Not news: Irish wolfhound mother gives birth to seven puppies.
[S]omething was different about this delivery. When he started the procedure, [Dr. Kurt] de Cramer noticed that the wolfhound had an unusual bulging by her uterus.
At first, he thought the lump was excess fluid surrounding a foetus. De Cramer painstakingly extracted this foetus from the bulge by making an incision into the dog’s uterus.
That was when the real shock came. He found not one, but two foetuses. They were both attached with umbilical cords to the same placenta.
Five siblings followed in single file, connected to five separate placentas.
It is thought that identical twins are rare because, when two foetuses share one placenta, they do not get enough nutrients from the mother and are therefore less likely to survive.
For instance, identical twin foetuses have been reported in horses, but none have survived. A horse’s placenta is not efficient enough to transport oxygen for two foetuses.
Citation: DOI: 10.1111/rda.12746.