Self-reports of Dutch dog owners on received professional advice, their opinions on castration and behavioural reasons for castrating male dogs.

Male dogs are often castrated based on the thought that it facilitates well-behavedness. However, the causal evidence for this from prospective studies lacks and the existing associative studies present mixed results depending on the studied behaviours. We aimed to gain insight into possible factors driving an owner's decision to castrate their male dog, through a quantitative survey based on a convenience sample. We determined the advice owners received from three types of dog professionals (veterinarian practitioners, behavioural trainers, behavioural therapists) and the owners' assessments of castration's behavioural effects. Data on 491 Dutch owners of castrated and intact male dogs were analysed with Chi-square tests. Results indicate that owners of both castrated and intact dogs received castration advice most often from veterinarian practitioners, with pro-castration at higher frequencies for owners of castrated dogs (Chi-square, P<0.001). Overall, most owners disagreed with or were neutral about statements on castration positively affecting male dog behaviour at a population level. Nevertheless, 58% (N = 145) of the owners of castrated dogs (N = 249) reported that correcting unwanted behaviour was a reason to castrate their own male dog. Unwanted behaviour involved aggression in 50% (N = 70) of the owner-dog dyads. Castrated dog's aggression changes were reported on most as 'no change'. The second most common answer indicated an aggression decrease in dogs castrated to correct unwanted behaviour and an increase in dogs castrated for other reasons (Chi-square, P<0.001). The increase in aggression in a subset of castrated dogs is concerning, as aggression can pose risks to the dog's welfare. We acknowledge the limitations of our study which identifies associations rather than provides causal evidence. Still, we recommend professionals' awareness of possible negative behavioural changes following castration, like increased aggression. Future research on behavioural consequences of castrating dogs needs to build a more solid knowledge base for balanced advice regarding castration.

1. Introduction

Desexing dogs regards the surgical removal of the testes in males, more commonly known as castration, or the ovaria in females. Desexing is a common practice in Western societies. Percentages of 54% of 431 British dogs [1] and of 78% of 413 Australian dogs [2] illustrate how the desexing of dogs is common practice, also in regions where dog reproduction is under control. Dog owners may deem desexing ‘the right thing to do’, as 74% of 1,016 dog owners considered desexing a practice that their relatives would agree with, 69% reported desexing to be important and 62% expected favourable outcomes of desexing [3]. Thus, the common belief is that desexing makes a dog more well-behaved, but convincing causal scientific evidence for the precise behavioural effects of desexing dogs is presently lacking. This compromises the quality of the advice to dog owners by dog professionals such as veterinarian practitioners, behavioural trainers (also known as dog trainers), and behavioural therapists. These dog professionals ordinarily provide the science-based information that misses in a dog owner’s cordial social surroundings [4]. Therefore, we aimed to establish why dog owners decide to castrate their male dog or not and which professional advice, to which avail, is reportedly received by them. Our findings should contribute to a future understanding of how professional advice may support carefully weighed decisions by dog owners on the castration of their dog.

Carefully weighed decisions on castrating dogs are necessary as the scientific information on the effects of desexing dogs, males in particular, is complex and to date incomplete. Strong causal evidence on castration affecting a broad range of behaviour is lacking [5, 6]. Castration of the male dog has been related to reduced inter-male aggression, marking and roaming [7, 8], indicating possible benefits of the procedure. Also, dog bite risk at the population level was higher for intact than desexed dogs [5]. However, effect sizes ranged across the six reviewed studies. Moreover, confounders were considered important to better understand desexing effects on dog behaviour and these confounders regarded for example breed and desexing age, but also environment, such as dog care practices [5]. The complexity increases by findings of desexing associating with unwanted behaviours like fear and types of aggression other than inter-male aggression [9, 10, 11, 12, 13, 14]. The mechanism behind the found associations is that sex hormones are known to have a muting effect on the stress system [15]. For instance, men with higher levels of the sex hormone testosterone have lower levels of pain and fear [16], and for fear this was demonstrated also in male mice [17]. Extrapolation of these findings to male dogs would mean that castration-induced drops in testosterone levels raises fear levels. Since fear is a common motivational factor for aggression in dogs [18, 19, 20], an increase in fear following castration could increase a dog’s aggression. Indeed, in a cross-sectional study castrated male dogs (N = 16) acted more fearfully and aggressively than intact males (N = 18) when interacting with each other during behavioural tests [12]. Indefinite study outcomes that also include female dogs even further complicate the already complex relation between desexing and behaviour. There was no difference in aggression levels between English Cocker Spaniels that were desexed and intact, at least after excluding dogs that were desexed for reasons of correcting unwanted behaviours [21]. Also, no evidence for aggression changes in desexed dogs was found in a large survey-based study on 13,237 to 13,795 dogs [22]. This again after excluding the dogs that were desexed for reasons of correcting unwanted behaviour and when considering multiple aggression affecting factors [22]. With this complexity in findings on desexing and behaviour and the lack of causal evidence [5, 6], how dog owners are advised becomes of interest. This as there is reason to assume that desexing facilitates aggression in a subset of dogs. Aggression is a common burdensome unwanted behaviour. It was diagnosed in 16–72% (depending on the aggression type) of 1,644 dogs included in a retrospective case series evaluation of medical records [18] and reported by as many as 36% of 174 South Korean dog owners [9]. Also, aggression was the main reason for behavioural consultation in a study population of 140 dogs, of which 129 were desexed [23], and aggression associated with high perceived costs of dog ownership and with reduced ownership satisfaction [24]. Strongly reduced ownership satisfaction due to a dog’s unwanted behaviour may ultimately lead to dog relinquishment [25, 26, 27] or euthanasia [28]. The potential dire consequences of unwanted behaviour in dogs make it important that the decision to desex an individual dog is carefully weighed [6]. In this, the advisory role lies logically with professionals such as veterinarian practitioners, behavioural trainers, and behavioural therapists. Today, little is known about which professionals are consulted on this topic by dog owners, what advice these owners receive and how their decision to desex their dog relates to their particular opinions on desexing. These gaps in knowledge underlie the present research and we specifically address the castration of male dogs. We focus on male dogs because in our sample of dog owner reports the desexing for reasons of correcting unwanted behaviour involved males (58%, N = 145 of 249) much more often than females (11%, N = 28 of 258). Desexing may be common in female dogs, like that 83% of Australian female dogs were desexed versus 74% of males [2], but the decision to desex to correct unwanted behaviour seems to involve especially males.

