Common Health and Behavior Problems in Puppy Mill Dogs

Adopting a former puppy mill dog can present a challenging adjustment period. Learn which behavioral and health problems you might expect.

Puppy mill dog health problems
Cute puppies on the internet often come from puppy mills. By Kristine Lacoste/Pets Adviser

You’ve decided to adopt a dog, but not just any dog.

A local rescue group picks up dogs when puppy mills are shut down, and you’ve decided to wait for one of those. The day comes and your dog is ready. What can you expect? There are many puppy mill dog health and behavior problems that you might encounter.

Behavior Problems

The first thing to realize is the environment of the puppies and dogs in puppy mills. Most often they are in small cages that may not allow them to turn around, or they are in a pen with many other dogs. They may not have had any socialization with humans other than quick handling or during transport to another area for breeding.

Many times puppy mill dogs live their entire lives in small cages with wire floors; the wire allows waste to pass through for easier cleaning. You read that right; someone designed a containment method so the dog cannot even relieve itself somewhere else.

The dogs live in filth and waste with the typical cleaning method being a pass with a pressure washer (sometimes without care for the dogs; they have been known to lose an eye to careless washing).

Living in these cages prevents the dogs from experiencing different surfaces such as tile floors, carpet or even grass. In many cases they never see the sun because they live in dark warehouses or outbuildings. As the new owner of a former puppy mill pet, you’ll need to be aware of these aspects in order to understand why your dog exhibits certain behaviors.

Behavior problems are expected and can appear in many forms in puppy mill dogs:

  • Fear
  • Trembling
  • Shyness
  • Aggression
  • Anxiety
  • Food aggression
  • Difficult to house break
  • Difficult to leash train
  • Lack of height or depth perception
  • Light sensitivity or avoidance
  • Surface sensitivity or avoidance
  • Hoarding (food or items)
  • Erratic sleeping pattern

When adopting or fostering a puppy mill dog, assume that your dog’s former environment was a worst-case scenario. Your new pet may exhibit all of the above signs, some of them or none at all. Being prepared and patient is the key to helping your dog relax and become accustomed to a typical home.

Working with your veterinarian and a trainer (if possible) can help you find ways to work with your puppy mill dog and the issues you recognize.

Puppy Mill Dog Health Problems

Remember those wire-floored cages mentioned earlier? The dogs can have their legs fall through those, their nails may become overgrown around the wires, and a host of other problems can be caused by the absence of mobility. The dogs are fed cheap food, assuming meal times aren’t missed. Their water is dirty and can be a breeding ground for mosquitoes and algae.

Waste can accumulate for days, creating the perfect environment for flies, infections and other gross things. Imagine the level of ammonia that must circulate within just one day. Sadly, many puppy mill dogs will live their entire lives like this. They even breed in these conditions.

This doesn’t even scratch the surface of the other health issues your dog might have encountered. Given that there is no vet care or regular grooming, the list of afflictions is long. Puppy mill dog health problems can include:

  • Epilepsy
  • Kidney and heart disease
  • Joint disorders such as hip dysplasia and luxating patellas
  • Endocrine disorders (diabetes, hypothyroidism, hyperthyroidism)
  • Blood disorders such as anemia or von Willebrand (blood doesn’t clot)
  • Deafness
  • Blindness
  • Eye problems such as cataracts, glaucoma, retinal atrophy
  • Shortened or missing limbs
  • Respiratory disorders
  • Matting
  • Mange
  • Mites
  • Scars
  • Periodontal and gum disease
  • Nail overgrowth or growth into the paw
  • Missing teeth
  • Heartworms
  • Fleas and ticks
  • Intestinal parasites

Despite this list of potential concerns, puppies from a puppy mill can appear as healthy and happy as a puppy from a responsible breeder — for a short time.

One story that sticks with me involves a family in the United Kingdom who had lost their pet. After about a year of grieving they finally decided they were ready for another dog. They found a puppy on the internet, met the “breeder” at a neutral place and took their new puppy home. Within a few days the puppy was in severe pain and showing signs of illness. The puppy ended up having parvovirus and had to be euthanized shortly thereafter.

These conditions (and many more) can be present in puppies:

Again, working closely with your vet and a trainer can greatly help your former puppy mill dog recover, heal and adjust to life outside of the nightmare from which they were saved.

While this may all sound pretty horrific for the life of a dog, it happens every day. American breeders with licenses from the USDA rarely get inspected, and the care requirements are grossly inadequate. Some of these dogs have AKC-registered parents and may come with their own prestigious-looking certificate, but a piece of paper cannot replace loving and responsible breeders.

If you are looking for a dog, please consider a rescue. While puppy mill rescues may offer additional challenges, consider the life-changing transformation of which you can take part. If you’re unsure whether a breeder is a puppy mill, please read and share this article as well as our puppy mill red flags article.

Remember: No demand = no profit for puppy mills. 

Until the government regulates and enforces these businesses online and locally, please join Pets Adviser in the fight to reduce their demand. Sign up for free updates on this issue as well as our twice-monthly email newsletter:


One last thing: Check out the photo and the caption below.

"Pets for sale" websites can appear harmless. Would you ever suspect that the owners of this website were running a puppy mill? They were charged in November 2012 with 723 counts of cruelty. Click to see their website as it once appeared.
“Pets for sale” websites can appear harmless. Would you ever suspect that the owners of this website were running a puppy mill? They were charged in November 2012 with 723 counts of cruelty and later pleaded guilty. Click here to see their website as it once appeared.

Additional Resources


Also Popular

Join the Conversation