Monday, November 06, 2006

Can puppies be identical twins?

Who's asking: Hayley Ehrenfeld, Cambridge, MA

Dogs are born in litters of anywhere from one to 15 puppies. The average size is between three and six puppies. These puppies are usually not identical to each other; each puppy starts as a separate egg and develops with its own placenta. In fact, puppies within a litter can even have different fathers (something I learned only recently), so they can look very different from each other.

For many years, people assumed that puppies were always fraternal twins. Fraternal twins (like my sister Kathy and me) are no more like each other than any other siblings.

In fact, puppies can be identical twins, but it's rare. Identical twins come from a single egg (monozygotic), and have the same DNA. Various environmental factors can make them look slightly different from each other, just as with humans. My younger sisters, for example, are identical twins, but even when they were younger, no one who was paying attention had trouble telling them apart.

11 comments:

Tom Ehrenfeld said...

Cool! I thank you, and Hayley thanks you.

Anonymous said...

You know I love the animal facts. Our mutt- oops! 'mixed breed' dog, Ella (before kids and rainshowers of table food), was often mistaken for being part italian greyhound because she had such a slim belly and relatively long legs. The rescue foster mom said that Ella's brother looked like a basset hound with really short legs and fat belly. I figure they had different dads but probably all in the hound dog group.The foster mom also said Ella was a lot smarter than her brother which put him in the dim bulb group as well. Hope he was REALLY cute. I always think about Ella's brother and wish I could have met him.

Anonymous said...

Wow, two sets of twins in your family!

randomtrickpony said...

Ya, I had a dog whose mother was definitely the border collie they said she was, but whose father was not the rough coated merle collie that they claimed (her father was actually a wolf, btw) Moral of the story was, all the other puppies clearly had a collie father (they looked completely different from her!). Funny how that turned out.

Thank you, I'd always wondered about this! Having raised many different sorts of animals, I always wondered about this, since humans could have indenticals. Nobody I talked to knew the answer, and so it's cool to finally have it answered.

Anonymous said...

I just wanted to say thatnks for posting this info. My dog had puppies a little over a week ago, she had 11 total(which surprised us because it's her first litter)! But in that 11 there was a set of identical twins, they cam out in the same sac and everything. Everybody kept telling me I must be mistaken but I saw them be born, I even have it on video. I've been looking for an answer the past two days and I couldn't find one until I found your site! So thanks again!

AnswerGirl said...

Glad it was helpful -- hope all your puppies find loving homes!

Erich said...

I happen to have to chihuahuas that are identical twins, but i was curious if anyone knew what the odds for this were, I know its rare but how rare is it exactly?

Erich said...

oops two*

Anonymous said...

When I was younger my friend had two puppies. She was only supposed to get one but when she did the puppy went into a deppressed like state and whined every night. So she got her sister. Sice then they were fine! They looked identical too!! We could't tell the difference between them so we came to the conclusion that they were twins.

Shannon said...

I have never seen twin puppies until this morning when my Trixie delivered two from the same sac. i knew it couldn't be very common because over the last 4 years I have seen at least 10 litters born between 4 dogs. Thank you for knowledge!

Bobbie Dodson said...

I too just had a litter of Chihuahua puppies... Its her first & was shocked that my 5lb girl had 5 pups. In regards to identical twins, have you ever seen a male & female with the same markings? They are by no means identical, the girl is a caramel color & the male is black. But, they both hv almost the exact same white patches!