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Visual and DNA breed identification of dogs and comparison of inter observer reliability

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https://www.eduzhai.net American Journal of Sociological Research 2013, 3(2): 17-29 DOI: 10.5923/j.sociology.20130302.02 Comparison of Visual and DNA Breed Identification of Dogs and Inter-Observer Reliability Victoria L. Voith1,*, Rosalie Tre ve jo2, Se ana Dowling-Guye r3, Colette Chadik1, Amy Marde r3, Vanessa Johnson1, Kristophe r Irizarry1 1College of Veterinary M edicine, Western University of Health Sciences, Pomona, 91766, United States of America 2Oregon State University, Beaverton, 97006, United States of America 3Center for Shelter Dogs, Animal Rescue League of Boston, Boston, 02116, United States of America Abstract Until the recent advent of DNA analysis of breed composition, identification of dogs of unknown parentage was done visually, and visual identification is still the most common method of breed identification. We were interested in how often visual identification o f dogs by people, assumed to be knowledgeable about dogs, matched DNA breed identification and how often these people agreed with each other (inter-observer reliability). Over 900 participants who engaged in dog related professions and activities viewed one-minute, color video-clips of 20 dogs of unknown parentage and were asked to identify the dogs’ predominant breeds. For 14 of the dogs, fewer than 50% of the respondents visually identified breeds of dogs that matched DNA identification. Agreement among respondents was also very poor. Krippendorf’s alpha was used to exa mine the reliability of the most predominant breed (selected across all dogs identified as mixed breeds) for all respondents, yielding alpha=0.23. For only 7 of the 20 dogs was there agreement among mo re than 50% of the respondents regarding the most predominant breed of a mixed breed and in 3 o f these cases the most commonly agreed upon visual identification was not identified by DNA analysis. Keywords Inter-observer Re liability of Dog Breed Identification,Visual and DNA Identificat ion of Mixed Breed Dogs 1. Introduction The breed by which a dog is identified has important implications and ramifications. Breed identificat ion is used in public health journals, veterinary medical records, lost and found notices, licensing documents and animal shelter descriptions. How a dog is identified also influences how people interpret a dog’s behavior. World-wide, public and private regulations and restrictions have been enacted that regulate dog ownership, euthanasia, availab ility of liab ility insurance, and access to housing. These rules may specify specific breeds, mixes of these breeds, or any dog that resembles these breeds. We were interested in how often visual identification of dogs by people assumed to be knowledgeable about dogs matched DNA breed identification, and how often these people agreed with each other (inter-observer reliability). Estimates of the prevalence of specific breeds of dogs that engage in in jurious behaviors appear in nu merous published articles related to public health, canine behavior, andveterin ary med icine. Dat a con cern ing dog b reeds, * Corresponding author: vvoith@westernu.edu (Victoria L. Voith) Published online at https://www.eduzhai.net Copyright © 2013 Scientific & Academic Publishing. All Rights Reserved particularly pertain ing to hu man in juries, are frequently tabulated from newspaper accountsor retrospective reviews of hospital and animal control records[1-10]. So metimes dogs in these reports are identified by owners according to what they believe is the most predo minant breed of their dog[4],[6],[9] or fro m informat ion entered in veterinary med ical records based on the staffs’ assessments[9],[11]. Generally, published reports supply no data on who identifiedthe dogs’ breeds[12]. Adding to the confusion, data are often published in a manner that comb ines dogs identified as purebreds with purebred crosses, e.g. the German Shepherd Dogand German Shepherd cross would bedepicted as German Shepherds[4],[7]; all dogs identified as pit bull breeds and pit bull hybrids would be categorized as a pit bull[10]. Although such publications may include cautionary statements that thebreed identifications were unverified, potentially inaccurate, and that data on the numbers and breeds of dogs in the source population were unknown[3-7], breed frequencies are still included in the p u b licatio n s . With the intention of providing public safety, regional and