In regions where dog reproduction is under control, dog owners should weigh the benefits and risks of desexing on the basis of balanced and correct information. Dog professionals such as veterinarian practitioners, behavioural trainers, and behavioural therapists may provide the advice that owners need, and we aimed to establish possible factors driving dog owners’ decisions to castrate male dogs, including the factors of owner received professional advice, their opinions on castration and behavioural reasons for castrating male dogs. More insight into how owners opinion and decide on castrating their male dog can benefit professional advice, thus allowing owners to make carefully weighed decisions. These decisions ultimately benefit the dog’s welfare and the owner-dog relationship.

2. Methods

2.1. Web-based survey and participant recruitment

A convenience sample of dog owners filled out an internet survey on the desexing of both male dogs and female dogs. Survey items were developed by us, as we were unaware of previous instruments being developed for measuring on the factors of our interest. We pretested the survey with native speakers for understanding and readability. We then analysed the owners’ reports in particular for how they were advised by dog professionals on the castration of male dogs, how they opinioned on castration affecting male dog behaviour at a population level and how owners of castrated dogs evaluated the behavioural effects of castration on their own dog specifically. Finally, we studied how satisfied owners of castrated and intact dogs were with having their dog. We targeted dog owners via websites, social media channels and newsletters directed at dog owners. Once posted through these channels, the survey could be shared by dog owners and content managers. We are unaware of studies characterizing the population of Dutch dog owners and could not compare our study sample to information on this population. By gathering and describing demographic characteristics of our study sample, we aimed to provide some insight on the participants to our convenience sample. The survey introduction explained how we considered intact as ‘no modification’ and desexed as ‘surgical removal of testes or ovaria’. We excluded reports on chemically desexed dogs and focussed on irreversible surgical desexing. Also, we excluded reports on dogs that were desexed before they were obtained by their current owner, since such owners had not been involved in the decision to desex and could not assess the behavioural changes following desexing.

The survey consisted of a first part and a second part that varied in length, depending on the dog being intact or desexed (see S1 Appendix for survey items). The first part assessed characteristics of the owner and dog, being the owner’s gender, education level and age and the dog’s sex, current age, age at acquisition by the current owner, breed, pedigree, desexing status, and age at the moment of desexing. Furthermore, owners indicated the percentage of time that they take care of the dog for which they filled in the survey, and we excluded owners who indicated that they take care of the dog less than 50% of the time. This part of the survey also held questions on the owners’ opinion on the behavioural effects of desexing and owners scored their general dog ownership satisfaction as ‘not at all satisfied’, ‘not very satisfied’, ‘moderately satisfied’, ‘satisfied’ and ‘very satisfied’. Dog ownership satisfaction scores were skewed towards (very) satisfied and the original five-point scale was expressed binary, with 1 being very satisfied and 0 being less than very satisfied. Owners expressed their opinion on how desexing affects male dog behaviour at population level, so not the behaviour of their own dog specifically, by indicating their (dis)agreement with statements on the favourable effects of desexing. Statements were on the behaviours of aggression, calmness, dog-directed sociality, dominance, human-directed sociality, mounting, roaming, trainability and urine marking, and were for instance ‘desexing diminishes aggression in male dogs’ and ‘desexing makes male dogs calmer’. Participants could answer by selecting ‘strongly disagree’, ‘slightly disagree’, ‘neutral’, ‘slightly agree’ or ‘strongly agree’.

In the second part of the survey, both the owners of intact dogs and desexed dogs reported whether or not they had received advice from the different dog professionals (i.e. veterinary practitioners, behavioural trainers, and behavioural therapists) concerning the desexing of their dog. They reported on received advice as ‘not in favour of desexing’, ‘neutral’ and ‘in favour of desexing’, which hereafter we refer to as ‘con-castration’, ‘neutral’ and ‘pro-castration’. Owners of desexed dogs scored reasons for having their dog desexed on a five-point Likert scale from ‘not relevant as a reason for desexing’ to ‘the main reason for desexing’. The reason ‘to correct unwanted behaviour’ was analysed in more detail and expressed as a binary number with 1 meaning the correction of unwanted behaviour had played a role in the decision to desex, varying from a small role to main reason, and 0 meaning it had not played any role. Owners who had their dog desexed to correct unwanted behaviour were divided binary with the number 1 indicating that aggression was a behavioural problem to correct, and 0 meaning it had not played any role. These binary scores were derived from a four-point Likert scale that ranged from ‘not problematic’ to ‘the main problem to be corrected by desexing’. The owners who had their dog desexed to correct unwanted behaviour indicated their satisfaction with the behavioural effects of desexing on a scale from ‘completely dissatisfied’, ‘slightly dissatisfied’, ‘neutral’, ‘largely satisfied’ to ‘completely satisfied’. Lastly, all owners of desexed dogs, regardless of their reason for desexing, reported how desexing had changed the prevalence of aggression. The original five-point scale of ‘strongly decreased’, ‘slightly decreased’, ‘no change’, ‘slightly increased’ and ‘strongly increased’ was converted to the three-point scale of ‘decreased’, ‘unchanged’ and ‘increased’ for further analyses.

2.2. Data processing and statistical analyses

From our full sample we excluded the participants who did not indicate their dog’s sex (male or female) and/or status (desexed or intact) and/or applicability of desexing as correction of behaviour in their dog and/or taking care of the dog at least 50% of the time. From the remaining sample of 1,006 owner reports we excluded those that involved dogs that were chemically desexed (N = 46), desexed before acquisition by the current owner (N = 95), or female (desexed N = 258, intact N = 116). Correcting unwanted behaviour had played a role in the decision to desex in only 11% (N = 28) of desexed females, but in the majority of desexed males (58%, N = 145). Thus, for this study we used the data on 491 male dogs only (castrated N = 249, intact N = 242; see Fig 1 for subsample details). The group of owners of castrated male dogs subdivided into a group of ‘owners who had their dog castrated to correct unwanted behaviour’ (N = 145) and a group of ‘owners who had their dog castrated for other reasons only’ (N = 104). The online survey allowed that the occasional question was left unanswered and the precise sample sizes used for analyses are given in the results section.

Fig 1

Subsamples within the sample of 491 owners of male dogs.

Dogs were either castrated (N = 249) or intact (N = 242). For castrated dogs, the owners indicated whether or not correcting unwanted behaviour had played a role in the decision to castrate, thus we divided the castrated dogs into ‘castrated to correct behaviour’ (N = 145) and ‘castrated for other reasons’ (N = 104).

