Introduction

Violence against intimate partners, or ex-partners, encompasses a multitude of forms of abuse (psychological, psychological-physical and psychological-physical-sexual). The context in which this violence takes place is usually the family or domestic sphere, so the violence will be more concealed, or covert, than other types of crime (Acosta, Acosta & Vilda, 2000). In addition to the fact that the aggressor harms the partner, or ex-partner, with violence, as well as other family members such as the children; pets should also be taken into account, as they are present in many homes and can be used by the aggressor as an indirect instrument of abuse against the partner (Blaney et al., 2021; Caravaca-Llamas, 2022; DeGue & DiLillo, 2009; Jordá-Sanz & Janosch-González, 2022; Mota-Rojas et al., 2022).

To explain this phenomenon, the research has focused on the, ‘Hypothesis of the Graduation of the Violence’ and the ‘Deviance Generalization Hypothesis,’ (Cleary et al., 2021). The first hypothesis refers to the fact, that those aggressors who start by harming animals may well start to be violent in the future with people (Arluke et al., 1999). Another more recent hypothesis, relates vicarious violence, understood as the violence that is perpetrated when the aggressors no longer have direct access to the victim and take it out on what they still have access to, as a way to continue abusing the victim. This violence, therefore, acts against meaningful third parties in order to harm the principal victim (Porter & López, 2022). Unlike the ‘Deviance Generalization Hypothesis’, whereby this type of behavior is one of the many behaviors that an antisocial person can present without an established order (Frick & Viding, 2009).

In general, abuse of pets in these cases is carried out following arguments between the aggressor and his partner, where the animal is deliberately harmed by the aggressor in an attempt to punish the victim or to gain power or control over them (Jordá-Sanz & Janosch-González, 2022; Levitt et al., 2016). Furthermore, the aggressors usually aim to intimidate and exercise psychological control over their victims through the fear generated by harming the pets (Alleyne, 2019; Faver, 2003; McDonald et al., 2015). Pet owners are usually afraid of something happening to them (Ascione, 1998; Faver & Cavazos, 2007) and/or they are usually worried about themselves and their needs (Barrett et al., 2018), leading to an affectionate relationship with the animal and consider them part of the family (Arahori, 2017). Furthermore, studies have shown the importance of the relationship with a pet. For example, the relief from the loneliness to its owners by feeling less alone (Pikhartova et al., 2014) or that they provide the pet owner with the necessary support to be able to withstand abusive situations (Fitzgerald, 2007) This support can strengthen an emotional bond between them (Lass-Hennemann et al., 2022).

For all of the above, the main objective of this review is to analyse the presence of animal abuse in cases of intimate partner and domestic violence and to examine the extent to which the affective relationship with their pets influences the victims with respect to fleeing the aggressor and leaving their homes.

Method

This systematic review was carried out following the Prisma Methodology, “Preferred Reporting Items for Systematic Reviews and Meta-Analyses”.

Eligibility criteria

We used the following criteria to determine whether studies were eligible for inclusion: (1) any original articles, published as full papers published in a peer-reviewed journal; (2) Being accessible with the keywords, “animal abuse, domestic violence and intimate partner violence” in reliable databases (Web Of Science, ScienceDirect, Scopus, Pubmed or Google Scholar); (3) all those articles published between 2013 and 2023, (4) Studies published in English or Spanish.

We discarded reviews, theses or dissertations, as well as works from degrees and post-graduate degrees. In addition, all the articles whose titles made no mention of the objective of this research or the established key words were directly excluded. The articles had to deal with animal abuse as one of the consequences of domestic violence and intimate partner violence.

Search strategy

The search for articles to include in the review was carried out in the Web Of Science, Science Direct, Scopus, Pubmed and Google Scholar, for articles from the last ten years.

Eligibility criteria were kept comprehensive to encompass as many empirical studies as possible. The algorithm used for papers in each database was as follows: e.g., Search “Intimate Partner Violence” [OR] “Domestic violence” [AND] Animal Abuse” [OR] “Pets abuse”. The references of eligible studies were also searched using a snowballing technique, where we searched within the selected articles that had been filtered by the inclusion criteria for other articles that could meet the objectives of the study.

Having obtained a total of 138 results, we proceeded to eliminate those that were repeated or duplicated; due to finding the same article in different languages or to finding the same work in different databases. Following this step, we had a total of 32 articles, of which only 9 passed the established inclusion filters.

In order to decide whether these nine articles were finally adequate for the review in question, their quality was measured using the Newcastle-Ottawa scale (Wells et al., 2022). This scale consists of a qualification system to compare studies based on such factors as design, analysis or presentation. Having checked the quality of the articles, we then proceeded to a complete, exhaustive reading of the selected articles in order to take a final decision.

