伴侣动物食物不良反应批判性评价话题(5):商品化宠物食品...

王帆

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

伴侣动物食物不良反应批判性评价话题(5):商品化宠物食品中成分和说明不一致

作者Thierry Olivry and Ralf S. Mueller

翻译：王帆

Abstract

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.

Keywords: Canine, Cat, Contamination, Diet, Dog, Feline, Food allergy, Labeling, Pet foods

摘要

背景:用于诊断犬和猫的食物不良反应(食物过敏)的日粮限制试验经常结合商品化宠物食品一起分析，同时依靠其说明来选择那些以前没吃过的食物成分。有人担心，工业化生产的宠物食品可能含有未列出的食物来源，可能会使食物试验无效。此外，不明成分可能导致对这些过敏的患者出现临床过敏反应。

结果:我们在2017年7月7日和2018年1月12日检索了两篇相关文章的数据库，并从世界领先的兽医皮肤病学大会上筛选出合适的材料的摘要。在选定的论文中发现了更多的引用文献。我们总共从17篇文章和1篇摘要中提取了数据。这些研究在宠物食品测试的数量(中位数:15;范围:1至210)和专门评估的成分(中位数:4;范围:1到11)上都有所不同。研究最常使用PCR方法检测DNA或用ELISA方法来鉴定蛋白质来源是来自一种或多种植物或动物;两项研究使用质谱分析法加强对蛋白质数量的检测。各种方法发现，0 - 83%(中位数:45%)的测试日粮中含有说明上没有的成分;这一比例在含有新奇/限制性成分的用于日粮排除试验的宠物食品中变化为33%到83%。同样，有0 - 38%(中位数:1%)的测试食品说明的成分不全。最后，六项研究评估了几种含有水解成分的宠物食品:只有一种日粮发现了含有未列出或成分不全的错误说明。

结论:宠物食品说明错误现象很常见，即使是那些含有新奇或限制性成分，被推荐用于日粮排除试验的宠物食品也不例外。意外添加的成分比说明不全的成分更容易被检测到。没有足够的信息来确定存在污染成分是否会导致对其过敏的患者出现临床过敏反应，因为对此类成分过敏的犬或猫并没有使用说明错误的食品进行激发试验。对含有水解成分的宠物食品的检测发现，只有一例可能有错误说明。

关键词：犬科、猫、污染、日粮、犬、猫科、食物过敏、说明、宠物食品

Background

背景

To diagnose an adverse food reaction (i.e. food allergy) in a canine or feline patient, a lengthy period of dietary restriction is followed by sequential food challenges to identify the culprit food allergen(s). At this time, the restriction phase is most commonly performed by feeding commercially-available pet foods while relying on the ingredients written on the label to select an elimination diet not containing previously eaten food items. Likewise, after the diagnosis of adverse food reaction is made, the patient is maintained on a diet expected not to contain the offending allergens. At this stage again, veterinarians and pet owners are relying on the proper labeling of commercial pet foods to select a diet not containing the offending allergens. There are concerns that commercial foods may be contaminated with unexpected ingredients, either at the stage of ingredient selection or during their manufacturing. The rate of pet food with incorrect labeling, either with ingredients not on, or missing from, the label is not widely known.

要诊断犬或猫的食物不良反应(即食物过敏)，首先要进行一段长时间的日粮限制试验，然后紧接着进行食物激发，以确定致病的食物过敏原。此时，限制阶段最常见的做法是饲喂已有的商品化宠物食品，同时依靠成分说明选择一款不含以前吃过的成分的日粮进行日粮排除试验。同样地，在确诊食物不良反应后，患犬应继续保持饲喂不含过敏原的日粮。在这一阶段，兽医和宠物主人再次依赖商品化宠物食品的明确的说明来选择不含过敏原的日粮。有人担心，商品化食品可能会在成分选择阶段或在生产过程中被不明的成分污染。成分不在列或者成分不全的错误说明的宠物食品的比例尚不明确。