Based on the lowest subsample size of 104 (performing Chi-square tests of df = 2), the statistical power was 0.79 for detecting at least medium effect sizes of 0.30, while maintaining an α-level of 0.05. This power was calculated using the Chi-square power calculator of the https://www.masc.org.au/. We did not set a predetermined sample size but arbitrarily aimed to detect at least medium effect sizes (√(χ2/n) > 0.30). With a statistical power of at least 0.8 [29, 30]. We tested for pairwise differences between the frequency and the nature of advice that was received from the three types of professionals, and we tested how the frequency and the nature of this advice differed between reports on castrated and intact dogs. Opinions on the effects of castration on the behaviour of male dogs at a population level were compared, also between owners of intact and castrated males. Owner perceived changes in dog aggression following castration were compared between owners who had their dog castrated to correct unwanted behaviour and owners who had their dog castrated for other reasons. Finally, general satisfaction with dog ownership was compared between owners of intact dogs, owners of dogs that were castrated to correct unwanted behaviour and owners of dogs that were castrated for other reasons. All these comparisons were made with Pearson’s Chi-square tests, maintaining a level of significance of P<0.05 and P-values are reported throughout. Chi-square values and residuals and the degrees of freedom for each Chi-square test are presented in S2 Appendix.

2.3. Ethical statement

The online survey’s introduction explained the purpose of the research and the study did not involve treatments or interventions in the life of participants or their dogs. The survey was not repeated, meaning it did not interfere significantly with normal daily life, and did not include questions that were psychologically burdening. This exempts the study from review by our ethics committee, according to the guidelines of Wageningen University Medical Ethics Review Committee (Medisch Ethische Toetsingscommissie van Wageningen University, METC-WU). Informed consent was not obtained as participants chose to participate freely via internet and the purpose of the research was stated at the start of the online survey.

3. Results

3.1. Participants and their male dogs

The participants (N = 491) were selected from the larger sample of 1,006 records as detailed in the Methods section. Typically, participants were women (89%, N = 433; men: 11%, N = 53) and over 34 years of age (<35 years: 30%, N = 146; 35–44 years: 17%, N = 84; 45–54 years: 33%, N = 160; >54 years: 21%, N = 101). The majority had completed higher professional education (52%, N = 255; vocational education above high school level: 33%, N = 162; below this level: 15%, N = 73). The majority of the male dogs were obtained by the owner before they were 10 weeks old (67%, N = 329). The remainder was obtained between 10 weeks and 1-year-old (24%, N = 116; >1-year-old: 9%, N = 44). Dogs were of various breeds and about half of them were certified pedigree dogs (54%, N = 262; 46% look-a-like or mixed breed, N = 227). The majority of dogs was aged between 1 and 8 years old (<1 year: 6%, N = 27; 1–2 years: 15%, N = 74; 2–4 years: 26%, N = 127; 4–6 years: 20%, N = 99; 6–8 years: 14%, N = 69; >8 years: 19%, N = 94). Reproductive status was near evenly distributed in our sample, with 51% (N = 249) being castrated (intact, N = 242). Of all castrated dogs, 27% (N = 68) was castrated before they were 1 year old, 40% (N = 99) was between 1 and 2 years old and 32% (N = 81) was over 2 years old at the time of castration.

3.2. Professional advice on castrating male dogs

Owners (N = 491) had received professional advice on the castration of their own dog most often from veterinarian practitioners (72%, N = 347), followed by behavioural trainers (48%, N = 224) and behavioural therapists (38%, N = 174). All three pairwise differences were significant (Chi-square tests, all P-values <0.001; for details see Table A in S2 Appendix). Of all owners who received advice (N = 380), 37% (N = 142) received advice from only one type of professional, 29% (N = 111) received advice from two types and 33% (N = 127) received advice from all three types of professionals.

We assessed how professional advice that was received by each individual owner related to the owner’s decision to castrate their own dog, by comparing the frequency of received professional advice between owners of castrated dogs (N = 249) and owners of intact dogs (N = 242) and this for each type of professional (veterinarian practitioner, behavioural trainer and behavioural therapist). Owners of castrated dogs more often than owners of intact dogs received advice from veterinarian practitioners, as opposed to not having been advised by them (81% versus 63%; P<0.001; Table 1 and for details see Table B in S2 Appendix). This difference between owners of castrated and intact dogs was not found in advice that was received from behavioural trainers (P = 0.644) or behavioural therapists (P = 0.709).

Table 1

Frequencies of advice on castrating male dogs as received from three types of dog professionals by owners of intact and castrated male dogs.

	Owners of intact dogs			Owners of castrated dogs
	Not advised	Advised	Total	Not advised	Advised	Total	P-value
Veterinarian	38% (N = 90)	63% (N = 150)	240	19% (N = 47)	81% (N = 197)	244	<0.001
Trainer	53% (N = 122)	47% (N = 110)	232	50% (N = 116)	50% (N = 114)	230	0.644
Therapist	63% (N = 147)	37% (N = 86)	233	61% (N = 140)	39% (N = 88)	228	0.709

Advice from dog professionals (veterinarian practitioners, behavioural trainers, and behavioural therapists) on the castration of male dogs was reported by dog owners (N = 491). We compare percentages of advised versus not advised between owners of intact (N = 242) and castrated (N = 249) male dogs in three Chi-square tests, one for each type of professional, and thus present P-values per professional. Subsample counts are between brackets and further details are presented in Table B in S2 Appendix.

In addition to the advice frequency, we assessed the nature of the advice that dog owners received, in terms of it being con-castration, neutral or pro-castration. Veterinarian practitioners had advised in favour of castration most often (44%, N = 171; Chi-square P = 0.005 for veterinarian practitioners versus behavioural trainers; P<0.001 for veterinarian practitioners versus behavioural therapists; for details see Table C in S2 Appendix), followed by behavioural trainers (40%, N = 89) and behavioural therapists (32%, N = 55; P = 0.028 for behavioural trainers versus behavioural therapists).

We then assessed how the nature of professional advice that was received by each individual owner related to the owner’s decision to castrate their own dog, by comparing the nature of received professional advice between owners of castrated dogs (N = 249) and owners of intact dogs (N = 242). We found that owners of castrated dogs more often than owners of intact dogs received pro-castration advice from all three types of professionals (Chi-square tests, all P-values <0.001; Table 2 and for details see Table D in S2 Appendix). The percentage of owners of castrated dogs who had received pro-castration advice from veterinarians was more than two-fold higher than the percentage of owners of intact dogs who had received this advice, and more than three-fold higher for advice from behavioural trainers and behavioural therapists.

Table 2

Nature of advice on castrating male dogs as received from three types of dog professionals by owners of intact and castrated male dogs.

