What Is Distemper in Raccoons: Symptoms & Risks

Distemper in raccoons is a viral disease caused by canine distemper virus (CDV), a highly contagious pathogen that attacks the respiratory, gastrointestinal, and nervous systems, and it is the most common infectious cause of death in raccoons across much of North America.¹ The disease progresses in stages, starting with flu-like signs and often ending in severe neurological dysfunction that many people mistake for rabies. Understanding how distemper works, what it looks like, and who it threatens is useful whether you share your yard with raccoons, own a dog, or have stumbled across a raccoon behaving strangely and want to know what you are looking at.

The Virus Behind Distemper

CDV is a morbillivirus, which places it in the same family as measles in humans and rinderpest in cattle. It is an enveloped RNA virus, meaning it is relatively fragile outside a host and does not survive long on surfaces exposed to sunlight, heat, or common disinfectants. Despite that fragility, CDV is extremely efficient at spreading between animals in close contact. The virus is described as “pantropic,” meaning it can infect many different tissue types throughout the body rather than being limited to, say, the lungs or the gut.² That broad tissue appetite is a big part of why distemper causes such varied and severe symptoms.

Research on experimentally infected raccoons has shown that the virus first targets immune cells, particularly lymphocytes, and to a lesser extent certain other white blood cells. By about three weeks after infection, the virus has spread to epithelial tissues, meaning the linings of the respiratory tract, gut, skin, and other surfaces.³ This two-phase pattern explains a lot about the disease’s timeline and why an infected raccoon’s condition deteriorates the way it does.

How Raccoons Catch It

CDV spreads primarily through direct contact with an infected animal’s respiratory secretions, urine, or feces. A raccoon sniffing another raccoon’s waste at a latrine site, sharing a den, or getting into a face-to-face squabble is enough to pass the virus. Because raccoons are social animals that often share feeding areas, communal dens during cold weather, and latrine sites, a single infected individual can expose many others quickly. CDV can also be transmitted through airborne droplets over short distances, similar to how a cold spreads through a crowded room.

There is evidence that the virus may also persist in skin tissue, even when the skin looks completely normal under a microscope. Researchers examining skin samples from 36 raccoons found CDV in both the outer skin layer and the lining of blood vessels within the skin, regardless of whether the animal showed visible skin lesions.² Whether skin-to-skin or skin-to-environment contact plays a meaningful role in transmission is still unknown, but the finding suggests the virus has more routes of exit from an infected animal than just the obvious ones like coughing and urinating.

Symptoms Stage by Stage

Distemper in raccoons tends to unfold in a recognizable sequence, though the timing varies. The stages overlap, and not every raccoon will display every symptom, but the general arc is consistent enough that wildlife professionals can often identify the disease on sight.

Early Respiratory and Gastrointestinal Signs

In the first week or two, the virus hammers the immune system and begins attacking mucosal surfaces. You might notice a raccoon with a runny nose, watery or crusty eyes, sneezing, or coughing. Some animals develop diarrhea or vomiting. Fever is present but obviously hard to observe in a wild animal. At this stage, a distempered raccoon can look like it simply has a bad cold. It might still be eating and moving around, though it will often appear lethargic and less wary of humans than a healthy raccoon would be.

Laboratory studies of raccoons inoculated with CDV confirm that viremia (virus circulating in the blood), lymphopenia (a sharp drop in immune cells), and fever all develop within the first few weeks of infection.³ The immune suppression is critical: it leaves the raccoon vulnerable to secondary bacterial infections that pile on top of the viral damage, often turning a pneumonia-like cough into something far more dangerous.

Neurological Signs

The phase that most alarms people who encounter a distempered raccoon is the neurological stage. Once CDV reaches the brain and spinal cord, the animal’s behavior changes dramatically. Common neurological signs include:

Circling: walking in tight, repetitive circles, sometimes for hours.
Head tilt: a persistent lean to one side.
Seizures: ranging from subtle twitching of the face or limbs to full-body convulsions.
Disorientation: wandering aimlessly, bumping into objects, or approaching humans without fear.
Jaw chomping: rhythmic chewing motions with nothing in the mouth, sometimes accompanied by drooling.
Paralysis: weakness or complete loss of function in the hind legs, sometimes spreading to all four limbs.