This complex process of identification, search and inclusion is clearly set out in the diagram of Fig. 1.

Fig. 1
figure 1

Flowchart diagram of the study screening and selection process. Note: PRISMA flow diagram of systematic search and study selection according to Page et al. (2021)

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Data extraction and analysis

A series of data were extracted from each of the articles: authors’ names, date of publication, the country where the research took n place, objective of the study, number of participants including average age and gender of the sample, the percentage of the sample with children, means of access to the sample, study design, type of violence suffered, most frequent gender of the aggressor and the motive for the aggression, type of pet abused, instruments used to measure the results, and direct and indirect consequences of the abuse.

Results

An analysis of the reviewed articles is available in Tables 1 and 2 shown below.

Table 1 Objectives of the research works, population and evaluation instruments
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Table 2 Type of violence and consequences for the victim and the pet
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Description of the results concerning the main data of the reviewed articles

As far as the objectives of the works of research are concerned, the results reflect that all the articles investigate the relationship between domestic violence and animal abuse of pets in the home, as well as the consequences this situation has for the persons suffering the abuse. Some of the research articles qualify the situation of the minors and their role in this abusive scenario as further victims of domestic violence (Barret et al., 2018; Haden et al., 2018; Hartman et al., 2018).

The samples used in the articles range from 503 (Riggs et al., 2021) to 42 (Haden et al., 2018). Women significantly predominate as the victims in these studies, and the scarce number of males in the samples of the reviewed works was because the only samples with males was made up of perpetrators with a history of animal abuse (Haden et al., 2018), or who were attending an intervention programme for abusers (Febres et al., 2014). The age of the victims that made up the sample, ranged between 14 and 68 (Herbert, 2020), where the average being 48 and only one child. Concerning access to the sample, it must be stressed that practically all the women participating came from programmes for victims of intimate partner or domestic violence, or from shelters or agencies that provide a safe haven for these victims until the situation can be solved. The exceptions, of course, were the studies that selected males as the study sample (Febres et al., 2014; Haden et al., 2018).

Finally, the instruments used to measure the results of the works included several previously created questionnaires. It can be seen that some are used repeatedly, such as the CTS2 “The Revised Conflict Tactics Scale” (Barret et al., 2018; Fitgerald, 2019; Haden et al., 2018; Hartman, 2018), the PTS “Pet Treatment Survey” (Collins et al., 2018; Hartman et al., 2018), or the BPSS “Battered Partner Shelter Survey” (Hartman et al., 2018).

Description of the results with respect to the characteristics and consequences of abuse

We now set out the principal results extracted concerning the impact of animal abuse in the context of intimate partner and domestic violence, as they are reflected in Table 2 below.

It can be seen that the most reported type of violence present in the reviewed articles is that of physical violence (Barrett et al., 2018; Collins et al., 2018; Febres et al., 2014; Fitzgerald et al., 2019; Giesbrecht, 2022; Haden et al., 2018; Hartman et al., 2018; Herbert, 2020; Riggs et al., 2021), followed by psychological violence (Barrett et al., 2018; Collins et al., 2018; Febres et al., 2014; Fitzgerald et al., 2019; Giesbrecht, 2022; Haden et al., 2018; Hartman et al., 2018; Herbert, 2020). Sexual violence, however, also has a high prevalence (Giesbrecht, 2022; Haden et al., 2018; Hartman et al., 2018; Herbert, 2020; Riggs et al., 2021), although it is not as frequent as the other two mentioned above; while only one article describes abuse due to sexual identity (Riggs et al., 2021). Furthermore, it highlights the low prevalence of economic violence as another form of mistreatment towards people who suffer violence (Giesbrecht, 2022; Riggs et al., 2021).

As for the most frequent gender of the aggressor, it is males in all the reviewed articles, except for two (Barrett et al., 2018, Riggs et al., 2021) that speak of intimate partners without specifying sex or gender identity. In the cases where men appear as the aggressor, the works of research have found that, in most cases, the violence is perpetrated in order to cause harm and suffering to the partner. The desire for power and control on the part of the aggressor is also mentioned, as well as to humiliate and dominate all the members of the nuclear family, whether that be pets, or women and children (Collins et al., 2018; Hartman et al., 2018). As for pets, although there may be different types, cats and dogs are the principal ones found in the samples of the selected studies. Although not all the articles describe the specific typology of animal abuse in depth, there are references to what is most predominant; that is, physical abuse, while neglect/abandonment and threats also occur (Febres et al., 2014).

