When “People Who Hoard Animals” was published in Psychiatric Times in 2000, we were just beginning our study of this poorly understood behavior.1 Since then, hoarding disorder (HD) has been a subject of considerable research and has become an official diagnosis in DSM-5. DSM-5 criteria for HD do not specify the types of possessions that are necessary for this diagnosis. Because animals are legally considered property (ie, possessions), the hoarding of animals would appear to qualify as HD, although this question is not yet resolved in the psychiatric literature.
In light of this development, a review of the existing literature and a new look at animal hoarding is warranted. In this article, we provide an overview of what we have learned in the past 15 years about this behavior with respect to phenomenology, etiology, and treatment. At the outset, it is important to note that our knowledge of this condition is based on a limited number of studies. Consequently, what is described here should be viewed as a set of working hypotheses.
Although animal hoarding technically fits the criteria for HD, DSM-5 fell short of listing it as an official subtype, and Mataix-Cols2 has rightly noted that its diagnostic classification remains unclear on the basis of the available evidence. DSM-5 describes animal hoarding as a condition associated with HD and defined by “the accumulation of a large number of animals and a failure to provide minimal standards of nutrition, sanitation, and veterinary care and to act on the deteriorating condition of the animals (eg, disease, starvation, death) and the environment (eg, severe overcrowding, extremely unsanitary conditions).” Estimates from surveys of animal control agencies and humane societies suggest that there are approximately 3000 reportable cases of animal hoarding annually in the US.3
The most dramatic feature of this behavior is the effect it has on the home environment. Large numbers of animals, often sick, dying, or dead, are crammed into living areas of the hoarder’s home. Often urine and feces cover the floors and/or walls, creating high concentrations of ammonia and aerosolized organic contaminants that pose serious health risks to occupants.4,5 In a study of complaints to health departments, animal hoarding was found to result in significantly more unsanitary conditions than did object hoarding and posed significantly more threat to the health of human occupants of the home and to the community at large.6 Surveys of caseworkers dealing with this problem indicate that a lack of appropriate sanitation appears in 70% to more than 90% of animal-hoarding cases, and together with the large number of animals involved, increases the likelihood of zoonotic diseases for the occupants and the community.4,7
Case reports indicate that between 31% and 100% of individuals who hoard animals also hoard inanimate possessions.7,8 In these cases, the clutter and unsanitary conditions severely interfere with normal activities of daily living, such as sleeping in a bed, bathing, finding important objects, and preparing food. Often major appliances, toilets, showers, and tubs are not in working order. Inability to care for the hoarded animals and to maintain basic personal hygiene make this a problem of animal abuse as well as of the hoarder’s self-neglect. From a resource perspective, animal-hoarding cases require more agency involvement for resolution than do object-hoarding cases, and legal proceedings can result in substantial costs.6
Types of animal hoarding
Patronek and colleagues9 have suggested 3 ways to classify persons who hoard animals: overwhelmed caregivers, rescuers, and exploiters. The overwhelmed caregiver is an individual who owns a large number of animals that were reasonably well cared for until a change in circumstances impaired the individual’s ability to provide proper care for them. Most often, the circumstances involve loss of resources, such as death of a spouse, loss of a job, or failing health. These individuals often initially make attempts to provide adequate care but eventually become overwhelmed, and living conditions deteriorate. Their acquisition of animals tends to be passive, with new animals coming from breeding among the animals they have. Overwhelmed caregivers of-ten exhibit some awareness of their problems with animal care and tend to minimize rather than deny them. Isolation may be a factor in their reluctance to seek help. When they are confronted by authorities, they have fewer problems complying with intervention than rescuers or exploiters.
A strong sense of mission to save animals from a presumed threat characterizes the more serious rescuers or those who are mission-driven. These individuals vehemently oppose euthanasia and show strong fears about the death of their animals, even though they fail to recognize the poor quality of the care they are providing. They believe only they can adequately care for their animals. Even as they become overwhelmed, they continue to collect new animals, often relying on a large network of enablers who facilitate their acquisition of more animals. Their acquisition methods tend to be more active than passive, often involving going in search of animals they perceive to be in need of rescue. Mission-driven animal hoarders or rescuers go to great lengths to avoid authorities and actively prevent outside influence over their growing population. These individuals now often present themselves as organized institutional personnel, often masquerading as representatives of a legitimate shelter or sanctuary that cares for hundreds of animals.
Animal-hoarding cases typified by exploiters are the most serious and difficult to resolve. They involve individuals with sociopathic characteristics who acquire animals to serve their own needs, with little true attachment to them. These individuals appear indifferent to the suffering of their animals, and they lack empathy for humans and animals. They display extreme denial of any problems and flatly reject authority or any outsider’s legitimate concerns. As do the mission-driven animal hoarders, exploiters believe their knowledge is superior to anyone else’s, and they display an extreme need to exert control over their animals. Exploiters display many characteristics of antisocial personality disorder, including superficial charm and charisma; they are manipulative and cunning, narcissistic, and appear to lack guilt or remorse. The absence of emotional attachment to their animals suggests that these individuals may not fit the diagnostic criteria for HD.
Dr Frost is Harold and Elsa Siipola Israel Professor or Psychology at Smith College, Northampton, Mass. Dr Patronek is Adjunct Assistant Professor at the Cummings School of Veterinary Medicine, Tufts University, North Grafton, Mass. Dr Arluke is Professor of Sociology at Northeastern University, Boston. Dr Steketee is Professor in the School of Social Work at Boston University. The authors report no conflicts of interest concerning the subject matter of this article.
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