12 Must-Know Signs of a Puppy Mill

Puppy mills can be tricky to spot, but use these 12 criteria to help you spot breeders who aren't reputable.

Updated January 4, 2024
Puppies peeking from behind a fence

Looking for a purebred puppy can be a wonderful adventure, but potential owners are often unaware of the plight of puppy mill dogs. Without asking the right questions, you may end up bringing home a dog from a mill with potential medical and behavioral problems. Keep a list of questions handy to avoid red flags, and don't be afraid to question the sellers extensively.

1. Are They Asking You Deep and Prodding Questions?

Good breeders will quiz you on your lifestyle, habits, and knowledge of their breed to make sure their dogs are a good match. They will also ask these questions to match you up with the puppy in their litter whose temperament is the best fit. They want the best for their dogs and for you. If the breeder doesn't ask you any questions and seems unconcerned about the dog's future, this is most likely a puppy mill.

2. Puppy Too Young

Puppies should not be separated from their litters until they are at least eight weeks of age. If they are separated earlier, they can suffer developmental and behavioral problems. Certified dog behavior consultant Barbara Davis of BADDogs Inc. Family Dog Training & Behavior explains, "These youngsters also may suffer emotional harm because of being separated from their mom and litter too soon, or too abruptly, or any number of random events that can occur in the process of being transferred from the puppy mill to the pet store and onward."

Little puppy dog, looking at the camera behind the wire fence, in a shelter adoption.

Eight Weeks Old

If the puppy is younger than eight weeks and the breeder is eager to sell them right away, you should walk away. Good breeders will allow you to meet the puppies before they are eight weeks old, but they will require you to put down a deposit and will release the puppy to you when they're the proper age to go home with you.

3. Internet Sales

There are reputable breeders who advertise their puppies on the internet. However, they will require application forms, contracts, and other information before they will approve the sale of their puppy to you. They will also almost always require an in-person interview and meet and greet. If you find listings for puppies online that are transactions with no requirements, or offering to ship puppies to you sight-unseen, you should be aware that you are most likely dealing with a mill (or a scammer).

Quick Tip

Do a quick search for their business and see if any reviews pop up. 

4. Pet Store Puppies

According to the Humane Society, in addition to online sales, many pet stores get their puppies for sale from puppy mills. You can ask the store owners and staff where the dogs come from. Do your research online to see if the store has any complaints or bad reviews regarding their puppies.

5. Consider the Housing Conditions 

Puppies should ideally be whelped and raised in a home environment. If the breeder uses a kennel, it should be clean and free of any strong odors of urine and feces. If the breeder will not let you into the kennel area, this is a major sign of concern. On the other hand, if they do allow you to see the kennel and the conditions are dirty, this is also a sign to walk away.

6. Keep An Eye Out For "Dirty" Puppies 

Another common mill dog issue is "dirty puppy syndrome." Davis explains, "If the puppies aren't given a separate space to toilet, and their mom isn't able to keep them clean, they may not develop an aversion to their own poop. This means they can be exceptionally difficult to house train." If you observe puppies at the breeder sitting in their own feces and urine or eliminating right in their living or sleeping area, this may be a mill dog situation.

Need to Know

This issue alone, if the pup is just 'dirty' and it's not a puppy mill, doesn't have to be an immediate no. But you should be aware these dogs could have health problems that need to be cared for immediately. 

7. Ask To See The Puppy Parents

A reputable breeder would not hesitate to allow you to meet the puppy's parents. It's possible one parent may not live on-site if they have mated their dog to one owned by another breeder, but at the very least, the dam should be available as she will be caring for the puppies.

The appearance and personality of the parents are good indicators of what the puppy will be like. If they do allow you to meet the dam and/or sire and the dog appears skittish, fearful, or aggressive, this is a real cause for concern.

8. Be Wary Of Multiple Litters

A good breeder invests time in getting to know their dogs and providing them with ample attention. This means they will only have one litter at a time. Of course, it is possible they may have two breeding pairs.

If they live in the home and the litter is well cared for, this may be a safe situation. If the breeder you are interested in has any of the following, you are probably dealing with a mill:

  • More than one litter at a time or back-to-back breeding of same female
  • Litters of more than one breed at a time
  • A constant supply of puppies

9. Designer Breeds Can Be An Indicator

While this is not necessarily a telltale sign of a puppy mill, if the breeder sells more than one breed, and many of them are designer/cross-breeds or "teacup" and mini versions of breeds, you could be dealing with a mill. These types of dogs are high sellers and popular. Mills tend to produce many of these breeds due to their higher potential for profit.

Need to Know

Not all 'designer' breeds are from a puppy mill. There are some breeders who genuinely adore the cross-breeds.

10. Ask to See Medical Records for the Puppy

There are several critical questions and observations about the puppy's health that can give you clues as to whether a breeder is reputable or not.


Does the puppy have the proper vaccinations? Mill dogs are often not vaccinated.


Are there veterinary records for the puppy that indicate it and the mother have had regular check-ups? Mill dogs usually receive little to no professional care to avoid expenses.

Genetic Screening

Have the breeders done recommended health testing for the adults to make sure they are free of genetic conditions? Do they have proof? Keep in mind that each breed has different recommended screenings for different health conditions.

Overall Health

Does the puppy appear healthy? If you notice problems such as a dull-looking coat, skin conditions or even open wounds or sores, sniffling, and runny eyes, limping, or coughing, this is a puppy that is not receiving necessary veterinary care.

11. Monitor The Puppy's Behavior and Overall Disposition

Young puppies should be generally friendly and eager to meet new people. If you see any behaviors that appear abnormal, this is a cause for concern. Mill dogs often suffer from a lack of adequate socialization. As a result, they can be extremely fearful, shy, or aggressive. You may also observe older puppies exhibiting "stereotypies."

Davis says, "Stereotypies are compulsive behaviors driven by elevated stress; these may include self-grooming, licking of objects, spinning, tail-chasing, pacing, and many others."

12. They Should Ask You to Sign a Contract

A responsible breeder will not let you buy a puppy without signing a contract. These contracts will often include language about returning the dog to them if you cannot keep them, spaying or neutering at a certain age, or "co-owning" the dog for breeding rights. If the breeder simply wants to take your money with no questions asked, this is not a reputable breeder.

Do Your Homework

Remember that getting a dog is a lifetime commitment that can last 10 to 15 years (or more), depending on the breed. If you have your heart set on a purebred puppy, buying one from a responsible breeder means you will most likely be taking home a happy and healthy dog. At the same time, you won't be supporting a puppy mill industry that is well known for a lack of concern for the dogs' well-being.

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12 Must-Know Signs of a Puppy Mill