	Owners of intact dogs				Owners of castrated dogs
	Pro	Neutral	Con	Total	Pro	Neutral	Con	Total	P-value
Veterinarian	29% (N = 44)	36% (N = 54)	35% (N = 52)	150	64% (N = 127)	32% (N = 63)	4% (N = 7)	197	<0.001
Trainer	18% (N = 20)	35% (N = 39)	46% (N = 51)	110	61% (N = 69)	29% (N = 33)	11% (N = 12)	114	<0.001
Therapist	15% (N = 13)	23% (N = 20)	62% (N = 53)	86	48% (N = 42)	32% (N = 28)	20% (N = 18)	88	<0.001

Advice from dog professionals (veterinarian practitioners, behavioural trainers, and behavioural therapists) on the castration of male dogs was reported by dog owners (N = 491). We compare percentages on the nature of advice being in favour of castration (pro), neutral, or against it (con) between owners of intact (N = 242) and castrated (N = 249) male dogs in three Chi-square tests, one for each type of professional, and thus present P-values per professional. Subsample counts are between brackets and further details are presented in Table D in S2 Appendix.

3.3. Owners’ opinions on the effects of castration on male dog behaviour at a population level

The owners of male dogs (N = 491) reported on how they believe castration affects the behaviour of male dogs at a population level, so not specifically the behaviour of their own dog, by rating their (dis)agreement with presumed favourable effects on nine behaviours. We combined their ratings on a five-point scale into the categories of disagreement, neutral and agreement. Owners more often disagreed with the presumed favourable effects of castration (45% of owners across the nine behaviours) than that they agreed (9%), which was more pronounced in the group of owners who owned an intact dog (51% disagreed, 8% agreed) than in the group of owners who owned a castrated dog (38% disagreed, 12% agreed). This difference was significant for trainability (P = 0.001; Table 3 and for details see Table E in S2 Appendix), mounting (P = 0.002), aggression (P = 0.005), human-directed sociality (P = 0.013) and dog-directed sociality (P = 0.018), and there was a trend for calmness (P = 0.052).

Table 3

Dog owner opinions on the effects of castration on male dog behaviour at a population level.

	Owners of intact dogs				Owners of castrated dogs
	Disagree	Neutral	Agree	Total	Disagree	Neutral	Agree	Total	P-value
Trainability	55% (N = 111)	42% (N = 85)	2% (N = 5)	201	40% (N = 61)	50% (N = 77)	10% (N = 15)	153	0.001
Mounting	48% (N = 94)	45% (N = 90)	8% (N = 15)	199	29% (N = 43)	59% (N = 89)	12% (N = 18)	150	0.002
Aggression	57% (N = 112)	40% (N = 80)	3% (N = 6)	198	44% (N = 67)	45% (N = 68)	11% (N = 16)	151	0.005
Socialityhuman	61% (N = 121)	38% (N = 75)	2% (N = 4)	200	45% (N = 69)	50% (N = 76)	5% (N = 7)	152	0.013
Socialitydog	57% (N = 114)	38% (N = 76)	5% (N = 9)	199	44% (N = 67)	46% (N = 71)	10% (N = 15)	153	0.018
Calm	47% (N = 94)	42% (N = 84)	11% (N = 23)	201	36% (N = 56)	46% (N = 72)	18% (N = 29)	157	0.052
Marking	47% (N = 94)	43% (N = 85)	10% (N = 20)	199	37% (N = 56)	49% (N = 74)	14% (N = 22)	152	0.118
Roaming	33% (N = 65)	48% (N = 96)	20% (N = 39)	200	24% (N = 36)	55% (N = 84)	22% (N = 33)	153	0.180
Dominance	53% (N = 105)	40% (N = 80)	7% (N = 14)	199	45% (N = 68)	45% (N = 68)	11% (N = 16)	152	0.250

Dog owners reported their opinion on the behavioural effects of castration in male dogs at a population level, so not specifically for their own dog. Their opinions, categorized as disagree (with favourable effects), neutral and agree, were on nine different behaviours and percentages are given separately for owners of intact dogs (N = 242) and castrated dogs (N = 249). Chi-square P-values are presented per behaviour and further details are presented in Table E in S2 Appendix.

3.4. Changes in aggression following castration of the own male dog

Owners of castrated male dogs also reported on changes in their own dog’s behaviour following castration and we were interested in changes in aggression. Generally, more than half of the owners (58%, 145 out of 249) indicated that correction of unwanted behaviour had played a role in their decision to have their dog castrated, varying from it being a side issue to the main reason. For half of these owners (70 out of 140; five missing values) the unwanted behaviour of aggression was of concern, varying from it being somewhat problematic to the main problem behaviour to correct. All owners of castrated male dogs, regardless of the reason for castration, then reported how they evaluated the changes in aggression levels in their dogs after castration, which we categorized as decreased (strongly or slightly on the original five-point scale), unchanged or increased (slightly or strongly). This question held a large number of missing values (29%, N = 72 out of 249). A decrease in aggression after castration was reported by 32% (N = 56 out of 177) of the participants who answered this question; unchanged by 51% (N = 90 out of 177) and an increase was reported by 18% (N = 31 out of 177). In more detail, we compared the owners who had their dog castrated for reasons of correcting behaviour and those who had their dog castrated for other reasons. In this comparison, owners who had their dog castrated for reasons of correcting behaviour reported to a higher degree that aggression decreased (42%, N = 48 out of 114) than owners who had their dog castrated for other reasons (13%, N = 8 out of 63; P<0.001; for details see Table F in S2 Appendix) and reported to a lower degree no changes (43%, N = 49 out of 114 versus 65%, N = 41 out of 63).

3.5. Owner satisfaction

We tested the owners’ satisfaction with castration for reasons of correcting their dog’s behaviour and we tested general ownership satisfaction for all owners. The owners who had their dog castrated for reasons of correcting its behaviour were mostly satisfied with how castration had affected the behaviour(s) of concern. Forty-seven percent (N = 65 out of 137) was completely satisfied and 25% (N = 34) was largely satisfied. Others were neutral about the effects (1%, N = 1), slightly dissatisfied (7%, N = 9) or completely dissatisfied (20%, N = 28).

General dog ownership satisfaction was expressed as a binary score of very satisfied or less than this and we compared owners of intact dogs (N = 242) with owners of dogs that were castrated to correct behaviour (N = 145) or castrated for other reasons (N = 104). Of the owners whose dogs were castrated to correct behaviour, 53% reported being very satisfied with having their dog (N = 76 out of 144). This was significantly less than owners of intact dogs (69%, N = 167 out of 241; P = 0.001) and owners of dogs that were castrated for other reasons (69%, N = 72 out of 104; P = 0.009) reported being very satisfied (Chi square tests; for details see Table G in S2 Appendix).

