched for publications related to the topic, and combined with expert opinion where necessary. The final set of guidelines was approved by the entire ICADA committee.

RESULTS

A total of 81 publications relevant for this review were identified. The guidelines generated focus on three aspects of the diagnostic approach: 1. Ruling out of other skin conditions with clinical signs resembling, or overlapping with canine AD. 2. Detailed interpretation of the historical and clinical features of patients affected by canine AD. 3. Allergy testing by intradermal versus allergen-specific IgE serum testing.

CONCLUSIONS

The diagnosis of canine AD is based on meeting clinical criteria and ruling out other possible causes with similar clinical signs. Flea combing, skin scraping and cytology should be performed, where necessary, as part of a thorough work-up. Elimination diet trials are required for patients with perennial pruritus and/or concurrent gastrointestinal signs. Once a clinical diagnosis of canine AD is made, allergy testing can be performed to identify potential causative allergens for allergen-specific immunotherapy.

Investigation into the animal species contents of popular wet pet foods

Background

The use of the generic term “meat and animal derivatives” in declared ingredient lists of pet foods in the European Union is virtually universal. In the wake of the 2013 “horse meat scandal” in the human food chain, we examined the presence and authenticity of animal sources (cow, chicken, pig and horse) of proteins in a range of popular wet pet foods in the United Kingdom.

Findings

Seventeen leading dog and cat foods were sampled for the relative presence of DNA from each of the four animal species by quantitative real-time polymerase chain reaction. No horse DNA was detected. However, there was detection at substantial levels of unspecified animal species in most products tested. In 14 out of 17 samples, bovine, porcine and chicken DNA were found in various proportions and combinations but were not explicitly identified on the product labels. Of the 7 products with prominent headline descriptions containing the term “with beef”, only 2 were found to contain more bovine DNA (>50%) than pig and chicken DNA combined.

Conclusions

There is a need for the pet food industry to show greater transparency to customers in the disclosure of the types of animal proteins (animal species and tissue types) in their products. Full disclosure of animal contents will (a) allow more informed choices to be made on purchases which are particularly important for pets with food allergies, (b) reduce the risk of product misinterpretation by shoppers, and (c) avoid potential religious concerns.