I just got a call that I love to receive! Someone calling to ask a professional dog trainer their opinion on adopting littermates BEFORE they bring home two puppies from the same litter. My advice? Don't do it!
When I first started training dogs full time, another dog trainer warned me about problems between littermates that grow up together. She said that she never recommends it because it can lead to problem behaviors down the road, including aggression between the dogs. I thought she must be overreacting a bit or exaggerating how bad the problem could be, but I went and researched it a bit anyway. I actually found a number of dog breeders that will not sell two littermates to the same family. I was a little more convinced, but still wasn't sure I would advise people against adopting two siblings from the same litter.
Then, I saw it myself. I had a client that had a male and female that were from the same litter. It was one of the saddest things to watch them grow up together. The male was so completely dependent on the female. He never quite blossomed himself and he also suffocated her much of the time. I don't know if they experienced aggression issues down the road because they've since moved away, but what I saw was enough to make me think that it was not a good idea. I've also seen parent/child pairings that resulted in aggression problems when the puppy matured into an adult dog.
Here is a little of what I have since discovered on the issue of littermates growing up together:
1 - It doesn't have to be littermates. The same problems may occur when you raise either a mother and child or father and child pair. It also appears that it may be problematic when you raise two unrelated puppies of the same age together. In general, we recommend waiting a minimum of 6 months to a year AND getting your first dog's manners under control before you bring another dog home.
2 - Raising two littermates can lead to, for lack of a technical term, "failure to blossom" in one of the dogs. In fact, according to Steven Lindsay (author of Handbook of Applied Dog Behavior and Training), one Guide Dog organization reported problems when a mother and child pair was fostered together and when littermates are fostered together. Quoting a representative of the organization: "I cannot remember a single dog who was raised with her mother to adulthood who could be successfully trained for a Guide Dog. Where two litter mates are raised together in the same home we have had the same results. . . . one becomes a successful candidate for Guide Dog work and one fails, even if their aptitude tests were equal." (Lindsay, 2000, p. 50).
3 - Two puppies raised together don't often have a chance to bond to family members because they're so busy bonding with one another. This can lead to trouble with training and behavior, and over-bonding with one another may lead to difficulties with being left alone or separated for even short periods as adults.
4 - Many trainers recommend the following steps if you have littermates:
- Take time with each dog individually EVERY day for the first 6 or so months you have them so that they can bond with you instead of just bonding to one another. Go out for separate walks (you'll need to do this to teach nice leash manners anyway), have some one-on-one training sessions with each of them, and attend a group puppy class with each one (separate classes!).
- Separate the dogs when you are gone during the day (for the first 6 months). You can do this by crating them in different rooms of the house or by babygating them into separate rooms (in a way that doesn't allow them to interact through the gate). I know, you're thinking this is foolish because I want my dogs to play with each other and keep each other company during the day. They will do that. Someday. Just not during their formative months. Let them each develop an individual personality first and then allow them to be together during the day.
Now that I've said all that, I want to be frank. NONE of what I've just said has been proven in a verifiable, repeatable study. I have yet to see a study that confirms the claims I've just made (I hope that someday we'll have more information on this, but as of yet, I don't think any studies exist). For those of you that know me or read my blog regularly, you'll know that I don't like to pass on information that is simply based on anecdote. There is far too much mythology and plain-old-junk out there in dog training to justify throwing ideas out willy nilly. However, I've seen enough evidence of problems with raising two littermates or a parent/child pair that I'm willing to warn dog owners of the problems and recommend that they not adopt a pairing like this. At the very least, I make recommendations about precautions they can take, always with the caveat that the problem hasn't been studied enough to be verifiable.
I just attended the annual conference of the International Association of Animal Behavior Consultants and I asked a Veterinary Behaviorist that was at the conference what she thought of the problems of raising littermates together. She confirmed my suspicion that there haven't been any studies on the topic, but, she has also seen enough problems to cause her to recommend that clients not adopt a littermate or parent/puppy pair. So, take it for what it is worth - just anecdotal evidence - but I for one won't adopt any littermates any time soon!