national governments have attempted to regulate dog ownership, how a dog is maintained, and impose euthanasia policies based on the perceived breed co mposition of a dog, be it a purebred or mixed breed[12-20]. Insurance premiu ms and housing restrictions are also based on a dog’s 18 Victoria L. Voith et al.: Comparison of Visual and DNA Breed Identification of Dogs and Inter-Observer Reliability breed composition[8],[19],[20]. Until the recent advent of DNA analysis of breed co mposition[21-25] identification of dogs of unknown parentage was done visually, and visual identification is still the most common method of breed identification, even by law enforcement, animal care and control agencies, and veterinarians[19],[20],[26]. As examples, see the animal control ordinances of Prince George’s County Maryland, Denver Co lorado, and Victoria, Melbourne Australia[27-29]. Our personal observations of discrepancies among people who attempt to visually identify the breed composition of dogs prompted this study. We were interested in how often visual identificat ion by people assumed to be knowledgeable about dogs was in agreement with DNA identification, and how often people agreed with each other (inter-observer reliab ility). We felt this was important because of the potential ra mifications of misclassificat ion of dog breeds in published databases which drive public and private policies as well as people’s perceptions of the behavior of indiv idual dogs. People who engage in professions or services that involve dogs are one source of identification of dogs of unknown parentage. They are in a position to provide their opinion to owners about the possible breed or predo minant breed of their dogs. They may also directly assign a breed identity to dogs and enter their opinions on office forms and/or records. Either way, these identifications have the potential to be entered into national databases which are used for prevalence statistics on dogs’ breeds. 2. Methods The protocol for the study was approved by the Institutional Review Board and Institutional Animal Care and Use Committee of the Western University of Health Sciences, Po mona Californ ia. 2.1. Source of Partici pants The participants were recruited by contacting organizations involved in dog-related activ ities, such as veterinary med ical groups, animal control/sheltering agencies, dog clubs, and regional and national conferences related to veterinary medicine and dog-related activities. Permission was requested to administer an anonymous, voluntary, dog breed identificat ion quiz and survey (collect ively referred to as the questionnaire), followed by an educational presentation. It was asked that the participants be at least 18 years old and able to understand and write English. At the time of the presentations, the participants were also informed that participation was anonymous, voluntary, could be discontinued at any time and that their responses were part of a research project. These sessions were administered in person, by either the Principle Investigator or a trained research assistant, at 30 locations in the following states: Arizona, Californ ia, Co lorado, Louisiana, Massachusetts, Missouri, Ohio, Tennessee, Texas, Utah, and Washington. Many of these sites were at regional or national meetings with participants fro m several states. 2.2. Source of Dogs Twenty privately-owned dogs of unknown parentage were selected for the study from a pool of dogs that had been volunteered by their owners to participate in dog breed identification studies[26]. Forty of 50 volunteered dogs met the entrance criteria of being mature enough to have fully erupted canine teeth, having been obtained from a shelter, rescue, anima l control or simila r adoption agency, and being available on a specific day to be videotaped and have blood drawn. The 40 dogs were assigned to one of 4 weight ranges: ≤20 lbs. (9.07 kg), 21-40 lbs. (9.52-18.14 kg), 41-60 lbs.(18.60- 27.22 kg ), and > 60 lbs. (27.22 kg). Five dogs were randomly selected fro m each weight range and entered into the study. The study dogs included 7 castrated males, 12 spayed females and 1 intact female. They had been adopted fro m 17 d ifferent locations in North A merica but currently residing in Southern California. Figure 1 depicts each study dog against a white screen with a b lack-lined grid o f one-foot squares. The pictures are freezed frames fro m the videotapes that were shown to the participants. Detailed descriptions of each dog are provided Table 1. 