Teak, one of 44 animals seized from a residence in the Town of Schleswig, scratches herself inside the Lakeshore Humane Society kennel on Aug. 7, 2014, in Manitowoc, Wis. She is one of the seized animals with the most health problems, including numerous tumors, fleas, and prolapsed eye sockets. (AP Photo/Herald-Times Reporter/Matthew Apgar)

The broad category of hoarding has only recently been recognized as a psychiatric disorder. In 2013, it first made an appearance in the Diagnostic and Statistical Manual of Mental Disorders, the global reference book of mental health. But while society seems to be aware of the problem of hoarding objects, animal hoarding, which involves keeping dozens or hundreds of animals under poor and unsanitary conditions, remains under-recognized.

This is not because it is uncommon. Up to 2,000 new cases are estimated every year in the United States. This is likely to be an underestimate, because there is a lack of public awareness that animal hoarding is a condition, and only very severe cases are identified.

This also means that very little research has been done on animal hoarding. In the United States, most has been done by a group of experts called the Hoarding of Animals Research Consortium. But interest in researching animal hoarding has been increasing, including two new studies published this year; one by myself and colleagues in Spain and another in Australia.

A total of 44 animals (23 dogs and 21 cats) were removed from the Rockville Road residence, which also saw 43 cats and one dog removed during a 2013 seize. (AP Photo/Herald-Times Reporter/Matthew Apgar)

From this research, it is clear that this condition appears in, and has similarities across, different cultures. But there are still many aspects of animal hoarding to uncover.

There are a number of symptoms which, when combined, constitute an animal hoarding disorder. A prerequisite is having a large number of animals at home. We have seen cases of only 10 animals to instances when people hoard more than 500 in their homes. Sufferers are unable to provide the minimum standards of care for these animals and will deny or downplay the deplorable conditions they and the animals are living in.

For the animals, there can be severe welfare issues. Most of the animals found in these cases are sick, dirty and covered in  parasites. Many dead animals can even be found when you enter an animal hoarder’s home.

Animal hoarding also can lead to several public health issues in the surrounding environment, including infestations of parasites, such as fleas and ticks, or environment toxicity, such as dangerous levels of ammonia from animal urine in the air that people breathe.

Then there are the hoarders themselves. Animal hoarders live in the same unsanitary environment as their animals, sometimes without a functional kitchen or even a clean bed to sleep in.

The most common profile of an animal hoarder is a socially isolated, middle-aged or older woman who collects cats, dogs or both. However, men or even whole families, with children or other dependent relatives, can be animal hoarders or live in a hoarding situation. Other hoarded species include farm animals and reptiles.

Teak gets checked out by veterinarian Chris Katz of the Two Rivers Veterinary Hospital, left, and Lakeshore Humane Society medical technician Hailey Rogala. The Lakeshore Humane Society is asking the public for donations to help with the care of the animals. (AP Photo/Herald-Times Reporter/ Matthew Apgar)

Early research shows that animal hoarding is often associated with attachment problems to other people, which leads to an excessive attachment to animals. This could be due to neglect or abuse during childhood, as investigations of many of the known animal hoarders have indicated.

Animal hoarding sometimes appears along with other mental disorders, such object hoarding or dementia. A common trait is hoarders' lack of insight or awareness of their situation, and there can also be a certain lack of empathy with other creatures.

Even though the exact cause of animal hoarding needs more analysis, the first steps toward tackling the problem are broadly agreed on by researchers. Earlier detection of cases could come from increasing public awareness of the problem.  A simple change in society’s perception of animal hoarding could save many animals’ lives and prevent severe human and public health consequences.

There also needs to be standard policies for effective interventions when animal hoarding is identified. These need to respond to both the animals and the hoarder’s needs. Currently, only a few states have policies to deal with the disorder.

It’s also important that the hoarders themselves are provided care. Currently, when a case is detected, the animals are removed, but no attention is given to the person. More often than not, hoarders don’t realize that the animals were in poor health and they are likely to soon start hoarding again. These people need individual mental health treatment as soon as possible to prevent the usual evolution of a terrible and long-term condition.

Paula Calvo Soler is a doctoral candidate in anthrozoology at the Autonomous University of Barcelona. A version of this post was first published on The Conversation.