Finally, the consequences that are reflected in the articles included in the review are also mentioned. The said consequences refer to how this violent situation affects the woman, as well as how it affects the children and pets. First of all, the most commonly found consequences are the victim’s emotional harm and serious mental health problems, provoking such problems as depression, and fear or anxiety for both human and animal victims (Herbert, 2020). Most of the victims feel manipulated (Giesbrecht, 2022) and abused, both physically and emotionally. Delaying leaving home is another of the most commonly mentioned consequences, due to the fear of possible retaliation on the part of the abuser (Barret et al., 2018; Giesbrecht, 2022; Herbert, 2020).

Such retaliation may be directed towards her or towards the pets that live in the home, with the abuser threatening to harm the animals, so the woman decides not to leave as she fears what may happen to her pet if she leaves it behind, since she cannot take it to the shelter (Barret et al., 2018). This same fear also often means longer delays in asking for help (Barret et al., 2018; Hartman, 2018), attempting to endure as long as possible, hoping the situation will change, and fearing the consequences if the abuser finds out that she has asked someone for help. Concerning the consequences, special mention is also made of the children, who can develop serious behavioural problems, and even replicate the behaviour patterns of abuse when they reach adulthood (Collins et al., 2018; Haden et al., 2018). Their mental health can also be seriously affected from being constantly exposed to this type of violence from a very young age (Herbert, 2020).

Discussion

The current bibliographic review offers an update on the relationship between intimate partners, the evidence of domestic violence and animal abuse, in a wide variety of contexts and from different perspectives.

Castro et al. (2009) and Barraza and Turcios (2022) point out that domestic violence is that which occurs in the context of a family, carried out by the partner or ex-partner of the victim, independently of the gender of the victim or the aggressor. Nevertheless, Alberdi and Matas (2002) consider this term to be ambiguous as it does not make clear the gender of the aggressor. However, starting from the reviews carried out of the selected articles, it can be stated that domestic violence almost exclusively affects women and that the aggressor, in the great majority of cases, is male (Collins et al., 2018; Febres et al., 2014; Fitgerald, 2019; Giesbrecht, 2022; Haden et al., 2018; Hartman et al., 2018; Herbert, 2020), except for two studies in which male victims were also referred to in percentages ranging from 1.7 to 27.5% (Giesbrecht, 2022; Herbert, 2020). However, there is other research that suggests that both men and women are alternatively victims and perpetrators (Mathes, 2015). It is also necessary to state that the sample used in the studies, which selected aggressors instead of victims were made up of 100% males (Febres et al., 2014; Haden et al., 2018). In these articles, we can find such predictors of aggressive conduct towards the partner as animal abuse; although also antisocial personality traits and alcohol abuse are also present (Haden et al., 2018; Febres et al., 2014). This latter predictor coincides with other works of research that state that aggressions occur when the abuser returns home drunk (Newberry, 2017).

One of the weapons abusers use for coercion and to prevent the partner, or even other members of the family, from asking for help or even from leaving home, is violence against the pets (Barrett et al., 2018; Giesbrecht, 2022; Hartman et al., 2018; Herbert, 2020). Some studies, such as the work of Newberry, describe how abusers use pets to hurt the woman. Most of the studies only make short references to cases where diverse forms of abuse can be observed, such as control (Barrett et al., 2018; Fitzgerald et al., 2019; Haden et al., 2018; Herbert, 2020; Riggs et al., 2021), manipulation (Giesbrecht, 2022), or punishment of the pets (Collins et al., 2018; Hartman et al., 2018). In over half of the results, it is only indicated that the threats and aggressions aimed at pets occurred just before the physical or psychological aggression towards the victim (Herbert, 2020). However, the majority of the studies do not specify where the victim was during the abuse of the pet, except for two articles (Herbert, 2020; Levitt et al., 2016). In general, we have been able to verify that the works of research focus more on how animal abuse is used as a form of domestic violence than on the aggressions aimed at the pets themselves (Giesbrecht, 2022).

The reviewed articles demonstrate that most aggressions towards pets were in the form of physical abuse (Barrett et al., 2018; Collins et al., 2018; Febres et al., 2014; Fitzgerald et al., 2019; Giesbrecht, 2022; Haden et al., 2018; Hartman et al., 2018; Herbert, 2020; Riggs et al., 2021), followed by emotional abuse (Barrett et al., 2018; Collins et al., 2018; Febres et al., 2014; Fitzgerald et al., 2019; Giesbrecht, 2022, Herbert, 2020; Riggs et al., 2021), or privation of food and water or other types of care, such as hygiene or veterinary assistance (Febres et al., 2014; Giesbrecht, 2022; Herbert, 2020; Riggs et al., 2021). Some studies show that the abusers not only mistreated their own pets; but also did so to neighbours’ pets, strays and, in some cases, also participated publicly in acts of cruelty against animals (Herbert, 2020). The most commonly domesticated pets are namely dogs and cats; although there are other types of pets that also suffer mistreatment, such as rodents or birds. However, what is clear is that pets are invisible victims of domestic violence, for which specific measures must be taken as set out in the review by Randour et al. (2023).

