'Parasitic twinning' could explain calf born with two extra legs

'Parasitic twinning' could explain calf with legs growing from head In short: Experts say "parasitic twinning" or genetic mutations could explain why a calf grew extra limbs in utero. Veterinarian Megan Smith operated for 90 minutes to remove the extra limbs from the heifer's head. The calf has made a full recovery and has been returned to her mother. "Parasitic twinning" could explain why a southern Queensland calf was born with two extra legs growing from its head. The heifer, nicknamed Spider, made a full recovery after surgery to remove the limbs when she was just over a week old. A geneticist said it was difficult to determine how common birth anomalies were in cattle, in part due to a lack of research data. But for the vet who helped reunite Spider with her mother, there was no doubt it was a once-in-a-career operation. Incomplete separation Imke Tammen from the University of Sydney's School of Veterinary Science has studied the inherited traits of livestock for more than 30 years. Dr Tammen said exactly why Spider was born with extra legs would likely remain a mystery, but abnormalities could happen in the womb. "It could be parasitic twinning, where you basically have an embryo splitting into two but not separating completely,"she said. The rare phenomenon, where an embryo begins developing as twins but stalls, can leave part of the second animal attached to the first. Dr Tammen said there could be other explanations too. "Sometimes … something goes wrong in the development of just one animal and that can result in additional legs," she said. In some cattle, extra limbs can also be linked to inherited genetic conditions. Scientists have identified genetic mutations responsible for some forms of these abnormalities, meaning DNA testing can sometimes help farmers identify animals carrying the problem. However, Dr Tammen said there was not enough information to say how common these conditions were in cattle. She urged farmers who discovered an unusual birth to report it to their veterinarian as collecting information about cases can help researchers understand what causes them. Surgical success For Pittsworth veterinarian Megan Smith, the case was unlike anything she had seen in her 20-year career. "I've never seen legs coming off the head like this,"Dr Smith said. The calf's owners, who wished to remain private, were considering putting her down, but the vet offered to attempt the risky surgery at minimal cost. She and a veterinary nurse anaesthetised the calf, which appeared to have some Angus genetics, and spent more than 90 minutes removing the unusual limbs. Dr Smith said the case was a rare opportunity for her team and a chance to give the calf a normal life. "We're just so fortunate to live in such a great community where we can have that bit of a trusting relationship that people are prepared to even ask the question,"she said. "Sometimes you can have these great opportunities and can achieve great things, so it's awesome." The extra legs could have caused serious problems as the calf grew, including making her head uncomfortable and affecting her balance. Spider recovered quickly. Dr Smith said the calf was drinking from a bottle just an hour after waking from the operation before returning to her mother. "She was back feeding off her mum … kicking about and living her best life,"she said. Dr Tammen praised the regional vets for taking on the surgical challenge. "I think that's excellent," she said. "It's improving the welfare of that calf and is a very appropriate way of ensuring that the calf has a good life."