There is nothing cuter in the world than a puppy — all silliness and romping, waggy tail and pouncing.

When you head to the shelter or a breeder to pick the perfect pup, it can be oh-so-tempting to come home with two. After all, if one puppy is so awesome, wouldn't a pair just be double the fun? Plus, they can keep each other company and be BFFs when you're not around. Sounds like a win-win.

Not a chance, say canine behaviorists and trainers. Bringing home two puppies can almost always result in something known as littermate syndrome.

"When you get puppies from the same litter, they've already bonded to each other," says certified canine trainer and behaviorist Susie Aga, owner of Atlanta Dog Trainer. "Then it's really tough for them to bond with you. It's usually not a great idea."

Aga says she works with many clients who have adopted littermates and have struggled because the dogs won't listen and can be difficult to train. They rely on their canine friend for companionship and comfort instead of their human family.

Some of the most common signs of littermate syndrome include:

  • Difficulty with obedience and training
  • Extreme anxiety when separated from each other
  • Aggressiveness toward each other (especially if it's two female dogs)
  • Fear of strange dogs and people
  • Fear of anything new

Why it doesn't work

two puppies playing in the grass Training? Nope. These puppies aren't listening to you. (Photo: Adya/Shutterstock)

People often get two puppies because they feel guilty that they won't have the time to spend with their new four-legged family member. They think that adopting two pups will give them the constant companionship they need.

This can be a problem on a couple of levels, say dog behavior experts.

First, puppies are a lot of work. Potty training alone takes a ton of time. Having two puppies might make for more restful nights, but it just means double the time spent training your new charges to potty outside. It also means twice the time spent teaching obedience commands and basic manners.

Those early weeks and months of puppyhood are also key for socialization, and many owners don't expose their puppies to other dogs.

“It’s a disaster waiting to happen for the littermates because they don’t get socialized to other dogs or people, let alone to their owners,” behaviorist and veterinarian Dr. Ian Dunbar tells The Bark. Often owners think that it's enough that the dogs are interacting with each other, “but when the puppies are five or six months old and meet an unfamiliar dog in a novel setting, they absolutely freak out.”

How it can work

two dogs tangled up in leashes It's important to give two bonded littermates lots of alone time, like separate walks. (Photo: tvist/Shutterstock)

If you already have littermates or plan on getting them, retired dog trainer Leah Spitzer of Canine Learning Center, says it's key to "do everything in your power to create two individual dogs." That means giving them lots of time apart from their canine buddy and lots of time with you. She suggests keeping them in separate crates, preferably not near each other, and feeding, walking, playing with and training them separately.

"You have to singularly have a relationship with each dog," says Aga. "You have to spend time with them individually and make sure they bond with you."

She suggests having a friend or family member take one each of the dogs occasionally for the night so they can learn to be apart from each other and take them separately to the vet and to the park. Have training sessions at different times so they're not distracted with each other and are only focused on you, she says.

Basically, you have to do everything twice, but apart.

"Everything you would do with one puppy you need to do with each puppy separately," dog trainer and behaviorist Pat Miller writes in Whole Dog Journal. "This is to be sure they’re both getting the attention, training, and socialization experiences they need, without the interference of the other pup, and so they’re not dependent on the presence of other pup."

A better plan?

puppy at a shelter We know; it's hard to see all the puppies at the animal shelter and only take one home. (Photo: Okssi/Shutterstock)

Littermate syndrome isn't limited to puppies from the same litter, says Aga. Getting two puppies at the same time that are about the same age will also usually result in serious bonding.

But what happens when you go to the shelter and see those two sweet faces and can't bear the thought of splitting up the siblings?

"Fight the urge and wait and get that one puppy home first," Aga advises. Often people realize how much work a puppy is and that changes their mind. But if it doesn't, just wait a few weeks before you bring home another.

"If you want two dogs, stagger them so you can bond with both of them," she says. "Let one have a relationship with your family first."

Mary Jo DiLonardo writes about everything from health to parenting — and anything that helps explain why her dog does what he does.