DOI: 10.5061/dryad.ffbg79cz9
title: Comparison of behavioural tendencies between 'dangerous dogs' and other domestic dog breeds – evolutionary context and practical implications

description: Aggressive behaviour by dogs is a considerable social problem, but the
 ability to predict which individuals may have increased aggressive
 tendencies is very limited, restricting the development of efficient
 preventive measures. There is a common perception that certain breeds are
 more likely to exhibit aggressive behaviour, which has contributed to the
 introduction of breed-specific legislation. The rationale for such
 legislation explicitly assumes high heritability of this trait while also
 implying relatively little variation within breeds; these assumptions are
 largely untested. We compared behavioural tendencies between 8 breeds that
 are subject to legislation in at least one country and 17 breeds that are
 not subject to legislation using two validated psychometric tools: the Dog
 Impulsivity Assessment Scale (DIAS), which scores elements of impulsivity,
 including a tendency for aggressive behaviour, and Positive and Negative
 Activation Scale (PANAS), which scores sensitivity to positive and
 negative stimuli (which may trigger aggressive responses). We found that
 the two groups of breeds do not differ significantly in the specific DIAS
 factor relating to aggressive behaviour, “Aggression Threshold and
 Response to Novelty”, or any other DIAS and PANAS factors. We found large
 variation in all behavioural tendencies measured by both psychometric
 scales within both groups and within each breed studied. Taken together,
 our findings indicate that breed alone is not a reliable predictor of
 individual behavioural tendencies, including those related to aggression,
 and therefore breed-specific legislation is unlikely to be an effective
 instrument for reducing risk.
description: Data were gathered via owner report using an online survey
 combining demographic information with the Dog Impulsivity Assessment
 Scale and the Positive and Negative Activation Scale. The website link was
 advertised online (via Facebook and relevant dog/breed specific groups,
 Twitter, pet fora, via the UK Kennel Club including their Bio-acquisition
 Research Collaboration page, and the Dog Science Group website). UK
 breeders of breeds of interest were emailed using the ChampDogs website
 and encouraged to participate. Participants were informed we were
 conducting research into breed differences in personality traits, but were
 not specifically informed about the primary research focus on
 breed-specific legislation. To select legislated dog
 breeds for inclusion, a list of countries with breed-specific legislation
 was compiled (PETolog, 2017; RSPCA, 2016). Legislated breeds were then
 selected based on the criterion that the breed is banned or restricted in
 at least one country that has breed-specific legislation. Using this
 criterion, we identified 12 dog breeds and two breed “types” (Dogo
 Argentino “type” and Pit Bull “type”) subject to legislation. We focused
 on responses from dog owners living in the UK and the Republic of Ireland.
 A very limited number of dog breeds/types is banned in the UK, and
 therefore we could obtain data on breeds legally owned in the UK but
 banned in other countries. We did not attempt to collect data from dog
 breeds/types banned in the UK, but our online questionnaire was open to
 the public without restriction, and therefore we obtained some data on
 banned dog breeds from the British Isles as well. The UK legislation bans
 Pit Bull “type” dogs, and we obtained too few entries to create a separate
 group for this breed type. However, we pooled data from three individuals
 described as “Pit Bull type” (of unspecified breed) and one Dogo Argentino
 individual together with other legislated breeds in a comparison of
 legislated versus non-legislated types. The Staffordshire bull terrier is
 not banned in the UK, and was considered separately from “Pit Bull
 types”. In order to define non-legislated breeds, the
 following criteria were used: (a) the breed was not classified as a
 legislated breed, (b) the breed did not belong to the same genetic cluster
 as any of the legislated breeds (since it was assumed closely-related
 breeds may show behavioural similarities resulting from common ancestry),
 and (c) data on the breed were available in our questionnaire database.
 With the exception of the breeds banned in the UK, all breeds had to be
 registered in the Kennel Club (UK). All dogs listed as crosses were
 excluded. Pedigree status could not be checked and so breed information is
 based solely on owner report.  In addition to comparing
 the legislated versus non-legislated breed groups, we investigated
 differences between individual breeds. From the set of breeds used in that
 comparison, we selected breeds that had a sample size ≥ 20 individuals,
 with the exception of two legislated breeds - English Bull Terrier and
 Rhodesian Ridgeback. These two breeds were included in the breed-level
 analysis despite smaller sample sizes due to their relevance to the
 primary research question. This resulted in 8 legislated breeds and 17
 non-legislated breeds used in the breed-level analysis.
 DIAS and PANAS questionnaires The DIAS
 consists of 18 items rated on a 5-point Likert scale: “strongly agree”,
 “agree”, “partly agree, partly disagree”, “disagree”, “strongly disagree”,
 with “not applicable” as the sixth option; 9 items are reverse scored.
 Values are summed and the total divided by five times the number of scored
 items to give an Overall Questionnaire Score (OQS) value between 0.2 and
 1. The DIAS is composed of three factors: “Behavioural Regulation”,
 “Aggression Threshold and Response to Novelty” and “Responsiveness”
 (Wright et al. 2011). The scores for these factors were calculated from
 items that load on these factors according to Fadel et al. (2016). The
 PANAS is comprised of 21 items, and is scored in a similar way to the DIAS
 (Sheppard & Mills, 2002). This questionnaire is composed of two
 main factors: “Positive Activation” and “Negative Activation”.
 Duplicates, blank entries, entries with four or more missing
 responses and those for dogs less than one-year-old or owned by the
 current owner for less than a year were removed from the dataset. We also
 excluded responses from dog owners not based in the UK or Ireland, to
 reduce bias resulting from cultural or linguistic differences. We compared
 the DIAS and PANAS scores between legislated and non-legislated groups (as
 defined above) and breed level differences for breeds with at least 20
 individuals, with the exceptions noted in the previous section.
 Link to R code provided in README file. 
description: .txt files