‘Littermate Syndrome’ Myths Busted–You Don’t Need to Adopt Out Pets in Pairs

It’s been said for years that kittens MUST be adopted in pairs, and that puppies MUST NOT. 

This is wrong.

There is no behavioral science behind these exceedingly common myths that kittens who aren’t adopted in pairs, or puppies who are, will turn into gremlins who destroy your home at midnight. Or won’t be well behaved. Or will have bad social skills. 

It’s time to put these myths—called “single kitten syndrome” when applied to cats, and “littermate syndrome” for dogs—to bed, along with any adoption policies that are driven by them. 

With our growing understanding of animal behavior and development, there has never been a single published research study proving the existence of single kitten syndrome or littermate syndrome. 

Not a single one.

But despite animal behaviorists’ best attempts, the myths persist. And this has real consequences. Adopters may be discouraged or even prohibited from adopting a single kitten, or multiple puppies. 

Meanwhile, as we write this in the middle of summer, shelters are full.

We know that shelter overcrowding is catastrophic. Why would we put up needless barriers to placing these very same animals into loving homes

For many situations we face in animal sheltering, there are no perfect answers, no black and white. In this case, we do have an answer: We know kittens and puppies are better served in homes than in shelters. 

Single kitten syndrome and littermate syndrome are not based in science. These myths should not stand in the way of adoptions—especially while 1.5 million animals are euthanized in U.S. animal shelters every year.


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