4. Discussion

Desexing dogs is a common practice [1, 2] that according to popular belief is ‘good for the dog’s behaviour’ [3], apparently especially when it concerns male dogs. We wanted to better understand how dog owners’ decisions to desex their dogs are influenced by professional advice and the common beliefs about the behavioural consequences. This is especially important as presently prospective causal data in this area are missing [5, 6], but individually based advice is recommended in areas where population management does not apply [6, 31]. Consequently, advising professionals such as veterinarian practitioners, behavioural trainers and behavioural therapists could benefit from information on how dog owners decide to castrate their male dog or not.

Our sample of mainly female owners of various dog breeds had a near equal spread between pedigree and non-pedigree dogs and more importantly, a near even spread on reproductive status. Owners in this particular sample reported that they received professional advice on castration most often from veterinarian practitioners (72%, behavioural trainers: 48%, behavioural therapists: 38%). Owners did not indicate the reasoning behind their professionals’ advice, and this could be based on non-behavioural reasons. Regardless of the reason, advice received from veterinarian practitioners was more often pro-castration (49%) than con-castration (17%) in which they opposed behavioural therapists (pro-castration: 32%, con-castration: 41%). Furthermore, receiving advice from veterinarian practitioners was reported more often by the owners of castrated dogs than by the owners of intact dogs and for owners of castrated dogs it had been more often pro-castration. Nevertheless, owners of both castrated and intact dogs reported low levels of agreement with statements on castration having favourable effects on the behaviour of male dogs at a population level, though owners of castrated dogs agreed one and a half times more often than did owners of intact dogs. These overall low levels of agreement seemingly contradict that in 58% of the castrated dogs correcting behaviour had played a role in the decision to castrate. These 58% of owners reported unchanged or decreased levels of aggression following castration, whereas owners who castrated their dog for other reasons most often reported aggression to be unchanged or increased. Finally, our results indicate that overall satisfaction with dog ownership was higher for owners of intact dogs than for owners of dogs castrated to correct behaviour.

Veterinarian practitioners apparently are an important driver of the owner’s decision to castrate, as they advise owners often and pro-castration. As most veterinarian practitioners are professionals in veterinary care more than in behaviour, this finding merits a warning against a Dunning-Kruger effect, when veterinarian practitioners advise on the likely behavioural outcomes of a male dog’s castration. The Dunning-Kruger effect is a psychological effect that implies an overestimation of competence in areas where one lacks competence [32]. As an example in another advising profession, the Dunning-Kruger effect showed in a group of 94 volleyball coaches who advised high schoolers on the volleyball court. These coaches were compared for their self-reported efficacy scores for coaching abilities. Coaches in the lowest quartile of coaching abilities reported significantly higher efficacy than coaches in the highest quartile of coaching abilities [33]. The Dunning-Kruger effect has been found in a wide range of disciplines and professions [34, 35], and was suggested to affect veterinarian students as well [36]. Particularly as sound scientific data on the behavioural effects of castration are presently lacking [5, 6], the Dunning-Kruger effect could imply an overestimation of competence to advise on behavioural effects of castration and may cause veterinarian practitioners to unintentionally advise too confidently on castration affecting male dog behaviour favourably.

Owners could also be vulnerable to psychological processes affecting their opinions on castration. One such process is cognitive dissonance, which facilitates an individual’s coping with its environment, by aligning information processing and decision taking [37]. It prevents discomfort, by processing information selectively [38, 39]. Namely, information that is in line with held cognitions is processed, but contradicting information is disregarded. For owners who castrated their dog, noticing advantageous outcomes of castration may be less discomforting than noticing disadvantageous outcomes, which would not be in line with the owners’ cognitions. Disadvantageous outcomes that are in discord with the received professional advice could add to the dissonance. Such cognitive dissonance processes could work along the lines of similar psychological processes noted in owners of brachycephalic (‘flat-faced’) obstructive airway syndrome (BOAS)-affected dogs. Over half (58%) of these owners reported that their dog did not have a breathing problem [40], although these dogs were affected and consequently showed symptoms. Also, when buying a new dog, owner-perceived dog health was of lesser importance to owners of brachycephalic breeds than non-brachycephalic breeds [41]. Apparently, these owners recognise their dog’s health issues insufficiently, as it may be discomforting to the owner to realise that their choice of a dog’s appearance affects its welfare negatively. Similarly, if dog owners expect aggression levels to lower after castration, a castrated dog aggressing more would cause psychological discomfort, or dissonance. Noteworthy is the apparent contradiction in how owners opinion on castration affecting aggression levels in male dogs at a population level versus in their own dog. Presumed favourable effects are not reported at a population level, but favourable behavioural effects are reported for owned male dogs that are castrated for behavioural reasons. Logically, this could be due to an actual effect of castration on the dogs’ aggression levels. However, without prospective and observational data, the process of cognitive dissonance cannot be ruled out. To avoid dissonance, owners could be more receptive to information in line with expectations, meaning that especially actions of the dog that are non-aggressive will be registered, remembered and reported. The process of cognitive dissonance may contribute to the common belief that castration is ‘good for the dog’s behaviour’, although this belief presently is unsupported. Owners of castrated dogs could report positive behavioural effects following castration to other dog owners, or back to their advising professional. The resulting unrealistic public optimism about the consequences of castrating a male dog may affect a dog owner’s decision to castrate and this may unintentionally backfire if for instance fear-induced aggression levels rise. Such unwanted behaviour can lead to dissatisfaction with dog ownership, which may compromise the dog’s welfare through increased risk of shelter relinquishment or even euthanasia [25, 26, 27, 42, 43].

Limitations of our study, such as it being based on a convenience sample using online recruitment, imply that causality could not be studied and that our findings likely do not apply to all dog owners, such as becoming clear from our sample including 89% women. Women are often reported to respond at higher levels to survey-based studies, such as seen in a Finnish study on the topic of social class inequalities and health [44] and in a USA-study on non-response in student surveys [45]. For dog studies in particular, a higher percentage of women participants is common also, such as seen in the 93% females of 3,080 participants, with recruitment done online, predominantly using social media [46] and the 91% females of 653 participants, with recruitment done via internet and advertisement cards placed in veterinary hospitals, grooming shops, retailers, etc. [47]. This matters as views on a dog’s (and cat’s) desexing differed between men and women, with men being less likely to be pro-desexing [31]. Our convenience sample was largely gathered via internet, including social media, and these channels were hypothesized to be operated differently by women and men, such as by women using these more for communicating and men more for information gathering (searching) [48, 49].

