In 2021, veterinarians in southern Brazil realized that quite an unusual case had fallen in their laps. An animal they assumed was an adorable dog was brought into their animal rehabilitation center after being hit by a car. However, the longer the animal was in their care, the more confounding its behavior seemed.
"She had eyes resembling a domestic dog and long ears resembling a pampas fox, although she had a dark coat and barked like a dog," said Rafael Kretschmer, a genetics professor for the Federal University of Pelotas, to McClatchy News. "She did not accept food that was commonly offered to dogs, so [we] offered to her small rats, and she accepted."
At that point, the doctors believed they may have a hybrid of sorts on their hands. Reaching out to geneticists for help, the pet hospital received the confirmation it needed: The geneticists verified that the animal is the world's first fox-dog hybrid.
How Dogxim Broke the Internet
The female was named "Dogxim" a portmanteau of "dog" and a "gaxaim do campo," or the Portuguese name for Pampas fox. To verify that she was, in fact, a hybrid, scientists took a look at her chromosomes. Dogxim has 76 chromosomes. Dogs normally have 78 chromosomes, while foxes have 74. Kretchmer said her 76 is "the first evidence of the hybridization."
After her chromosome check, they looked at Dogxim's mitochondrial DNA, otherwise known as the chromosomes she received from her mother. The DNA was from a Pampas fox, and the nuclear DNA had a mix of both dog and fox DNA, presumably from each of the parents.
But how did this hybrid happen in the first place? Researchers Thales Renato Ochotorena de Freitas with Universidade Federal do Rio Grande and Rafael Kretchemer with the Universidade Federal de Pelotas dove into answering this question and what it means for the ecosystem. The pair recently released a study on their findings, Hybridization in Canids.
The study's announcement garnered a lot of eyeballs and commentary on X (formally Twitter), Reddit, and TikTok. A videos of the animal surfaced on TikTok, receiving thousands of views, plus some debate on if she really is the first dog-fox hybrid out there. But, as the study points out, Dogxim is the first documented dog-fox hybrid, which means it is entirely possible that others may exist and just have not been found.
Other scientists weighed in as well. Roland Kays, a biologist from North Carolina State University and the North Carolina Museum of Natural Sciences, shared the study on X, commenting, "What a strange beast!" Kays also pointed out that the dogs and foxes do belong to the same genera, just with "6.7 million years" of separation. Foxes went into the genus Canis, and wolves and dogs went to Canidae.
"Generally, in mammals, species breed with their own kind," Kays told National Geographic. "Sometimes, if they haven't been separated by that long of an evolutionary time period, you can get different species breeding. We see this happen with coyotes and wolves occasionally, but this tends to occur when one of the animals is very common in a region and the other is very rare."
What Happened to Dogxim?
Dogxim was healing from her injuries while the study was being conducted and was promptly relocated to a preserve when she was well enough to do so. Sadly, she died in November 2021, unbeknownst to researchers. The geneticists only learned of her death when they reached out to the state-run facility for a photo prior to publishing the study.
Dogxim's death is under investigation by Brazil's government, but it raised quite a few eyebrows on TikTok, particularly because the facility had very little information on the dog's death, and no autopsy was performed.
Could a Dog-Fox Hybrid Happen Again?
Due to the large population of foxes in Brazil and habitat loss, there could be more opportunities for cross-populations of dogs and foxes to grow.
"The practice of abandoning dogs is a crime in Brazil, but still happens frequently," said Bruna Szynwelski, the studies co-author. "Pets and hunting dogs are often abandoned in natural areas by their owners, contributing to greater occurrence of dogs in natural habitats, including protected areas."
That said, as one hasn't been found since, scientists aren't anticipating another Dogxim. But it's something they'll continue to study, particularly as mixing genetics within species could have devastating effects and introduce diseases and health issues.
"Hybridization between species with different evolutionary trajectories can be a powerful threat to wildlife conservation," wrote the study's scientists.
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