Genetically edited beagles These were the two 15-month-old beagles whose genes were successfully edited. Hercules is on the left, and Tiangou is on the right. Courtesy Liangxue Lai

Genetically engineered puppies are here — at least, a couple of them. And they're strong.

Researchers at the Guangzhou Institutes of Biomedicine and Health in China have used the latest gene editing technology to edit the genomes of beagles. They described their results, which we first spotted in MIT Technology Review, in a study published in the Journal of Molecular Cell Biology.

By removing copies of a gene called the myostatin gene, the scientists created dogs with a genetic mutation that can cause the dogs to build up twice the muscle mass of normal beagles.

In this case, while two dogs had modified genes, only one has a significant increase in muscle mass compared to its littermates.

This was just the first of a series of experiments in creating genetically altered beagles, Liangxue Lai, one of the researchers involved, told Tech Insider in an email.

"We plan to make dog models for human genetic disease," he wrote.

What this means

The researchers say that this is the first time that gene editing technology has been used to create genetically modified dogs, though other scientists have done similar work in cattle and other animals — they write in the paper that dogs have some unique reproductive characteristics which can complicate this work. Earlier this year, the same myostatin change was made to create extra-muscly pigs.

These new beagles show both the power and the current limitations of genetic editing technology.

Using the tool, CRISPR Cas-9 — which basically functions as a find-and-replace editor for DNA by searching out certain sections and either removing that code or potentially replacing it with something new — researchers were able to mimic a mutation that has been seen before in nature.

As Regalado writes, the mutation the scientists introduced in the beagles sometimes naturally occurs in the whippet dog breed. As you can see in the image below, the dogs on the right lack the same functioning myostatin genes that were disrupted to make the muscular beagles. They are significantly more muscular than their brethren with one copy of the gene in the middle and two copies (as is "normal") on the left.

whippet bully whippet The dog on the top right and middle right was born in the same litter as the dog on the top left, but the lack of myostatin genes gives it double the muscle mass. doi:10.1371/journal.pgen.0030079.g001

Researchers intentionally made this same change at Guangzhou.

But the gene editing process wasn't necessarily smooth or easy, and didn't work perfectly. The researchers first attempted to implant 25 edited embryos out of a group of 30 they'd collected into six dogs, but none resulted in pregnancy. They write in the paper that they think that this was because of a complication in the dog reproductive cycle.

Next they used a different approach to inject 35 edited embryos into 10 dogs, eight of which became pregnant. Those eight dogs gave birth to 27 puppies, but only two showed the genetic modification they'd been aiming for: a male named Hercules and a female named Tiangou.

Tiangou has the increased muscle mass that would be expected for a dog without the myostatin genes. Hercules does not, but there's some evidence that not all his cells stopped producing myostatin, which means that he's what's known in genetics as a chimera, with some edited cells but some not. There was no other "detectable off-target" or unexpected mutations that occurred as a result of the edit, the researchers write.

All this showed that dogs could be genetically edited — something expected but something that hadn't been demonstrated yet.

But the level of accuracy was still far from what you would want if you were to try to knock out a disease-causing gene in a human.

Still, they found that these mutations could be passed on to offspring that these dogs have in the future. If they were to do this with enough dog embryos to create a breeding population, they could create a whole new "breed" of dog — not that different from what humans have done for thousands of years.

What's next

genetically edited cattle The cow on the right has been genetically editing using a different method to have more muscle due to the same tweak to the myostatin gene. Proudfoot et al, Transgenic Res. 2015

Lai told Regalado that they aren't interested in creating pets, like genetic research center BGI is doing with some micropigs that were created using the same technology.

But he did tell him that in theory, someone else could make similar dogs, since they have "more muscles and are expected to have stronger running ability, which is good for hunting, police [and military] applications."

For now, Lai tells us, they plan to make dogs that can model neurodegenerative diseases like Parkinson's in order to better understand and develop treatments for those diseases. He says these dogs, which are frequently used in biomedical research, are the "perfect animal model for behavior study," since they are smarter than other animal models.

Simple genetic edits like a myostatin change are just further proof that the age of genetically engineered animals has arrived. If an effect or trait is caused by a single gene, that can now be turned on or off.

Earlier this year, Dr. Scott Fahrenkrug, the CEO of a Minnesota company that edits animal genomes called Recombinetics, told Tech Insider that this sort of work can create stronger, healthier cattle that are more resistant to disease and to rising temperatures.

The thing stopping us from changing characteristics like intelligence is that such complex characteristics are controlled by many genes (and other factors). We don't know exactly how those genes interact and how we would need to tweak a genetic code to create a super-smart dog or monkey.

Yet all of the efforts to perfect this technology in animals make us more confident and capable of editing the building blocks of life. At some point, that technology will likely be accurate enough to use in humans.