Even though our findings on this convenience sample should not be extrapolated to the general population of dog owners without taking into account the limitations of our study, it seems that owners of intact and castrated dogs differ in the advice that they received from professionals, as well as in their opinions on the behavioural consequences of castration. Particularly, we underline the need for gathering causal evidence for the behavioural effects of castration through prospective study set-ups as to facilitate optimal advice to owners. Today, population control arguments are less valid grounds for a male dog’s castration in many parts of the world. Several authors stress the importance of individually based advice for owner-dog combinations [6, 31] and only through strong scientific evidence on pros and cons of castration can professionals optimize the provision of such individual advice. Without causal and objective evidence, the common belief that castration is ‘good for the dog’s behaviour’ is an urban legend that spreads readily as it elicits an emotional response, seems plausible and contains practical information or a social moral [50].

We recommend prospective causal study set-ups, rather than the predominantly cross-sectional set-ups that have been adopted so far [9, 10, 11, 12, 13, 14, 21, 22] to upgrade the present knowledge on the behavioural effects of castration in dogs from associative to causal. For veterinarian practitioners particularly, attention to behavioural aspects of castration is recommended. They seem to be consulted most often on the topic of castrating male dogs and may be inclined to overestimate their own competence to advise on behavioural effects of castration, following the psychological processes such as the Dunning-Kruger effect. Particularly in those regions where a dog’s castration is not necessary for population management, careful consideration of the pros and cons of castration for an individual dog regarding its health and behaviour may benefit the dog’s behaviour, relationship with its owner and welfare.

Survey items.

For this survey-based research we determined the advice owners received from three types of dog professionals (veterinarian practitioners, behavioural therapists, behavioural trainers) and owners’ assessments of castration’s behavioural effects and this appendix lists survey items in English.

(DOCX)

Click here for additional data file.

Tables containing detailed Chi-square test output.

We present additional Chi-square test output, including Chi-square values, degrees of freedom and residuals for all performed analyses. In Tables A and C we compare the frequency and the nature of the advice that was received by our complete sample of dog owners (N = 491) between different types of professionals (pairwise comparisons between veterinarian practitioners, behavioural trainers, and behavioural therapists). In Tables B and D we compare the frequency and the nature of the received advice between owners of intact dogs (N = 242) and owners of castrated dogs (N = 249), and the same two subsamples are used to compare the owners’ opinions in Table E. In Table F we compare owner-reported changes in aggression between dogs that were castrated for behavioural correction (N = 145) and dogs that were castrated for other reasons (N = 104). In Table G we compare the general ownership satisfaction of owners of intact dogs (N = 242), owners of dogs that were castrated for behavioural correction (N = 145) and owners of dogs that were castrated for other reasons (N = 104) in pairwise comparisons. In all Tables, each row represents one Chi-square test. The first column of each table contains the Chi-square value and the degrees of freedom, the last column contains the P-value. Counts represent numbers of dog owners and Chi-square residuals are between brackets and identify significant deviations from expected values (i.e. >|2|, in bold).

(DOCX)

Click here for additional data file.

(XLSX)

Click here for additional data file.

13 Feb 2020

PONE-D-20-00127

Possible factors driving dog owners' decision to castrate male dogs - Self-reports of Dutch dog owners on received professional advice, their opinions on castration and behavioural reasons for castrating male dogs

PLOS ONE

Dear Dr Roulaux

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

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Reviewer #1: This is an interesting paper examining the reasons for choosing castration of male companion dogs and its perceived behavioural consequences. The work seems sound but it was problematic not to have sight of the questionnaire, and the statistical approach is very simple and limited. See specific comments below. The paper is generally well written but there are some minor issues with grammar in several places (e.g. “Assumingly,”) – the manuscript would benefit from review from a native English speaker.

Introduction

The specific knowledge gap filled by this study could be clearer. The claim that we do not know the behavioural effects of castration is contradicted by studies cited which examine this.

“why dog owners decide to (not) castrate their male dog” is not helpful wording, suggest “why dog owners decide to castrate their male dog or not”

Methods

Please include a copy of the questionnaire as an appendix or supplementary material – this is normal practice in studies of this type. Currently the reader cannot see the range of reasons presented for castration, for example, which makes review of the paper difficult.

The methods do not describe the collection of any demographic data, yet this data appears in results. Again, we need to see the questionnaire and all aspects of the questionnaire need to be described in the methods.

The statistics are rather simple and very limited. For example, use of Chi square required the collapsing of five point Likert scales into binary categories which seems a shame and represents a loss of detail in the data. By assigning a score based on the Likert scale, many more multivariate analysis options are available which are much more appropriate. Currently no effects of demographics are included in the analysis – then why collect this data? The authors should strongly consider complete re-analysis of their data with more sophisticated techniques, or justify why this is not done.

How were the 491 analysed selected from the total of male dogs? Did this introduce bias?

Discussion

The discussion covers a lot of relevant ground but has two major omissions

(1) Possible bias in the study sample based on online self-selection – this is a major issue with online recruitment

(2) Effects of demographics (which were not statistically analysed)

See: Wonsaengchan, C. and McKeegan D.E.F. (2019). The views of the UK public towards routine neutering of dogs and cats. Animals 9(4): 138, DOI:10.3390/ani9040138

Reviewer #2: The manuscript tackles an important issue. There are many concerns regarding the manuscript.

1) The "introduction" section emphasizes that desexing has predominantly no effect on aggression behavior but misses recent review studies that indicate a beneficial effect of desexing of male dogs in reducing the risk of dog bites and male dog-directed aggression (D'Onise et al., Inj Prev, 2017; Urfer & Kaeberlein, Animals (Basel), 2019).

2) There is neither information on sample size calculation nor on the power to detect differences with the sample obtained.

3) There is no information on how the questionnaire was developed. Is it based on a previously validated instrument? With no specific information on the validity or reliability of the questionnaire, the results are questionable.

4) This is a convenience sample and may not reflect the profile of the owners of dogs in the region. Therefore, with no information on how the sample matches the profile of the population of dog owners, the results might well be biased.

5) Statistical analysis is poorly described and conducted. For instance, there is no need to present Chi-square residuals (tables) we need to know, at least, the p-values associated with each comparison.

