Shelter Rescues Injured Animal—Turns Out To Be World’s First Dog-Fox Hybrid

Article written by Alice Gibbs
Originally published by News Week (Fri, Sep 15, 2023)

Wildlife enthusiasts and scientists alike have been astonished at the discovery of the world’s first dog-fox hybrid in Brazil.

The jaw-dropping discovery began in 2021 when an animal rescue team was dispatched to reports of an injured animal in Vacaria, Rio Grande do Sul.

A hit-and-run incident had left the creature severely injured and the Environmental Patrol transferred it to the veterinary hospital of the Federal University of Rio Grande do Sul (UFRGS). From the hospital, the animal went to the Center for Conservation and Rehabilitation of Wild Animals.

“For us biologists and veterinarians, it is normal to look at all animals differently. We’re trained to look for what’s common and what’s different when we look at an animal. And that’s what happened,” researcher Cristina Araujo Matzenbacher told Newsweek. “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.”

When the animal didn’t accept food usually offered to dogs, she was given small rats which she accepted.

Another behavior of the pampas fox was observed when she climbed the bush that was in the environment where she was kept,” said Matzenbacher.

This was when the veterinarian caring for the animal, Flavia Ferrari, contacted the professor of the genetics department at the Federal University of Pelotas (UFPEL) Thales Renato Ochotorena de Freitas. It was then that the dogxim was transferred to the academics.

How Was the Dog-Fox Hybrid Discovered?

A paper published in August 2023 revealed the discovery of the dog-fox hybrid. First the team employed cytogenetics and genetics techniques to delve deeper into the case of the unusual animal.

This helped them determine the number of chromosomes in the animal’s cells, which turned out to be 76, revealing a significant clue in the investigation.

“In Rio Grande do Sul, only the Chrysocyon brachyurus has 76 chromosomes, however, this species is very different in the phenotype when compared with the dogxim,” Rafael Kretschmer told Newsweek.

Pampas foxes typically have 74 chromosomes, while domestic dogs have 78. During reproduction, offspring inherit half of their chromosomes from each parent. For dogs, this means they contribute 39 chromosomes to their offspring, whereas pampas foxes contribute 37.

The combination of gametes from a dog and a pampas fox results in a total of 76 chromosomes—matching the chromosome count found in the dogxim.

To further bolster their findings, the scientists turned their attention to mitochondrial DNA, a type of genetic material inherited exclusively from the mother. This analysis conclusively revealed that the dogxim’s mother was a pampas fox. In the nuclear DNA, they discovered a mix of genetic material from both domestic dogs and pampas foxes, providing further confirmation of the presence of hybridization in this extraordinary creature.

What Are the Origins of the Dogxim?

The extraordinary discovery of the first every dog-fox hybrid has also prompted theories about other hybrids.

“So far, we have no scientific evidence that there are other hybrids in this region. However, we suspect that this case we have described is not the only one,” researcher Bruna Szynwelski told Newsweek. “Once biologist Herbert Hasse Junior observed two animals with an unusual phenotype in nature in 2019, it is likely that one of these animals was the female hybrid that was run over in 2021, and the other animal was never seen again.”

The circumstances that paved the way for the existence of the hybrid are currently mostly based on theories, but there is a belief it could be linked to the evolutionary narrative of the two species.

“Although pampas fox and the domestic dog diverged about 6.7 million years ago and belong to different genera, we believe little changes have occurred in their DNA, which have led to the existence of this hybrid,” Kretschmer said.

Meanwhile alterations of landscapes within the pampas fox habitat and the presence of domestic dogs in protected areas could also have contributed to the likelihood of encounters between the two animals.

What Does the Dogxim Mean for Wildlife?

From a wildlife conservation perspective, the revelation of the dogxim raises concerns, though.

Matzenbacher explained: “Hybridization, as occurred between a domestic dog and a pampas fox, would have more harmful effects on populations of pampas fox due to the potential for introgression and transmission of diseases from the domestic dog.” Disease transmission and the hybrid’s distinct appearance pose challenges for adaptation and survival in the natural habitat.

The dogxim in question fully recovered from the hit-and-run incident, but after being transferred to the care of another facility, the dogxim died around six months ago.

“So far, we do not know the cause of death of the dogxim. We would very much like to know what happened,” Matzenbacher said.