We are thinking about getting a puppy who was the only one in the litter. She has a slight deformity to her breast bone. The vet says its fine. Do singleton pups have more health issues than larger litters?
This is a very important topic. Singleton pups can have many more behavioral issues than pups from regular litters. Unless the breeder is very experienced and gave a lot of very specific socialization and training to this pup from day 1, you could be in for some difficulties. We had a singleton pup born into Shih Tzu rescue (a pregnant female was surrendered) and he turned out well, but it was very hard work for his foster mom. I hope you will do as much research as possible on Singletons before you take this on.
We have a chi mix pup who was a singleton. He is now 16 months old and has been here all of his life. He fits in well with the gang but did have some difficulties learning his place in the pecking order of the pack. He really wanted to challenge the older male chis even after he was neutered which led to some fairly "tense" moments which I allowed to play out. He had to learn and accept his place and the quickest way to that end was to let him be "taken down" by some of the others a few times. He is stubborn. so it took a while, but eventually worked. He had no physical problems~~ was quite chubby as a baby, due to no competition at the "buffet bar!" Now he is fit and trim and quite a character.
I don't believe they are more susceptible to illnesses, not by default anyway. If you had a pup that ended up being that way, I don't think it would point back to being a singleton. That being said, I don't know 100%, that would just be my gut instinct, because the puppy doesn't have to share any of the "goods" during its critical growth period....so to me it'd seem like it'd be healthier