Animal abuse is directly related to the fact that women who are victims of domestic violence delay leaving their home and do not ask for help, as they fear that they themselves or their pets will suffer reprisals from the aggressor (Barret et al., 2018; Giesbrecht, 2022; Hartman et al., 2018; Herbert, 2020). This situation could be aggravated by the fact that, as pointed out by several researchers, shelters for these women who are looking for protection cannot take their pets with them if they go, so they are forced to leave their pets in their homes, exposed to all sorts of dangers (Ascione et al., 2007; Barret et al., 2018; Gallagher et al., 2008). The existence of this problem can be corroborated with the recent creation of VioPet (Reyes, 2023), a programme created in Spain to cover this need in some way. It is an initiative by which temporary or permanent foster homes are offered for the pets of abused women, for as long as they remain in the shelters for victims of violence. Thus, these women are assured that their pets will be safe during the time they are absent from their homes.

A limiting aspect of this review is the use of the terms domestic violence and intimate partner violence. On performing the review, the variability of the terms used depending on the country where the research is being carried out is evident and can lead to confusion. Abreu (2006) points out that intimate partner violence and domestic violence are not the same. Jaramillo & Canaval (2020) use intimate partner violence to refer to gender-related violence; while Ocampo Otálvaro & Amar Amar, (2011) indicate that intimate partner violence in the literature is known as domestic violence. The fact that these terms are used in different ways in different countries can also contribute to the inaccuracies pointed out by some authors. For instance, the term domestic violence is not easily found in the Spanish literature; since, in general, the term gender violence is more commonly used to refer to what other countries call domestic violence (Hernández, 2022; Jordá-Sanz & Janosch-González, 2022). This exemplifies the variability of the terms, yet all the articles in this review use the terms widely known as intimate partner violence and domestic violence.

For this review, we have excluded articles where, the researchers collected data, using uncommon methods to collect information despite the fact that their authors have been very methodical in the collection of information, such as criminal records or internet forums (Hardesty et al., 2013, Levitt et al., 2016; Newberry, 2016). If these had been included, other data could have been obtained, but we do not consider that they could be grouped with the data for this review. In addition, for future research in this field it would be advisable to search other databases such as Medline (Ovid), ProQuest, and Wiley Online Library to maximize possible results. Finally, the difficulty in finding studies referring to this topic is significant. One of the reasons for the absence of qualifiable data may be that even in our society, animals are not considered to have the capacity to possess legally enforceable rights in and of themselves (Jowitt, 2020), and the prevention of them from accessing the accommodation for women victims of violence where their owners shelter. This is why it is recommended to carry out more research in this field of knowledge to ratify the data provided by this review or, in contrast alternative data be observed.

Conclusions

From the results of the systematic review carried out, it can be concluded that the aggressors, in order to hurt the women who are their victims in cases of intimate partner violence and domestic violence, mistreat the pets in their home, making them the victims that are largely ignored by the associations and the public administration.

Regarding domestic violence, it can be confirmed that it is a fact which affects all societies throughout the world and has numerous victims involved, mainly women, their pets and/or the children of the victims who can put their own integrity at risk in an attempt to protect their mothers and their pets from harm by the aggressor (Ascione et al., 2007). It is also advisable to make special mention of the covert behaviour of economic violence, which is mentioned in some articles of the review and which there is minimal investigation and research in its relationship with domestic violence. It could be beneficial to societies if more emphasis were placed on investigating this relationship since it appears to have devastating consequences for the victim and could be a reason for her or her pet not leaving the family home (Stylianou, 2018).

Despite the creation of initiatives to try to solve this situation, they have not been sufficient, as laws could have been passed allowing pets to accompany women in the shelters, where the pets could act as a real emotional support for them (Hardesty, 2013). Added to this problem are the stress that the victims of domestic violence suffer and the worry from having to leave their pets in an unknown place with someone they do not really know. Nevertheless, the public administration currently has no adequate spaces for both victims (women and pets) to live together in companionship. This is because the animals need space and additional specific measures of cleanliness; besides the fact that they can disturb other women due to noise or allergies. However, we hope that this work can serve to demonstrate some of the other needs that victims of violence have, so that the shelters, or any other similar entity, can put into practice the necessary measures and can redesign their rules concerning the admission of pets.