2.3. DNA Analysis Two ml samp les of heparinized b lood fro m each dog were immed iately refrigerated and sent on the same day on cold packs by overnight shipment to MARS VETERINA RYTM Lincoln, Nebraska for DNA analysis. There were 130 A merican Kennel Club (AKC) reg istered purebreds in their database and the laboratory reported “an average of 84% accuracy in the first-generation crossbred dogs of known parentage”[22],[23]. Contributions of ancestral breeds less than 12.5% were not reported. The laboratory had in their database the AKC breed A merican Staffordshire Terrier but not any breeds identified as Pit Bull or A merican Pit Bull Terrier. Because of the common ancestry, historical reciprocal registrations, and similar morphology, we used visual identifications of American Staffordshire Terrier, Pit Bu ll, and A merican Pit Bu ll Terrier as matches to the DNA identification of A merican Staffordshire Terrier. For several years, the American Kennel Club (AKC) allowed dogs to be registered as Staffordshire Terriers (later changing the name to A merican Staffordshire Terrier) if the dogs were already registered as American Pit Bull Terriers in the United Kennel Club (UKC) or A merican Dog Breeders Association (ADBA) registries. Until 2010, the UKC permitted registration of AKC and ADBA dogs as American Pit Bull Terriers. AKC registered American Staffordshire Terriers are still allowed to be registered as American Pit Bull Terriers in the ADBA[30-33].We are not, however, suggesting that they are identical. For each dog, the breeds identified by DNA were classified as Major or M inor based on the relative American Journal of Sociological Research 2013, 3(2): 17-29 19 percentage of the breed represented in that dog. Breeds reported at the highest percentage of DNA in a dog were classified as Major; breeds reported at lower percentages in that dog were classified as Minor. A dog could have mo re than one Major DNA breed identification, e.g., three breeds each represented at 25%. If only one breed was detected in a dog by DNA analysis, that breed was considered the Major breed, even if it was only 12.5% o f the dog’s composition. Results of the DNA analyses of breed identification of each dog are in Tab le 1. None of the dogs were reported to be purebreds by DNA analysis. 2.4. Admi nistration of Study Questionnaire Admin istration of the questionnaire and following educational program took about 55 minutes. The participants were shown one minute, color video-clips of each of the 20 dogs which were allowed to move about in front of a white screen with a black-lined grid of one-foot squares. Full bilateral and frontal views and a close up of the head were depicted. The participants were told the age, weight, and sex of each dog as they viewed the videos. After each video-clip, the respondents were given as much time as they requested to write in their answers. The video-clips were not re-shown. The respondents were required to generate their answers. They did not have access to resource materials and were asked not to solicit breed identifications fro meach other. In our experience, most dogs are often visually identified quickly as either a single breed or a single breed mix, generally without consulting resources. The video-clips were always shown the same order (Dog 1-20) which was the order that the owners, at their convenience, had brought their dogs to be videotaped. 2.5. The Survey and Quiz Questions Participants were asked to indicate: their current and past professional activities; if they now or ever have been asked what breed a dog appears to be; if their opinions have ever been used to assign possible breed identities for the purposeof records (e.g. shelters, medical, licensing, other businesses); and personal descriptive questions such as their age and sex, how many dogs they have, and if they have ever competed in any dog related activities, such as showing, agility, hunting, etc. For each dog, the respondents were asked: -“Do you think this dog is probably a purebred?” □ YES □ NO -“If YE S, (you think this IS probably a purebred) What breed do you think it is?” -“If NO, (you do NOT think t his a purebred) What do you think is the most predominant breed?” -“What do you thi nk is the second most predominant breed. (If you are unable to determine a second breed, write “Mix” here. Otherwise, name a breed.)” In this article, identificat ion as “not a purebred” is used synonymously with “mixed-breed”. The answer to the most predominant breed of a M ixed Breed is referred to as the Primary Visual Identification (PVI) and an answer to the second most predominant breed is referred to as the Secondary Visual