Clinical scenario

临床病例

Your patient is a 3-year-old male castrated German shepherd dog that you had diagnosed four years ago with food-induced atopic dermatitis. A previous dietary trial had established that this dog’s pruritus and skin lesions had completely resolved following an elimination diet with a hydrolysate-containing pet food. Signs had relapsed in the day following an oral challenge with chicken, an ingredient present in its first adult diet. During the past two years, this dog had been eating a fish-and-rice dog food, and its atopic dermatitis had remained in complete clinical remission. Due to a problem with the supply of his usual pet food, the owner recently changed it to another fish-and-rice over-thecounter diet from a different manufacturer. Within one day of starting the new diet, this dog began having a severely pruritic erythematous patchy and papular eruption on the abdomen and axillae. The owner does not understand why her dog is having a flare of atopic dermatitis, as the ingredients listed on the diet’s label are similar to those eaten previously. You suspect that this new diet might include some chicken and you wonder how commonly pet food ingredient mislabeling occurs.

你的病例是一只3岁的德国牧羊犬，已去势公犬，四年前被你诊断为食物诱发性特应性皮炎。以前的日粮排查试验已经证实，经过饲喂水解宠物食物进行限制性日粮管理，这只犬的瘙痒症状和皮肤病变能得到完全改善。在口服鸡肉激发后，在第二天症状复发了，此成分是它第一次吃的成犬粮中的成分。在过去的两年里，这只犬一直吃鱼肉米饭犬粮，它的特应性皮炎症状一直达到临床改善状态。由于他常用的宠物食品供应出现了问题，主人最近换了另一厂家的鱼肉米饭日粮。在吃新日粮的一天之内，这只犬开始在腹部和腋窝出现严重的瘙痒性红斑片和丘疹。主人不明白为什么她的犬特应性皮炎突然发作，因为日粮说明上的成分和以前吃的很相似。你怀疑这种新的日粮可能包括一些鸡肉，你想知道宠物食品出现成分说明错误有多普遍。

Structured question

问题框架

Do commercial pet foods commonly contain ingredients not listed on their labels?

商品化宠物食品是否普遍发生含有说明上没有列出的成分?

Search strategy

检索方法

We queried the Web of Science Core Collection and CAB Abstract databases on two occasions, July 7, 2017 and January 12, 2018 with the following search string: (dog or dogs or canine or cat or cats or feline or pet or pets) and (food* or diet*) and commercial and (contamination or ingredient* or antigen* or allergen*). Altogether, the search was limited to the years 2000– 2017, and there was no limit of publication language. The bibliography of each selected article was then screened for additional papers that could be of interest. We also looked for relevant information in the published abstracts from North American, European and world congresses of veterinary dermatology. Finally, additional database searches were done with the first author’s names of identified abstracts of interest to determine if full-length articles later reported the same material.

我们分别于2017年7月7日和2018年1月12日查询两次网络科学核心期刊和CAB文摘数据库网站，搜索内容如下:(犬或犬（复数）或犬科或猫或猫（复数）或猫科或宠物或宠物（复数）)和(食品*或日粮*)和商品化和(污染或成分*或抗原*或过敏原*)。所有的搜索时间范围是2000年到2017年，并且出版语言不限。然后筛选每一篇选定文章中可能相关的参考文献。我们还在北美、欧洲和世界兽医皮肤病学会议上发表的摘要中寻找相关信息。最后，对确认的相关摘要的第一作者的名字进行额外的数据库搜索，以确定后期报道的全文中是否材料相同。

Identified evidence

确凿证据

Our widest search identified 145 and 151 citations in the Web of Science and CAB abstracts, respectively. Among these, we found only three relevant articles, two of which were included in both databases. The search of the published congress abstracts yielded four additional summaries, and a further query of databases with the abstracts’ lead author’s name resulted in three articles missed by our original search. Finally, 12 additional articles were identified from screening the bibliography of previously-selected papers Altogether, we reviewed the information included in 18 articles and one abstract. One paper was later discarded, as it only dealt with treats and supplements and not pet foods. In all, we retained 18 reports of pertinent information.

