What Is a Puppy Mill? Why Are They Bad for Dogs?

A puppy mill is essentially a large-scale, high-volume commercial dog breeding operation with the primary goal of profit rather than animal welfare. The puppies who come out of puppy mills are often plagued with diseases and health issues, while the adult dogs who live out their lives in the facilities are forced to breed as often as possible.

Stores that rely on puppy mills as part of their business models do so because they want to keep their display cases full at all times. It’s no coincidence that these stores don’t reveal any substantial information about where the dogs came from—and especially the conditions to which the puppies and parent dogs are subjected.

What Is a Puppy Mill?

Puppy mills, sometimes referred to as “factory farms” for dogs, focus on producing the highest number of dogs as quickly and as cheaply as possible. These commercial breeders are characterized by small cages that are often stacked on top of each other to maximize space, dirty living conditions that facilitate the spread of diseases, minimal or poor veterinary care to reduce operation costs, and lack of basic needs like grooming, exercise, or socialization.

In most puppy mills, female dogs are bred at every opportunity, regardless of if they are sick, injured, or possess genetic traits that may be passed down to offspring. According to the Humane Society, there are over 200,000 dogs kept solely for breeding purposes in active USDA-licensed puppy mills throughout the United States. Each year, 2 million puppies sold in the U.S. originate from puppy mills.

Puppy Mills vs. Breeders

Unfortunately, responsible breeders and puppy mills can be hard to differentiate on the surface, especially when buying online or from advertisements. Because of this, learning to recognize the difference between a puppy mill and a responsible breeder typically comes down to the buyer.

As a general rule, anyone wanting to buy from a breeder should not only meet the breeder in person, but also meet the parent dogs and see the breeding facilities with their own eyes—paying special attention to factors like hygiene and whether or not the animals look frightened, antisocial, or unhealthy.

A responsible breeder will also introduce potential buyers to at least one parent of the litter and have background documentation ranging from health records to referrals from veterinarians and past customers. They’ll also want to know more about a buyer to ensure that their animals are going to a good home, ask for references from vets they have used in the past, and even ask to visit their home.

Good breeders often have long waitlists for their puppies—a sign that they give the mothers adequate time to recover after giving birth and provide puppies with the appropriate amount of weaning.

The Humane Society and the ASPCA both have printable checklists available for potential buyers to bring along when visiting breeders to ensure that they’re running responsible operations.

Why Are Puppy Mills Bad for Dogs?

In order to save on operation costs, animals in puppy mills are often kept in small cages with dirty living conditions that can lead to diseases, lifelong health issues, poor veterinary care, and minimal social skills.

Poor Conditions

Puppies from puppy mills are regularly taken from their mothers at a young age before they’ve had the chance to form important social skills and be fully weaned. According to the ASPCA, puppies should stay with the mother until they’re at least 8 weeks of age and, ideally, should be placed when they are between 10 and 12 weeks old.

A 2020 study in the journal The Veterinary Record found that one-quarter of all puppies in the United Kingdom were acquired before 8 weeks old, even despite recommendations of veterinarians, animal welfare organizations, and even legal restrictions.

Since puppy mills are only concerned with breeding the most puppies using the cheapest methods, often only injuries and disorders that could affect a dog’s reproductive capabilities are treated. Puppy mill staff members may even be expected to perform veterinary care without a proper license.

Health Problems

Common veterinary issues among dogs from puppy mills include infectious diseases, intestinal parasites, respiratory issues, skin disorders, ear problems, hypoglycemia, brucellosis, and congenital defects. The lack of preventive veterinary care and general oversight paired with unsanitary conditions can cause even minor injuries or health issues to linger and cause premature death in the animals.

Some of these health issues can spread to humans. In 2019, the Centers for Disease Control and Prevention (CDC) investigated an outbreak of antibiotic-resistant infections that affected at least 41 people across 17 states (nine of whom were hospitalized). The outbreak was eventually connected to Petland, a chain of pet stores with multiple locations around the United States.

Socialization and Anxiety

Because of how these animals are housed, weaned, transported, and eventually homed, puppies that are born in puppy mills often have behavioral issues as well as health issues. This is especially true in puppy mill dogs who are taken from their mothers without enough maternal care, including grooming and nursing the puppies. This bonding process between puppies and their mothers plays an important role in the social development of the puppies. Newborn puppies have a limited capacity for movement, so maternal interaction is essential to their survival, nourishment, and protection.