Identification (SVI). Figure 1. Pictures of the 20 study dogs against a backdrop of 1 foot square grid of 1 foot squares 20 Victoria L. Voith et al.: Comparison of Visual and DNA Breed Identification of Dogs and Inter-Observer Reliability Table 1. Descriptions of the 20 Study Dogs and Percent of Major and Minor Breeds Identified by DNAAnalysis Dog ID 1 Sex Approximate Age Weight – lbs. (kg) Major Breeds Identified by DNA Minor Breeds Identified by DNA FS 3 Years 51 (23.1) American Staffordshire Terrier**; Saint Bernard** Chinese Shar-Pei* 2 FS 9 Years 31 (14.1) American Eskimo Dog**; Golden Retriever**; Nova Scotia Duck-Tolling Retriever**; Rottweiler** 3 MC 5 Years 60 (14.1) English Springer Spaniel**; German Wirehaired Pointer** Australian Cattle Dog*; Bischon 4 MC 2.5 Years 26 (11.8) Lhasa Apso** Frise*; Italian Greyhound*; Pekingese*; Shih T zu* 5 FS 12 Years 51 (23.1) Australian Shepherd Dog*; Chow Chow*; Dalmatian*; German Shepherd*; Siberian Husky* 6 FS 5 Years 54 (24.5) Chow Chow*; Dachshund*; Nova Scotia Duck -Tolling Retriever* 7 MC 10 Months 15 (6.8) American Water Spaniel*; Black Russian T errier*; Pomeranian*; Shih Tzu*; Tibetan Terrier* 8 FS 2 Years 41 (18.6) Chow Chow**; French Bull Dog** Clumber Spaniel* Dalmatian* ; Gordon Setter*; Great Dane* 9 FS 7 Years 66 (30) Dalmat ian ** Boxer*; Chow Chow* ; Newfoundland* 10 MC 5.5 Years 10 (4.5) Australian Shepherd Dog**; Pekingese** 11 MC 3 Years 62 (28.1) American Staffordshire Terrier**; German Shepherd Dog** Bull Terrier* Chow Chow* 12 FS 1.5 Years 52 (23.6) Australian Shepherd Dog*; Boxer*; Dachshund*; Dalmatian*; Glen of ImaalT errier* 13 MC 3.5 Years 79 (35.8) Alaskan Malamute* 14 FS 3.5 Years 74 (33.6) German Shepherd Dog**; Standard Schnauzer** English Setter* 15 FS 7 Years 70 (31.8) Chow Chow*; Golden Retriever*; Gordon Setter*; Saint Bernard* 16 F 5.5 Months 20 (9.1) Australian Shepherd Dog*; Boxer*; Golden Retriever* 17 FS 2 Years 18 (8.2) Cavalier King Charles Spaniel*; Chihuahua*; Shih Tzu* 18 FS 10 Months 13 (5.9) Miniature Pinscher***; Dachshund* 19 FS 12 Years 36 (16.3) Border Collie** Bassett Hound*; Cocker Spaniel* 20 MC 6 Years 21 (9.5) Shih Tzu** Cocker Spaniel*; Miniature Schnauzer*;Pekingese* Percent of breed composition detected by DNA: *12.5%; **25%; *** 50%. FS, female spay; MC, male castrate; FI, female intact. Dogs of unknown parentage are generally designated by only one breed, e.g., Chow mix, German Shepherd mix[26]. We believe that when a dog is so identified, the assumption is that the named breed is the most predominant breed in the dog’s ancestry. Therefore, we wanted to know how often our respondents’ visual identification of the most predominant breed matched breeds identified at the highest percentage by DNA analysis. Secondarily, we were interested in whether or not a breed visually identified as the most predominant matched any breed identified by DNA, regardless of the percentage of DNA co mposition. And third ly, we examined whether any visual identification, either the first or second breed identified, matched any percentage of DNA breed identified. 3. Results Nine hundred eighty six people co mpleted all or part o f a questionnaire. The questionnaires of 63 respondents were excluded fro m analysis for the following reasons: did not answer or answered “No” to the question “Are you now, or have you ever been asked what breed a dog appears to be.”; did not provide any info rmation regarding their professions; or indicated they were less than 18 years old. Respondents were asked to indicate on the questionnaire if a specific dog was theirs or if they knew a dog’s DNA co mposition; data pertaining to these dogs were not included in the study, although data provided by the respondent pertaining to other dogs were included. All responses pertaining to a specific dog were tabulated, unless the answer was illegible. 3.1. Profile of Res pondents Most respondents indicated involvement in mo re than one dog-related profession/service, either sequentially or simu ltaneously.The majority of respondents were or had been in animal control/sheltering and/or veterinary medical fields, see Figure 2. People in animal control and veterinary med ical fields were significantly more likely to have their opinions of a dog’s breed used for record keeping purposes than not have their opinions so used (p0.05). A t-test indicated no significant difference regard ing age. See appendix for co mparisons of participants’ personal d emo g rap h ics . 