我们通过大范围搜索发现，科学核心期刊网和CAB文摘网分别有145和151条引用。在这些文献中，我们只找到了3篇相关文献，其中2篇两个数据库都有收录。对已发表相关摘要的搜索额外发现了4个摘要，而对以该摘要第一作者的名字在数据库中进一步查询，使得我们去除了最初搜索的3篇文章。最后，从之前的论文的参考文献中，我们又筛选出了12篇文章。一共审查了18篇文章和1篇摘要中的信息。后来去除了一篇论文，因为它只调查了零食和补充剂，而非宠物食品。最终，我们保留了18份相关信息的报告。

Evaluation of evidence

证据评估

The studies had been conducted with diets purchased in seven countries: the USA (five studies) , Spain (five–all from the same research group), Italy (two), Taiwan (two) , France (two), and the United Kingdom and Austria with one each (Additional file 1: Table S1). The tested diets had been purchased in the general distribution or from veterinarians, and they consisted of either dry and wet foods or treats for everyday use. In six instances, the tested pet foods had been proposed as an aid for the diagnosis or management of adverse food reactions, as they were labelled to contain “limited” or “novel” or hydrolyzed ingredients (Additional file 1: Table S1). Regrettably, only six articles specifically reported the brand of the tested diets .

研究数据包括七个国家的可购买日粮:美国（5项研究）、西班牙(5项-所有来自同一研究小组)、意大利(2项)、台湾(2项)、法国(2项)、英国和奥地利各1项(额外的文件1:表S1)。测试的日粮来自普遍供应或从兽医处购买，包括每天饲喂的干粮和湿粮或零食。在6个案例中，被测试的宠物食品被推荐用于诊断或管理食物不良反应，因为它们的说明含有限制性或新奇或水解成分(附加文件1:表S1)。遗憾的是，只有6篇文章明确报道了测试日粮的品牌。

The studies varied both in the number of pet foods tested (median: 16; range: 1 to 210) and that of ingredients specifically evaluated (median: 4; range: 1 to 11). All but three studies employed PCR techniques to amplify the DNA from a single (e.g. beef, chicken, wheat…) or a group of species (e.g. avian, fish, poultry, leporids…). Two reports from the same group mentioned ELISAs being used to test for the presence of one or more protein source. Finally, it is only in the two last studies that one of the methods used (i.e. mass spectrometry) might, at least in theory, permit the detection of a potentially infinite number of contaminating proteins .

这些研究在宠物食品测试数量(中位数:16;范围:1至210)和特定评估成分(中位数:4;范围:1到11)上各不相同。除了三项研究外，所有研究都使用了PCR技术来扩增单一物种(如牛肉、鸡肉、小麦)或一组物种(如鸟类、鱼类、家禽类、兔类)的DNA。来自同一组的两份报告提到ELISA方法被用来检测存在一种或多种蛋白质来源。最后，只有在最后的两项研究中，使用的其中一种方法(即质谱分析法)，至少在理论上，可能允许检测潜在的无限数量的污染蛋白。

We analyzed the study results both for data suggesting the presence of unlabeled potentially allergenic ingredients, but also for evidence demonstrating the absence of components written on the label (Additional file 1: Table S1). Altogether, the percentage of tested pet foods with mislabeled ingredients varied from 0 to 83% (median: 45%; Additional file 1: Table S1; Fig. 1). Even in studies testing pet foods with “novel/limited” ingredients proposed for elimination (i.e. restrictive) diets, the percentage of mislabeling varied from 33 to 83% of evaluated foods . Interestingly, except for one instance, the pet foods with hydrolyzed proteins were not found to contain protein sources from an unexpected species. In the study with potential mislabeling of a hydrolysate-containing diet, the authors considered the possibility of cross-contamination, but they also discussed the hypothesis that a previously unknown potato protein homologous to the detected rice protein might have been missing from the database used to match the sequences identified by mass spectrometry .