Many of these problems can present themselves later in life and well into adulthood, having profound and long-lasting effects on both dogs and their owners. In 2017, a consolidated analysis of seven different studies for the Journal of Veterinary Behavior found that 86% of reports listed aggression directed toward the dog’s owners and family members, strangers, and other dogs as the most common finding among dogs sold through pet stores or born in puppy mills.

This behavior can lead owners to surrender their dogs to a rescue center, helping contribute to the 6.3 million companion animals that enter animal shelters in the United States every year.

An ASPCA survey found that 46% of people who rehomed their pet in 2015 did so because of problems with the animal, the most common of which were aggression (35%), destruction (29%), and health problems (26%).

Overbreeding and Inbreeding

Overbreeding happens when an animal is forced to breed more than its body can safely handle. Intentionally overbreeding certain breeds, such as flat-faced dogs like french bulldogs and pugs, has been linked with specific health issues, like vision and breathing problems. One study of 93 flat-face breed dogs showed that excessive pressure of breeding selection led to the extreme conformation of skull shapes and facial alterations that could put dogs' vision at risk.

Inbreeding in order to maintain a particular “look” of a popular dog breed is also common in puppy mills. Apart from creating exaggerated physical features, inbreeding can lead to metabolic problems, loss of genetic diversity, poor growth, and negatively impact the lifespan of individual dogs.

Are Puppy Mills Legal?

When it comes to federal law, the Animal Welfare Act (AWA) is the only law that’s designed to enforce the humane treatment of animals bred for sale. Conditions under the AWA are essentially designed for the survival of the animal, however, so the standards are incredibly low.

Although many pet stores purchase puppies from commercial breeders who are licensed by the USDA, that doesn’t necessarily mean the animals are kept in humane conditions.

“The Animal Welfare Act provides for some very minimal protections for dogs in certain puppy mills, but the standards of care for these dogs are survival standards at best,” John Goodwin, senior director of the Humane Society of the United States’ Stop Puppy Mills campaign, told Treehugger. “A USDA licensed dog breeder can keep a dog in a cage that is only 6 inches longer than her body, can breed her every heat cycle until her body wears out, and can kill her when she is no longer a productive breeder. This is entirely legal and it’s these puppy mills who fill pet store display cases with the animals they have bred.”

It isn’t just the standards of the living conditions that are low, but the AWA’s enforcement as well. “If a facility wants to sell puppies wholesale to businesses—like pet stores or via websites—it needs to be licensed by the USDA. However, the USDA is currently failing to enforce this law, making its intended protections for animals meaningless,” said Ingrid Seggerman, senior director of federal affairs for the ASPCA. “Puppy mills exist because the retail sale of puppies is still legal in many states, providing an outlet for puppy mills to continue selling dogs kept or raised in unspeakable conditions, far from the public eye.”

The USDA is responsible for inspecting breeding facilities and enforcing the AWA through a branch of the government called APHIS, or the Animal and Plant Health Inspection Service. A report conducted by the Office of the Inspector General in 2021 revealed that APHIS “did not consistently address complaints it received or adequately document the results of its follow-up,” and concluded that “APHIS is not able to ensure the overall health and humane treatment of animals at these facilities.”

How to Avoid Supporting Puppy Mills

The best way to avoid inadvertently supporting puppy mills is by adopting a dog from your local shelter, but if you do end up purchasing from a breeder, keep a lookout for red flags. The Companion Animal Protection Society also offers forms to register complaints about pet shops and breeders.

You can also be sure you're not supporting a puppy mill operation by following these steps:

• Adopt from a local animal shelter or rescue.
• Avoid buying puppies from pet stores (unless they’ve partnered with a local shelter), newspaper ads, or online ads.
• Visit your potential breeders in person and see the facility where dogs are bred and kept with your own eyes.

Avoiding puppy mills doesn’t have to stop there. It’s also important to support legislation that puts a stop to harmful commercial breeding operations. In June 2021, for instance, the ASPCA filed a lawsuit against the USDA for not enforcing the AWA, gathered over 130,000 signatures on a petition, and asked Congress to pass measures to reform the USDA’s enforcement of the AWA.