Dear Doctor: Do Littermates Recognize Each Other After Being Separated?

Q. Can littermates recognize their “siblings” that they haven’t seen in a long time? My dog and his four littermates are all from Tennessee but ended up in New England and were adopted out to different families by the time they were 12 weeks old. Now they are five, and three of us owners got together for a meet-up recently. We thought the dogs would be ecstatic to see each other again, but while they certainly had a good time horsing around together, they did not appear to have an affinity for each other that was any greater than their affinity for other dogs they have come to know and get along with. At the same time, I have read about littermates so thrilled to see each other again after having been separated for a long time that you’d think they were on one of those TV shows where adoptees try to find their birth families. What’s the answer?

Conrad Schultz

Henniker, New Hampshire

Dear Mr. Schultz,

A. A lot of people have wondered about this. The scientific evidence either way is essentially nil, although some researchers believe a dog has to have been with his or her littermates for at least the first 16 weeks of life to be able to recognize them later on.

The anecdotal evidence, on the other hand, is abundant — and also leads to no firm conclusions. Some people have written about dog “siblings” lost to each other for years who were perfectly content to meet up but did not appear to have familial recognition. They were no more jazzed to get to see each other than to see other dogs.

Others have described the sheer delight exhibited by littermates after they hadn’t seen each other for a long period. Just this year, two couples who were not acquainted came across each other at Seattle’s Pikes Place Market and found that their identical-looking dogs were absolutely over the moon about the chance greeting, literally almost hugging each other. It turned out they had both been adopted from Russia 11 months earlier, when they were just weeks old, and tattoos proved they were from the same litter.

People like the idea of dog siblings recognizing and loving each other. The moment of that pair’s reunion happened to be caught on camera by someone watching as the scene unfolded, and the chance meet-up went viral and was seen by literally millions of Facebook viewers.

Did they truly remember each other as littermates, or did they just have a good feeling about each other? Who knows? Dogs of the same breed often gravitate toward each other, so it’s not possible to say. What we know is this: the scent of another dog stays with a dog for a long time. So a littermate not seen, er, sniffed for years may have a comforting, familiar scent to a dog who comes across him or her after a long period of separation. But whether the dog is processing that it’s a familial connection, we’ll probably never know for sure.