A litter of puppies has been born through IVF for the first time, reports a study that has implications not only for veterinary medicine but also for human genetic research.
Scientists at Cornell University, New York, transferred 19 embryos to a female 'host', leading to seven live births. The researchers say that the breakthrough, after years of failed attempts by scientists to use IVF in dogs, could lead to new ways to preserve endangered dog species, or to treat canine genetic diseases using genome-editing techniques such as CRISPR.
'Since the mid-1970s, people have been trying to do this in a dog and have been unsuccessful,' said Dr Alex Travis, lead researcher on the study. 'With a combination of gene-editing techniques and IVF, we can potentially prevent genetic disease before it starts.'
The research, described in PLoS ONE, also has implications for research into human disease. Over 350 heritable disorders in dogs are comparable with human conditions, almost twice the number of any other species, and successful IVF will make dogs more suitable for certain types of research.
'Because dogs share so many genetic traits and diseases with people … this technique also gives us new opportunities both to study genetic disease, and with gene editing, potentially prevent it from happening. This will have important implications for both veterinary and human medicine,' Dr Travis told The Guardian.
In order to overcome challenges presented by a dog's unique reproductive cycle, which is different to other animals and humans, the researchers needed to adjust IVF techniques. Dog oocytes mature differently once released, so had to be harvested later in the cycle than other animals; they are also difficult to examine using usual microscopy techniques because they contain fatty material that looks dark.
Dog sperm requires different conditions to fertilise eggs, needing additional magnesium, and female dogs are only fertile once or twice a year, which means that dog embryos must be frozen and implanted at the correct time in the cycle.
Professor David Argyle, Head of the School of Veterinary Medicine at the University of Edinburgh, who was not involved in the study, agreed that the new techniques would help in our understanding of inherited diseases in both dogs and people.
'Importantly, it is becoming apparent that dogs and humans share many common biology, diseases and syndromes, and it is likely that these new techniques could have significant benefit for the study of human diseases as well as canine diseases,' Professor Argyle said.
Aimée Llewellyn, Head of Health and Research at The Kennel Club, acknowledged the significance of the research, but voiced concerns to The Telegraph about potential ethical issues of IVF in domestic dogs. 'A pet dog cannot consent to invasive treatments such as IVF as a human can,' she said.
She added that 'the Kennel Club supports research that directly benefits the domestic dog whilst ensuring the health and welfare of the animal remains top priority, which may not be the case when invasive procedures are involved'.