6) The presentation of results is confusing and may not reflect actual data. For instance, from table 3, I can see that 10% of owners of castrated dogs agree that castration may have affected aggressive behavior against only 3% of owners of non-castrated dogs. So, beyond the fact that we have almost 30% of missing data for that question and that most owners do not agree, it seems that castration increased the likelihood of a "positive" response (from 3% to 10%), indicating that the experience of castration may have changed the perception of the owner regarding the issue.

7) In any case, it is not very easy to compare different people with different experiences. I may well have not castrated my dogs because my dog is not aggressive or because I simply do not believe in castration for such a purpose. In a counterfactual world, what would be my response if otherwise my dog has been castrated independently of my previous opinion? Of course, this is not represented by the answers of owners of castrated dogs, because these owners might well have decided to castrated their dogs because their dogs were much more aggressive than those of non-castrated dogs. So, comparisons here are not adequate for any causal inference.

8) Results sometimes are interpreted against the facts. For instance, from Table 4, I would say that, compared to dogs castrated for other reasons, dogs castrated for behavioral correction showed a substantial decrease in putative behavior. However, authors prefer to emphasize that "Castrated dog's aggression changes were reported on most as 'no change'."

9) The emphasis on "increased" aggression behavior is not rooted in the data. Increased aggression was the smaller change observed and may reflect just variation of owner perception since it is not based on any objective measure.

Reviewer #3: The article "Possible factors driving dog owners' decision to castrate male dogs - Self-reports of Dutch dog owners on received professional advice, their opinions on castration and behavioural reasons for castrating male dogs" is of interest but some points need to be properly treated to improve the quality of the manuscript.

-The text (specially introduction and discussion) is very extensive and convoluted. It must be fully improved.

-Tables are not properly formatted. They are not self-explanatory and do not contain essential information (P-values and proportions).

-The results of the statistical tests are confusing and present unnecessary information (values deviated from expectation; residuals; test statistics calculated from sample data during the hypothesis test...)

-I strongly suggest that the authors read and adapt the article to the STROBE-Vet guideline. This must be submitted as supplementary material.

https://strobevet-statement.org/

-The study area must be described in detail.

-The studied population should also be better described. What are its characteristics? What is the external validity of the results?

- The authors only mention that "targeted dog owners via websites, social media channels and newsletters directed at dog owners". Such a process should be better described. Based on what has been presented, the representativeness of the sample and the possibility of selection bias cannot be assessed.

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28 Mar 2020

We express our thanks for the constructive comments by the reviewers and yourself. In this letter we explain how we processed these comments and address the issues logically and transparently in the manuscript. We also indicate below where in the manuscript the key revisions can be found.

Additional requirements:

We have adjusted the manuscript according to the PLOS ONE style templates, including those for file naming. Also, we added S1 Appendix with the questionnaire items and provide the data as Supporting Information File - Data.

Reviewer #1:

1. Questionnaire and statistical approach

We now provide the questionnaire items in S1 Appendix.

The reviewer's suggestion is to use more sophisticated statistics to explain our found variation in owner responses (i.e. by multivariate analysis). However, our approach was never to maximally explain the variation in response variates of interest by a preselected convenience set of explanatory factors. The study was not set-up for this, meaning the factors that we could test for associations would be arbitrary and not represent a logical set of candidate explanatory variables. Instead, we wanted to test a set of specific relationships and opted for a simple and straightforward statistical analysis by Chi squares, which suits the (limited) sample sizes. Despite our aim not being to test the effect of demographic variables, we still describe these variables to provide some insight on the participants to our convenience sample. We have added details on the collection of the demographic data in the Methods section (lines 136-139) and on the reason for the inclusion of thereof (lines 128-129).

The choice to collapse five-point Likert scales into binary categories was made for ‘satisfaction with dog ownership’ as answers here were skewed towards (very) satisfied, as made transparent in lines 144-146. Here we follow the approach that we used earlier (Van Herwijnen et al., 2018). The other measurement that we present as binary to our readers regards unwanted behaviour, which in our view is most optimally presented to them as ‘relevant or not’ to the factors we investigated (details are given in the Methods section lines 160-163). The reduction of scales may lead to the loss of some details but produces more reliable statistical outcomes, by avoiding low cell counts, and it fits with categorizations that would be meaningful to people.

The reviewer asked how the 491 entries were selected from the total study sample. These 491 entries are the male dogs in the combined dataset of male and female dogs, which was cleaned as described in lines 177-182. We excluded owners who left crucial questions unanswered, being the dog’s sex and reproductive status and (in the case of castrated dogs) whether or not correcting behaviour was a reason for castration. Furthermore, we excluded owners who indicated that they take care of the dog less than 50% of the time, as they may not have been the primary decision maker regarding the dog’s reproductive status. We also excluded owners whose dog was already castrated at acquisition, as these owners were likely uninvolved in the decision to castrate. Lastly, we excluded owners who had their dog castrated chemically, as we were unable to accurately assess the effect of the chemical castration. As stated above, this was made transparent in lines 177-182

2. Grammar

We adapted the grammar issues, such as regarding ‘assumingly’ for which we thank the reviewer for pointing these out.

3. Specific knowledge gap - Introduction

We added lines 52-55 as to clarify the specific knowledge gap filled by this study. Also, we reworded the sentence on deciding to castrate.

4. Questionnaire items and collection of demographic data

We added S1 Appendix, listing our questionnaire items and provided details on demographic data collection in the Methods section (lines 136-139).

5. Discussion

We acknowledge the effects of online self-selection and now provide more details on this in lines 449-464 and thank the reviewer for the interesting reference which we incorporated in our manuscript.

Reviewer #2:

1. Introduction

We thank the reviewer for pointing out these recent references and have added these to our manuscript.

2. Sample size and power

We added details on our sample size and power calculation to the Methods section (lines 196-201).

3. Questionnaire

The questionnaire is now available as S1 Appendix and information on the development of the questionnaire can be found in lines 117-119 of the Methods section.

4. The sample’s reflection of the dog (owning) population in The Netherlands

Here, the reviewer addresses a very interesting point. The meaningful comparison would be between our study population and the population of Dutch dog owners. Previously, our group tried to find information on the population of Dutch dog owners, e.g. by contacting Statistics Netherlands (CBS), but was not able to find useful facts. We mention the hiatus in the Methods section (lines 126-128). Furthermore, in the Discussion section we emphasize that our findings should not be extrapolated to the general population of dog owners without taking into account the limitations of our study (lines 465-466 and see also lines 449-451).

5. Statistical analysis

We present the P-values in the text and the Tables for each studied comparison. With the Chi-square tests, we present standardized residuals to identify the cells with the largest contribution to the Chi-square test results. We mark residuals |>2| bold as this threshold is commonly accepted as a sufficiently large deviation between observed and expected values (Sharpe, 2015).