3.2. Comparison of Visual Identification and DNA Breed Identi ficati on The DNA analysis indicated none of the dogs were purebreds and most respondents identified the study dogs as mixed breeds. See Table 3. Ho wever, 7 of the 20 dogs were visually identified as probably purebreds by ten percent or more (range 10% - 25.4%) of the respondents. An average of 9.2 % (1701/ 18408) of the responses were “yes” to the question “Do you think this dog is probably a purebred?”. A positive match between visual and DNA identification occurred if (1) the respondent indicated that the dog was not a purebred and (2) also specified a breed identified by DNA.The following were NOT considered matched res p o ns es : if the dog was visually identified as a purebred (even if the breed identified was one identified as part of the dog’s composition by DNA analysis) OR if the dog was visually identified as not a purebred but identified as breed that was not reported by DNA analysis. For each dog, the percent of respondents whose visual identification matched the DNA identificat ion was calculated by div iding the nu mber of matched responses for a dog (numerator) by the sum of matched and unmatched responses (denominator). For each dog, we looked at how often visual and DNA identification matched at the three progressively less stringent levels: •Level 1: Respondent indicated that the dog was NOT a Purebred AND the most predominant breed (Primary Visual Identificat ion/ PVI) matched at least one of the Major DNA Identificat ions for that dog. •Level 2: Respondent indicated that the dog was NOT a Purebred AND the PVI matched any DNA Identification (Major or Minor) of that dog. •Level 3: Respondent indicated that the dog was NOT a Purebred AND EITHER PVI or SVI (second most predominant breed) visual identification matched any DNA Identificat ion of that dog. There we re few significant statistical differences between those who had their opinions used for record keeping purposes (Group A) and those who did not have their opinionsso used (Group B) regarding the frequency with which v isual and DNA identification matching occurred at any of the 3 levels of matching stringency. See appendix for comparisons of the two groups at the 3 levels of matching stringency. We concluded the few differences between groups A and B to be of no practical significance and combined the groups for subsequent analysis. Table 3. Number and Percent of Respondents That Answered “Yes,” They Thought the Dog was a Purebred Dog ID 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Overall Yes/Tot al 18/918 63/917 92/917 17/919 120/920 36/920 79/919 75/922 234/921 134/919 116/922 81/922 71/921 36/922 59/921 32/922 48/921 172/922 25/919 193/919 1703/18403 P ercent 2.0% 6.9% 10.0% 1.8% 13.0%` 3.9% 8.6% 8.1% 25.4% 14.6% 12.6% 8.8% 7.7% 3.9% 6.4% 3.5% 5.2% 18.7% 2.7% 21.0% 9.2% DNA analysis indicated that none of the dogs were purebred The combined data showed that as the stringency levels for matching deceased, the percentage of matches increased. However the agreement between visual and DNA identification was low at all three levels, see Table 4. There were no matches of visual and DNA identifications at Level 1 for five dogs, no matches for four dogs at Level 2, and at Level 3, the most liberal criteria, no matches for one dog. For 8 dogs, fewer than 5% of the respondents’ visual identifications matched any DNA identification at Level 3; for only 6 dogs did more than 50% of the respondents’ visual identifications match any DNA identification. 3.3. Inter-Observer Reliability of Visual Identification of Most Predominant Breed of Dogs Identified as Mi xed Breeds Agreement among the respondents was also very poor, see Table 5 and see appendix. There was agreement among more than 50% of the respondents regarding the most predominant breed of a mixed breed for only 7 dogs and for 3 of these dogs the visual identification did not match any (either major or minor) DNA breed identificat ion Krippendorff’s alpha was used to examine the reliability of the most commonly visually identified predominant breed (selected across all dogs identified as mixed breeds) for all respondents, yielding alpha=0.23 which is generally considered to represent low levels of inter-observer reliability[34],[35].The data was treated dichotomously, the respondents either provided the same answer (b reed) or not. American Journal of Sociological Research 2013, 3(2): 17-29 23 Table 4. Percent and Number of Respondents Whose Visual Identification Matched DNA Breed Identification for Each Dog at 3 Levels of Matching St rin gen cy Dog ID 1* 2 3 4 5 6 7 8 9 10 11* 12 13 14 15 16 17 18 19 20 LEVEL 1:PVI Matched a Major DNA Breed Ident ificat ion P ercent Yes / Total 33.20% 290/873 43.00% 369/859 7.20% 62/863 0.10% 1/852 72.90% 653/896 0.00% 0/856 1.90% 17/872 0.00% 0/862 70.40% 639/908 0.00% 0/884 53.70% 471/877 0.10% 1/831 0.00% 0/859 29.50% 260/880 0.20% 2/890 27.10% 218/805 56.60% 496/877 0.00% 0/869 10.80% 89/821 33.30% 283/849 LEVEL 2:PVI Matched Any DNA Breed Ident ificat ion P ercent Yes / Total 35.70% 312/873 43.00% 369/859 7.20% 62/863 9.40% 80/852 72.90% 653/896 0.00% 0/856 1.90% 17/872 0.60% 5/862 70.50% 640/908 0.00% 0/884 53.70% 471/877 0.10% 1/831 0.00% 0/859 29.50% 260/880 0.20% 2/890 27.10% 218/805 56.60% 496/877 0.00% 0/869 11.00% 90/821 38.20% 324/849 LEVEL 3:PVI or SVI Matched Any DNA Breed Identification P ercent 62.80% 53.10% 11.90% 12.40% 81.90% 0.10% 4.60% 1.90% 73.00% 0.10% 64.50% 0.40% 0.00% 47.50% 0.70% 31.80% 75.30% 0.10% 14.60% 44.90% Yes / Total 550/876 457/860 103/863 106/852 734/896 1/856 40/872 16/862 664/909 1/884 566/877 3/831 0/859 418/880 6/890 256/805 661/878 1/869 120/821 381/849 PVI, Primary Visual Identification; SVI, Secondary Visual Identi fication; Any DNA Breed Identi fication, Major or Minor Breed relative repres entation in a dog. *American Staffordshire Terrier (AST), Pit Bull and Pit Bull Terrier visual identifications were considered matches to DNA analysis breed identification of AST. Percentages in bold indicate over 50% of the visual identifications matched DNA identi fications. Table 5. Breed of Dog Most Often Visually Identified as Primary (PVI) in Dogs Also Visually Identified as a Mixed Breed Dog ID Breed Identified by Greatest Percentage of Respondents Percent Identifying That Breed Number of Respondents 1 Labrador Retriever 39.9% 855 2 Golden Retriever 39.3% 796 3 Border Collie 45.7% 771 4 P ug 37.0% 835 5 GERMAN SHEPHERD DOG 59.1% 777 6 German Shorthaired Pointer 33.0% 820 7 CORGI 56.7% 793 8 PIT BULL/AS T* (39.5%/12.1%) 51.6% 787 9 DALMATIAN 94.8% 674 10 Yorkshire T errier 16.6% 751 11 GERMAN SHEPHERD DOG 61.2% 762 12 Labrador Retriever 16.4% 750 13 German Shorthaired Pointer 14.4% 790 14 German Shepherd Dog 30.8% 844 15 LABRADOR RETRIEVER 86.9% 831 16 Australian Shepherd Dog 23.9% 774 17 CHIHUAHUA 55.5% 831 18 Cairn T errier 23.5% 697 19 Collie 20 Shih Tzu 14.6% 796 43.2% 657 *AST, American Staffordshire Terrier. PVI=Most Predominant Visual Identification. Breeds in UPPERCASE and bold indicate over 50% of the respondents were in agreement 24 Victoria L. Voith et al.: Comparison of Visual and DNA Breed Identification of Dogs and Inter-Observer Reliability 4. Discussion This study reveals a wide disparity between DNA and visual identification of the predo minant breeds comprising a dog. It also indicates a low level o f agreement among people regarding breed co mposition. Those of us in the animal care services have always remarked on the differences of opinions regarding what breed a dog is but few are aware of how little agreement there is or how often one’s own opinion could be wrong. The wide range of responses by the participants are compatible with research and theories pertaining to judgments of probability based on partial information[36-42]. Identificat ion of the breed composition of a dog requires recognition and recall, both of wh ich are in fluenced by a mu ltitude of variables, such as perception, knowledge base, memo ry, recent or salient experiences with the subject matter, and cognitive abilities involving categorizat ion, sorting, matching and reco mbination of features. Identificat ion is affected by what features (stimu li) a person notices and how much weight the person attributes to those features. For example, some people may attend to the hair coat and colo r pattern of a dog, while others focus on size, shape of head, or whether or not the tail is curled. The ease with which people notice a feature enhances recall and increases the weight that is placed on that feature. For example, so much significance is placed on any black pigmentation of a dog’s tongue that, regardless of the morphology of the dog, it is usually identified as a Chow Chow o r Chow mix. The frequency with wh ich people are exposed to the names of specific breeds of dogs and their perception of the population of specific b reeds will also influence prediction. Interestingly, the literature indicates that well educated professionals are as susceptible to judgmental b iases as are the lay public[36],[37],[43],[44]. The low percentage of agreement between visual and DNA identificat ion may be partially exp lained by perception biases. However, DNA identification of the p roportion of purebred breeds in mixed breed dogs is not perfect e ither, nor do