Animals get distemper primarily by breathing in virus particles released by infected animals. The virus travels in tiny airborne droplets from coughs and sneezes, making close contact with a sick animal the most common route of infection. But distemper can also spread through direct contact with saliva, urine, feces, and other bodily fluids, and the story differs depending on whether you’re talking about dogs or cats.
Airborne Spread Is the Primary Route
Canine distemper virus enters the body through the upper respiratory tract. When an infected animal coughs, sneezes, or even breathes heavily, it releases microscopic droplets loaded with virus. A healthy dog nearby inhales those droplets, and the virus lands in the airways, where it quickly moves to the tonsils and lymph nodes. From there, it replicates and enters the bloodstream, spreading to cells throughout the body, including the intestinal and respiratory tracts.
This aerosol route is why distemper moves so efficiently through shelters, kennels, and other places where animals are housed closely together. A single infected dog shedding virus in a shared space can expose every unvaccinated animal in the building. Some infected dogs continue shedding virus particles for several months, meaning they can spread the disease long after their symptoms appear to improve.
Other Ways the Virus Spreads
Beyond airborne droplets, animals can pick up canine distemper through direct contact with infected saliva, urine, or feces. Shared water bowls, food dishes, and bedding can all become contaminated. Occasionally, a dog becomes infected by ingesting material that contains the virus rather than inhaling it.
Contact with contaminated objects (like toys or kennel surfaces) is a possible but less common route. The virus doesn’t survive long outside a host. At room temperature, it persists on surfaces for only several hours. In colder weather, though, it can remain infectious for weeks, which helps explain why outbreaks sometimes spike in winter months.
Pregnant dogs can also pass the virus directly to their unborn puppies. Research published in the American Journal of Veterinary Research confirmed that transplacental transmission occurs in dogs. In documented cases, mothers with even subclinical infections (showing no obvious symptoms) delivered puppies already infected with the virus. These congenitally infected pups are especially vulnerable because their immune systems are not yet developed.
Wildlife Is a Major Source
Canine distemper doesn’t just circulate among pet dogs. It infects a wide range of wild carnivores, including raccoons, skunks, foxes, and wolves. Ferrets are also highly susceptible. When distemper outbreaks sweep through local wildlife populations, the risk for pet dogs in the area rises significantly.
The exchange goes both ways. Unvaccinated dogs can catch the virus from a raccoon rummaging through the yard, and they can also serve as a source of infection for wildlife. This two-way spillover between domestic and wild animals is one reason distemper is so difficult to eradicate. Even if every pet dog in a neighborhood is vaccinated, the virus continues circulating in raccoon and skunk populations, creating a persistent reservoir of infection.
Feline Distemper Spreads Differently
The disease called “feline distemper” is actually a completely different virus. Canine distemper is caused by a paramyxovirus, while feline distemper (technically called feline panleukopenia) is caused by a parvovirus. A cat cannot catch canine distemper, and a dog cannot catch feline panleukopenia. They share the common name “distemper” for historical reasons, not because they’re related diseases.
Feline distemper spreads through inhalation or ingestion of infected material, similar to the canine version. But there are key differences. The feline virus is shed in all body secretions and excretions, and recovered cats may continue shedding virus for months. Fleas and other insects, particularly flies, can also play a role in transmitting feline distemper, a route that doesn’t apply to the canine version. Once inside the body, the feline virus targets rapidly dividing cells, including those in the intestinal lining and bone marrow, which is why it causes such severe drops in white blood cell counts.
The feline virus is also far hardier in the environment than canine distemper virus. While canine distemper breaks down within hours at room temperature, feline panleukopenia virus can survive on surfaces for months or even longer, making environmental contamination a much bigger concern for cats.
Which Animals Are Most Vulnerable
Puppies are at the highest risk for canine distemper. Young dogs that haven’t completed their full vaccine series have limited immune protection, and their developing immune systems struggle to fight off the virus once it takes hold. Dogs in shelters, rescue situations, or any environment with unknown vaccination histories face elevated risk simply because of exposure to other animals of uncertain health status.
Any unvaccinated adult dog is also vulnerable. The core combination vaccine given to dogs (often called DHPP) includes protection against distemper, and studies show strong immune responses even after the first dose. In one study, all puppies vaccinated at six weeks of age developed protective antibody levels against distemper after their initial injection. A full vaccine series, followed by appropriate boosters, provides reliable long-term protection. Vaccinated dogs that encounter the virus typically fight it off without ever showing symptoms.
For wildlife, the picture is grimmer. There is no practical way to vaccinate wild raccoon or skunk populations, so distemper periodically sweeps through these species in large outbreaks. If you notice raccoons in your area acting disoriented, unusually tame, or visibly sick, keeping your dogs away from them and ensuring vaccinations are current is the most effective precaution.