6. Results presentation

Indeed, Table 3 presents data on owners’ opinions regarding castration affecting male dog behaviour at a population level. Readers will see that distributions for these opinions differ between owners of castrated and intact dogs. The differences in opinions regarding the population level or the own dog are discussed in the Discussion section (lines 432-442). We have specified more clearly that Table 3 regards opinions at a population level, not the reported effect for the own dog. We have adapted all Tables, so they now present proportions as percentages.

7. Causal inference

We have made more salient in the Discussion section that our study was not set up for making casual inferences (lines 449-451). Our aim was to provide insight into owner received professional advice, opinions on castrating male dogs and behavioural reasons for this decision. We feel these findings indicate the need for prospective study set ups that can provide causal evidence as the reviewer justly points out and we have stressed this need in our manuscript (lines 469-470; 478-480).

8 & 9. Table 4 and owner perception

We have reworded the text hoping to provide more clarity while still reporting our results accurately. Also, we agree with the reviewer that our data may reflect owner perception and consequentially this is one of the main points of the Discussion section (see for example the text starting at line 414).

Reviewer #3:

1. Introduction and discussion

We have shortened and simplified the Introduction and Discussion.

2. Tables and results of statistical tests

We present the P-values in the text and Tables for each comparison. With the Chi-square tests, we present standardized residuals to identify the cells with the largest contribution to the Chi-square test results. We mark residuals |>2| bold as this threshold is commonly accepted as a sufficiently large deviation between observed and expected values (Sharpe, 2015). We have adapted all Tables, so they now present proportions as percentages.

3. STROBE-Vet guidelines

We thank the reviewer for pointing us to the STROBE-Vet guidelines and have applied them where this was possible, as our study regards questionnaire-based research and was not an observational study. Also, we improved recognition of key elements, such as through using words as ‘limitations’ (line 30, 449 and 466) to indicate these sections. Changes made include the direct mentioning of study type in the abstract (line 15) and the mentioning of study limitations (Abstract lines 30-31 and Discussion lines 449-451). We also added a sentence on the lack of conflicts of interests (line 491).

4. Study area

The study area has been detailed further (lines 46-55).

5. Study population

The characteristics of the study population can be found in lines 223-237 and the Discussion provides information on representativeness and external validity of the results (lines 449-451; 465-466) and on selection effects in lines 451-464. In the Methods, we have also provided more details on how the dog owners were targeted (lines 124-126).

With these adaptations made to our manuscript, we expect to have addressed all points raised by the reviewers.

12 May 2020

PONE-D-20-00127R1

Self-reports of Dutch dog owners on received professional advice, their opinions on castration and behavioural reasons for castrating male dogs

PLOS ONE

Dear Dr Pascalle Elise Maria Roulaux

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

==============================

Many thanks for resubmitting your manuscript to PLOS One

It was reviewed by the same reviewers as previously, and they have suggested further changes to the manuscript prior to acceptance

If you could write a detailed response to reviewers, that will expedite review when resubmitted.

I wish you the best of luck with your changes

Hope you are keeping safe and well in this difficult time

Thanks

Simon

==============================

We would appreciate receiving your revised manuscript by Jun 26 2020 11:59PM. When you are ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter.

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Please include the following items when submitting your revised manuscript:

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Simon Russell Clegg, PhD

Academic Editor

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Reviewer #3: All comments have been addressed

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Reviewer #2: Partly

Reviewer #3: (No Response)

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3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #2: No

Reviewer #3: (No Response)

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Reviewer #2: Yes

Reviewer #3: (No Response)

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5. Is the manuscript presented in an intelligible fashion and written in standard English?

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Reviewer #2: Yes

Reviewer #3: (No Response)

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6. Review Comments to the Author

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Reviewer #2: The authors made an immense effort to modify the manuscript to take care of my comments. Although I still cannot entirely agree with some statements and conclusions, I understand that we got into the difficult line between reviewer's necessity and authors' latitude to decide the way they want to show their results to the community. Therefore, I will only maintain two points that I still think are necessary for eventual publication in PLOS One.

1) Regarding sample size, I do not think the text included is neither sufficient nor correct. Authors should be able to calculate the power of the study for detecting, for instance, a difference in a certain proportion, say 10%. Please provide this using standard formula, not references for average differences.

2) Regarding the presentation of results, there was no improvement. In this type of study, in which you have two groups (castrated vs. intact) and proportions as responses, you need a better approach to present results.

As I already mentioned, there is no reason to present deviations from expected values; we just need p-values for each comparison. Table 1 could be seen as three 2-by-2 tables comparing advised or not by a certain professional and being castrated or not. For instance, we can see that 81% of owners of castrated dogs received advice from veterinarians against only 63% of owners of intact dogs, is this difference statistically significant? The same question applies to therapists and trainers. Three comparisons, three p-values, that's all we need. There is no need for presenting deviations, the value of the chi-square or the df. The same applies to all tables.

Reviewer #3: (No Response)

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Reviewer #2: No

Reviewer #3: No

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27 May 2020

Responses to the editor and reviewer are added as separate cover letters.

Submitted filename: Response to Reviewers 1.docx

Click here for additional data file.

5 Jun 2020

Self-reports of Dutch dog owners on received professional advice, their opinions on castration and behavioural reasons for castrating male dogs

PONE-D-20-00127R2

Dear Dr Pascalle Elise Maria Roulaux

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

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Kind regards,

Simon Clegg, PhD

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Many thanks for resubmitting your manuscript to PLOS One

As you have addressed all the reviewers comments, and two of the reviewers are in agreement to accept, I have recommended the manuscript for publication

You should hear from the Editorial Office soon

It was a pleasure working with you, and I wish you the best of luck for your future research

Hope you are keeping safe and well in these difficult times

Thanks

Simon

11 Jun 2020

PONE-D-20-00127R2

Self-reports of Dutch dog owners on received professional advice, their opinions on castration and behavioural reasons for castrating male dogs

Dear Dr. Roulaux:

I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now with our production department.

If your institution or institutions have a press office, please let them know about your upcoming paper now to help maximize its impact. If they'll be preparing press materials, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information please contact onepress@plos.org.

If we can help with anything else, please email us at plosone@plos.org.

Thank you for submitting your work to PLOS ONE and supporting open access.

Kind regards,

PLOS ONE Editorial Office Staff

on behalf of

Dr. Simon Clegg

Academic Editor

PLOS ONE