the laboratories that provide such analyses claim to be infallible. The average accuracy of identification of the breeds in an individual dog can be expected to decrease as the heterogeneity of its ancestors increases. Canine HeritageTM states that their accuracy of identification of known reg istered purebred dogs is 99%[45]. W isdom PanelTM currently reports a 90% average accuracy of identification ofF1 crosses of known reg istered purebred d o gs [46] . After co mpleting the quiz, the DNA results were revealed to the participants. Ho wever, it was not until we showed them pictures of the F1 and F2 cros ses of registered purebred dogs[47] did the participants begin to realize that mixed breed dogs may not look like theirpurebred parents or grandparents. The mixed breeds bore little, if any resemblance, to their purebred parents or grandparents. Crosses of purebred dogs (particularly beyond the firstgeneration) can result in unique combinations and a collage of features.In fact, the pictures of Scott and Fuller’s dogs looked more like breeds other than their immediate ancestors. Many current breeds were derived by crossing existing breeds or by selecting for morphological variations within a breed until a “new” breed was established[25],[30]. It actually shouldn’t be surprising that visual identification of mixed breeds does not always agree with DNA based breed identification. A recent genetic study in dogs determined that very few regions of the canine genome encode morphologica l tra its associated with breed-defining physical traits[48]. Dogs have on the order of 20,000 to 25,000 genes and fewer than 1% o f the dog’s genes control the external morphological features associated with specific breeds of dogs, such as ear shape and size, whether the ears are floppy, length of the legs, length of the coat, coat color and shape of the head and length of mu zzle. A dog could genetically be 50%a German Shepherd Dog and lack the genomic regions responsible for the German ShepherdDog size, coat color, mu zzle length and ear properties. Even after Scott and Fuller’s pictures were shown, there was reluctance to consider that the DNA results might be correct. This is co mpatible with observations that people often adhere to their beliefs even when data is present that contradicts their beliefs and the confidence with which people adhere to these beliefs may actually increase when presented with contradictory data[36],[44],[49]. Misidentificat ion of a dog’s breed composition is not a trivial matter. Ho w a dog is identified can affect many people and dogs. Dog ownership is common world wide[50-53].In the United States approximately 40% of households have at least one dog,there is an increasing trend to obtain dogs from animal shelters/humane societies, and ownership of mixed breeds is increasing compared to purebreds[50],[51]. 4.1. Li mitati ons of the Study It is possible that the breeds of these 20 dogs in this study are unusually difficult to identify visually. Similar studies should be conducted with other samples of dogs and by other res earch ers . 5. Conclusions The disparities between visual and DNA identification of the breed composition of dogs and the low agreement among people who identify dogs raise questions concerning the accuracy of databases which supply demographic data on dog breeds, as well as the justification and ability to implement laws and private restrictions pertaining to dogs based on breed composition. ACKNOWLEDGEMENTS We thank Elizabeth Arps, Dan Estep, John R. Greenwood, Janis Joslin, and Katherine Mitsouras for their help. The DNA breed analysis was provided by MARS VETERINA RYTM Lincoln, NE 68501-0839. Th is study was American Journal of Sociological Research 2013, 3(2): 17-29 25 partially supported by the National Canine Research Council, LLC, 433 Pugsley Hill Rd, A menia, NY 12501. APPENDIX Table 6. Comparisons of Respondents’ Personal Demographics by Whether or Not Their Opinions Were Used to Assign Dog Breed Respondent Gender Respondent Age P art icip at io n in Do g-Relat ed Act iv it ies Own/Reside with Dogs Female Male N Mean Median St an dard Dev iat ion N Yes No N Yes No N All Re spondents 75.7% 24.3% 875 37.6 35.0 12.5 826 30.3% 69.7% 909 82.9% 17.1% 890 GROUP A n =7 02 Opinions Use d to Assign Breed Identi ties in Re cords 74.2% 25.8% 677 37.3 35.0 12.0 642 GROUP B n =2 21 Opinion s NO T Used to Assign Breed Identi ties in Re cords 80.8% 19.2% 198 38.9 38.0 14.0 184 29.8% 31.7% 70.2% 701 83.8% 16.2% 687 68.3% 208 79.8% 20.2% 203 Stat Test Re sult (comparing Group A to B) χ2=3.687 N/A t =-1 .42 7 χ2=0.279 