我们分析了研究结果，既有数据表明存在未标记的潜在致敏成分，也有证据表明未在说明上注明成分(附加文件1:表S1)。总的来说，含有错误成分的测试宠物食品的百分比从0到83%不等(中位数:45%;附加文件1:表S1;图1)。即使在含有新奇/限制性成分的推荐用于日粮排除试验的(即限制性日粮)宠物食品的检测研究中，错误说明的比例也从33到83%不等。有趣的是，除了一个例以外，含有水解成分的宠物食品并没有发现其他来源的的蛋白质。在这项研究中,水解日粮说明错误的可能,作者认为有交叉污染的可能性,但他们也讨论了假设一个未知的马铃薯蛋白质同源检测大米蛋白可能是缺少数据库用于匹配序列被质谱。

Overall, the identity of the mislabeled ingredient(s) varied depending upon the method of testing, which had been set up to detect one or more protein or DNA source, and details are provided in Additional file 1: Table S1.

总的来说，明确错误成分会因检测方法不同而不同，检测方法是用来检测一个或多个蛋白质或DNA源的，详细信息见附加文件1:表S1。

In all but one article, the methods used (ELISA or PCR) permitted an estimation of the rate of ingredients missing from the label. Such missing ingredient(s) were found in 8/16 studies (50%; Additional file 1: Table S1) and the rate of mislabeled diets varied between 0 and 38% (median: 1%; Additional file 1: Table S1), a percentage negligible compared to that of ingredients not present on the label. Missing ingredients were not detected in the tested pet foods that contain hydrolysates.

除了一篇文章外，所有文章使用的方法(ELISA或PCR)都允许对说明中缺失成分的比率进行估计。在8/16项研究中(50%;附加文件1:表S1)和误标率在0和38%之间变化(中位数:1%;附加文件1:表S1)，与说明上没有的成分相比，这个百分比可以忽略不计。在测试的含有水解成分的宠物食品中没有检测到成分不全。

Limitations

局限性

This review of the existing evidence on pet food mislabeling highlighted several limitations that should be taken into consideration before translating these results to clinical practice. Firstly, it is very likely that the rate of pet food mislabeling, either due to unlabeled or missing food ingredients, is higher than that reported herein. This underestimation stems from the methods used that, except for the last studies that used mass spectrometry, only looked for the presence or absence of a small number of specific ingredients. Secondly, these reports usually would not be able to determine if the mislabeling was due to the cross-contamination of the food supply or manufacturing lines or to a deliberate misleading intent (i.e. a deliberate fraud). Finally—and most importantly—the presence of an ingredient not included in a pet food’s label does not imply that a patient allergic to this particular food source would have a clinical reaction to this contaminant. Indeed, an individual’s clinical reactivity depends upon a combination of factors including the type of allergen(s) recognized by the patient’s immune system, the amount of mislabeled allergen(s) present in the pet food and the degree of hypersensitivity of the patient itself.

本文综述了现有的关于宠物食品说明错误的证据，并强调了在将这些结果转化为临床实践之前应该考虑的几个限制性。首先，很有可能是由于宠物食品说明未标注或食品成分不全造成的错贴率比本文报道的要高。这种低估源于使用的方法，除了最后使用质谱分析法研究外，只寻找少量特定成分存在或不存在。其次，这些报告通常无法确定错误说明是由于食品供应或生产线的交叉污染，还是蓄意误导(即蓄意欺诈)。最后，也是最重要的是，宠物食品说明中没有包含的成分并不意味着对这种特定食物原过敏的病例会对这种污染物产生临床过敏反应。事实上，一个病例的临床过敏反应取决于多种因素的组合，包括病例免疫系统识别的过敏原类型、宠物食品中错误标记的过敏原的数量以及病例自身的过敏程度。

Conclusion and implication for practitioners

结论与启示

Our review of the literature suggests that the mislabeling of pet foods is 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 ingredient will lead to a clinical reaction in a patient allergic to it, as challenges with the mislabeled foods were not performed in allergic dogs or cats allergic to such ingredients. The testing of hydrolysatecontaining pet foods found only one instance with possible mislabeling.

我们对文献的回顾表明，宠物食品的错误说明是相当普遍的，即使是那些含有新奇或限制性成分，推荐用于日粮排除试验的日粮。未知成分比说明上缺失的成分更容易被检测到。目前还没有足够的信息来确定污染成分的存在是否会导致对其过敏的患者出现临床过敏反应，因为对此类成分过敏的犬或猫没有进行错误说明日粮的激发测试。对水解成分宠物食品的测试发现，只有一种可能存在错误说明。

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