These days, it’s really easy to identify new viruses. Our technology has advanced so much that you can sequence a vast array of viruses from almost any sample from an animal, person or the environment. Finding the viruses is easy, but understanding what, if any, roll they play in the grand scheme of things is a much greater challenge.

As a reviewer for scientific journals, I see lots of papers describing new viruses. Most of these are probably old viruses that we just recently identified. Often, studies say “look what we found” but don’t take the next step to figure out if the “what” is relevant, or they tend to overstate the potential relevance. I might find a new virus in a sick animal, but that doesn’t mean the virus is causing disease; it might just be part of the normal innocuous viral population that lives on and around even healthy animals.

We don’t want to dismiss new findings, but we also don’t want to over-react. Take amdoparvovirus for example, or more specifically, raccoon dog and fox amdoparvovirus (RFAV). Amdoparvovirus in part of the Parvoviridae family, along with the more well-known canine parvovirus, but is a distinct genus that includes a variety of different viruses that infect a range of mammals, particularly mustelids (e.g. ferrets, mink), skunks and raccoons. One of the most well-recognized members of this genus is the cause of Aleutian disease, a serious disease in mink.

Raccoon dog and fox amdoparvovirus was first reported in 2014 as part of an investigation of an outbreak in raccoon dogs and Arctic foxes on fur farms in China. Disease was most severe in young animals, with signs of decreased appetite, weight loss, slow growth and chronic diarrhea, with histological evidence of gastrointestinal and kidney damage.

A recent preprint (i.e. a non-peer reviewed preliminary paper) (Gajdov et al. 2026) describes an outbreak of disease in dogs attributed to RFAV. Not surprisingly, given the world we now live in, social media in some places has taken it from “here’s a potential spillover of a virus in a single kennel” to “OH NO! A NEW DOG VIRUS!!!” This preprint describes an interesting outbreak with some nice details along with some clear gaps.

• I try to pay attention to reports of “new” issues, but always with a healthy dose of skepticism. Most of the time, a strange disease is just an unusual presentation of a normal disease. Similarly, a “new” disease event (like RFAV in dogs) is more often a rare event or something that’s happened before but not previously been recognized, versus true emergence of a new problem.

Here’s a synopsis of the outbreak and pathogen investigation described in the preprint:

• An outbreak of disease was identified in Dobermanns in a kennel in Serbia. Affected dogs had abnormalities such as ocular and nasal discharge, conjunctivitis and weight loss, with some dogs also having “blue eye,” liver disease or, at later stages, neurological disease (which sounds pretty textbook for canine distemper). They tested for distemper, among other things, and results were negative. Samples were submitted initially from a dog and her two puppies, but it’s not clear if only those dogs were tested for distemper or whether other dogs were as well. More details about the testing (e.g. test type, numbers, timing) would be useful to help understand if we can really exclude distemper as the cause. As the old adage goes, common things occur commonly.   However, they mention repeated testing, and presumably they did a pretty good investigation before embarking on sequencing to identify any new pathogens.
• The authors then went virus hunting, using sequencing to look for viruses present in lung, kidney and liver samples from the dog and puppies. They found “RFAV” — more specifically, they found sequences with 97% genetic similarity to the limited number of known RFAV genomes. We know relatively little about the genetic variation of this virus in nature, which is important for interpreting this finding. If the virus is genetically similar to RFAV strains circulating in wildlife, that would support direct spillover into the kennel from an infected wild animal. If it is substantially different from viruses circulating in wildlife, that suggests that it could be a distinct variant, although that still wouldn’t mean it is a dog-adapted virus. It’s way too early to say. At this point, a spillover of RFAV into dogs seems more likely than the emergence of a distinct canine virus.
• They then developed a PCR test specifically for this virus. They got positive results from one other epidemiologically-linked dog, and an undefined number of healthy dogs from other locations tested negative. They don’t say if they tested other affected dogs, which is important context. The more sick dogs that test positive and the more healthy dogs that test negative, the more convincing it is that the virus is clinically relevant. But even with these kinds of findings, association doesn’t necessarily mean causation.

Lack of histopathological investigation (both in general and specific testing to look for evidence of canine distemper virus) is a limitation of this paper. I wonder if they’ll get asked to do that prior to peer-reviewed publication, if they still have tissues from these animals.

Another gap is this paper is the limited epidemiological data. No information was provided about potential sources of exposure or transmission patterns. I wanted more details about the kennel, numbers of affected and unaffected dogs, a timeline of how infections developed, kennel management practices and diet, as well as potential opportunities for direct or indirect contact with wildlife. There shouldn’t be farmed raccoon dogs or foxes in the area since that’s been banned in Serbia, but wild fox exposure would be worth investigating.

In the end, we’re left asking if this situation is:

1. A new emerging disease caused by a new virus that may lead to widespread problems in dogs..
2. An uncommon spillover event that happens periodically but just hasn’t been identified before, because such detailed investigation of kennel outbreaks is rare.
3. An outbreak cause by a co-infection where RFAV was perhaps a contributing factor in disease but there was something else involved too
4.  A confluence of factors that allowed a really rare scenario to develop.
5. A distemper outbreak that was not detected.

I’d like to have convincing details to rule out E before anything else, but by next guess would be B… that this virus is “new to us” versus “truly new”.  

I don’t want to downplay the usefulness of information though. Studies like this form the foundation for further studies to help us figure out if this virus is actually a health threat in dogs and how common it is in the population (sick or healthy). Now that this is on the radar, testing can be done (through research labs) in situations where it might be relevant. We’d also need to have some testing of healthy dogs to provide context.

Raising awareness versus causing panic is always a tough balance with infectious diseases. This report tells us we have something else to consider and to investigate further, not that we have a new concerning problem that’s causing an imminent threat.