N/A χ2=1.806 N/A N/A p 0.055 0.155 0.597 N/A 0.179 N/A N/A χ2=Chi-Square. t=Student t-test. N= Number answering this question. Not all participants answered each of the questions Table 7. Comparison and Percent of Level 1 Matches for Groups A and B Dog ID 1* 2 3 4 5 6 7 8 9 10 11* 12 13 14 15 16 17 18 19 20 GROUP A Opinions Use d for Re cords % (n / N) 33% (224 / 679) 40.8% (273 / 669) 7.4% (50 / 674) 0% (0 / 664) 72.8% (500 / 687) 0% (0 / 669) 2.4% (16 / 671) 0% (0 / 672) 69.8% (484 / 693) 0% (0 / 679) 51.6% (350 / 678) 0.2% (1 / 653) 0% (0 / 671) 28.2% (192 / 680) 0.3% (2 / 684) 27.5% (176 / 640) 54.6% (371 / 680) 0% (0 / 671) 11.9% (77 / 647) 32.4% (213 / 657) GROUP B Opinions NO T Use d for Re cords % (n / N) 33.2% (66 / 199) 48.7% (96 / 197) 6.2% (12 / 193) 0.5% (1 / 202) 73.2% (153 / 209) 0% (0 / 192) 0.5% (1 / 205) 0% (0 / 194) 72.1% (155 / 215) 0% (0 / 210) 59.6% (121 / 203) 0% (0 / 192) 0% (0 / 196) 33.2% (68 / 205) 0% (0 / 210) 23.1% (42 / 182) 61.6% (125 / 203) 0% (0 / 203) 6.3% (12 / 190) 35.9% (70 / 195) Chi-S qua re p 0.002 0.963 3.907** 0.048 0.326 0.568 Fisher's Exact T est=0.233 0.015 0.904 NA Fisher's Exact T est=0.142 NA 0.399 0.528 NA 4.002** 0.045 Fisher's Exact T est=1.000 NA 1.849 0.174 Fisher's Exact T est=1.000 1.423 0.233 3.127 0.077 NA 4.822** 0.028 0.82 0.365 *American Staffordshire Terrier (AST), Pit Bull and Pit Bull Terrier visual identifications were considered matches to DNA analysis breed identification of AST n/N number of matches for that dog/Number of respondents that answered the question for that dog.**significant at p < 0.05 level 26 Victoria L. Voith et al.: Comparison of Visual and DNA Breed Identification of Dogs and Inter-Observer Reliability Table 8. Comparison and Percent of Level 2 Matches for Groups A and B Dog ID 1* 2 3 4 5 6 7 8 9 10 11* 12 13 14 15 16 17 18 19 20 GROUP A Opinions Use d forRecords % (n / N) 35.9% (244 / 679) 40.8% (273 / 669) 7.4% (50 / 674) 10.1% (67 / 664) 72.8% (500 / 687) 0% (0 / 669) 2.4% (16 / 671) 0.6% (4 / 672) 70% (485 / 693) 0% (0 / 679) 51.6% (350 / 678) 0.2% (1 / 653) 0% (0 / 671) 28.2% (192 / 680) 0.3% (2 / 684) 27.5% (176 / 640) 54.6% (371 / 680) 0% (0 / 671) 12.1% (78 / 647) 37.7% (248 / 657) GROUP B Opinions NO T Use d for Re cords % (n / N) 34.2% (68 / 199) 48.7% (96 / 197) 6.2% (12 / 193) 6.4% (13 / 202) 73.2% (153 / 209) 0% (0 / 192) 0.5% (1 / 205) 0.5% (1 / 194) 72.1% (155 / 215) 0% (0 / 210) 59.6% (121 / 203) 0% (0 / 192) 0% (0 / 196) 33.2% (68 / 205) 0% (0 / 210) 23.1% (42 / 182) 61.6% (125 / 203) 0% (0 / 203) 6.3% (12 / 190) 39% (76 / 195) Chi -Square p 0.209 0.647 3.907** 0.048 0.326 0.568 2.467 0.116 0.015 0.904 NA Fisher's Exact T est=0.142 Fisher's Exact T est=1.000 0.35 0.554 NA 4.002** 0.045 0.294 0.587 NA 1.849 0.174 Fisher's Exact T est=1.000 1.423 0.233 3.127 0.077 NA 5.042 0.025 0.096 0.757 *American Staffordshire Terrier (AST), Pit Bull and Pit Bull Terrier visual identifications were considered matches to DNA analysis breed identification of AST n/N number of matches for that dog/Number of respondents that answered the question for that dog. **significant at p < 0.05 level Table 9. Comparison and Percent of Level 3 Matches for Groups A and B Dog ID 1* 2 3 4 5 6 7 8 9 10 11* 12 13 14 15 16 17 18 19 20 GROUP A Opinions Use d for Re cords % (n / N) 62.5% (425 / 680) 52.2% (350 / 670) 12.5% (84 / 674) 13.4% (89 / 664) 82.8% (569 / 687) 0.1% (1 / 669) 5.4% (36 / 671) 2.1% (14 / 672) 72.6% (503 / 693) 0.1% (1 / 679) 63% (427 / 678) 0.5% (3 / 653) 0% (0 / 671) 45.4% (309 / 680) 0.6% (4 / 684) 31.9% (204 / 640) 73.7% (502 / 681) 0.1% (1 / 671) 15.9% (103 / 647) 44.1% (290 / 657) GROUP B Opinions NO T Use d for Re cords % (n / N) 62.2% (125 / 201) 54.3% (107 / 197) 9.8% (19 / 193) 8.4% (17 / 202) 78.9% (165 / 209) 0% (0 / 192) 2% (4 / 205) 1% (2 / 194) 74.5% (161 / 216) 0% (0 / 210) 68.5% (139 / 203) 0% (0 / 192) 0% (0 / 196) 53.2% (109 / 205) 1% (2 / 210) 28.6% (52 / 182) 78.3% (159 / 203) 0% (0 / 203) 8.9% (17 / 190) 46.7% (91 / 195) Chi -Square p 0.006 0.263 0.983 3.587 1.626 Fisher's Exact T est=1.000 Fisher's Exact T est=0.054 Fisher's Exact T est=0.545 0.319 Fisher's Exact T est=1.000 2.052 Fisher's Exact T est=1.000 NA 3.776 Fisher's Exact T est=0.630 0.721 1.762 Fisher's Exact T est=0.630 5.813 0.388 *American Staffordshire Terrier (AST), Pit Bull and Pit Bull Terrier visual identifications were considered matches to DNA analysis breed identification of AST .n/N number of matches for that dog/Number of respondents that answered the question for that dog. **significant at p < 0.05 level

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