Your Dog Can Catch Distemper Without Touching Another Dog: What a Study in Colombia Shows
3 min read
It's easy to think distemper only spreads from dog to dog: at the park, at the vet, on the street. A 2025 study published in Viruses, carried out by researchers at Colombian universities in the Aburrá Valley (the region where Medellín is located), shows that the chain of transmission is wider than it seems.
The finding
The researchers collected samples from 34 domestic dogs with distemper symptoms at five veterinary hospitals, and from 13 crab-eating foxes (Cerdocyon thous, a wild species common in urban and peri-urban areas of the region) that were rescued with severe neurological signs. When they sequenced the virus's genetic material in both groups, they found something notable: dogs and foxes from the same area were infected with the same lineage of the virus, known as South America/North America-4.
The most revealing part is that none of the infected dogs had reported contact with the foxes or with wildlife. In other words, the virus is circulating in both populations (domestic and wild) at the same time, probably through indirect chains of transmission: one dog infects another dog, that dog has contact with an urban fox, and the fox can in turn expose other dogs in a different part of the city.
Why this matters for your dog
The study found that the virus's genetic analysis showed at least four separate introductions of this variant into the area, which suggests this is not an isolated outbreak but a sustained cycle of transmission between domestic animals and wildlife. This has a direct practical consequence: a dog that never leaves its neighborhood, doesn't visit parks, and has no contact with sick dogs can still be exposed, because the virus does not depend exclusively on the dog population to stay active in the environment.
They also found something concerning about vaccination: of the 34 dogs with confirmed distemper, only 52.9% had received at least one dose of the vaccine, and 68% were younger than 12 months. This confirms what we already know: puppies without a complete vaccination schedule remain the highest-risk group, regardless of whether or not they have direct contact with wildlife.
The researchers' own conclusion
The study closes with a call for an integrated approach: vaccinating dogs is not enough, there also needs to be surveillance and management of the disease in the wild populations that share the same urban and peri-urban space. For a dog owner, the implication is simpler: completing the vaccination schedule on time remains the best defense, precisely because the virus can arrive by routes you can't control or see.
Source: Rios-Usuga C, Ortiz-Pineda MC, Aguirre-Catolico SD, Quiroz VH, Ruiz-Saenz J. "Concurrent Circulation of Canine Distemper Virus (South America-4 Lineage) at the Wild-Domestic Canid Interface in Aburrá Valley, Colombia." Viruses. 2025;17(5):649. DOI: 10.3390/v17050649. Published under a CC BY 4.0 license.