A raccoon displaying these signs is not aggressive in the way a rabid animal might be, but it can appear aggressive simply because it has lost its normal wariness and coordination. It may stumble toward you not out of hostility but because it has no idea where it is going.

Hardpad and Skin Changes

In some cases, the foot pads and nose become thickened and cracked, a condition sometimes called “hardpad.” This happens because the virus damages the keratin-producing cells in those areas. It is not always visible in raccoons (it is more commonly noted in dogs), but when present, it is a distinctive clue. The skin involvement fits with the finding that CDV infects epithelial tissue broadly, including in areas that look outwardly normal.²

How Distemper Differs from Rabies

People who see a raccoon stumbling around in the daytime with drool on its chin almost always think of rabies first, and for good reason: both diseases cause bizarre neurological behavior. But the two are caused by completely different viruses, progress differently, and carry different risks to humans.

Rabies tends to produce either extreme aggression (“furious” rabies) or near-total paralysis (“dumb” rabies) and kills the animal within days of symptom onset. Distemper, by contrast, unfolds over weeks and produces a wider range of neurological signs, including the characteristic circling and jaw-chomping that are uncommon in rabies. A distempered raccoon often looks confused and sick rather than actively hostile. That said, the overlap is real enough that you should never try to diagnose the difference yourself. Only laboratory testing can confirm which virus is involved, and any raccoon showing neurological symptoms should be treated as potentially rabid until proven otherwise.

The critical practical difference: rabies is transmissible to humans through bites or scratches, while CDV is not considered a human health threat. There has never been a confirmed case of CDV causing illness in a person. So while both diseases mean you should keep your distance and contact animal control, the risk to you personally is very different.

Risks to Dogs and Other Animals

CDV does not limit itself to raccoons. The virus infects a wide range of carnivores and omnivores, and raccoons serve as a major reservoir for the virus in many regions. Surveillance across Michigan from 2008 to 2018 documented CDV spreading through raccoons, striped skunks, and gray foxes, while also spilling into additional wildlife species.⁴ In New England, a distinct genetic clade of CDV was confirmed in fishers, gray foxes, mink, skunks, and raccoons within a single 12-month period.⁵

For dog owners, this is the most relevant risk. An unvaccinated or under-vaccinated dog that encounters a distempered raccoon or its droppings can contract the virus. Canine distemper vaccination is considered a core vaccine for dogs and is highly effective, which is why distemper in pet dogs has become relatively uncommon in countries with widespread vaccination programs. But the virus still circulates constantly in wildlife, so the protection only holds as long as the dog’s vaccinations are up to date. Puppies that have not yet completed their full vaccine series are particularly vulnerable.

The concern extends to exotic pets as well. Ferrets are extremely susceptible to CDV and almost always die if infected. Zoo populations face threats too: a major outbreak among free-ranging raccoons near a suburban zoo in the United States revealed that genetically distinct CDV lineages caused separate waves of disease in 1998, 2000, and 2001, with the 2001 virus showing different biological behavior in brain and lung tissue compared to the earlier strains.⁶ The genetic diversity of CDV circulating in wildlife means that the virus is not a single static threat but an evolving one.

Distemper in Raccoon Populations

Distemper does not burn through raccoon populations at a steady rate. Instead, it tends to surge and recede in dramatic cycles. A long-term study of wild raccoons in Hokkaido, Japan, tested over 600 blood samples collected across multiple years and found high rates of exposure in certain years and almost none in the years between. Roughly a third of raccoons tested in 2007 showed antibodies to CDV, the rate dropped to near zero between 2008 and 2012, and then it climbed back above 46% in 2021 and 2022.⁷ That pattern suggests the virus erupts when enough susceptible animals accumulate in the population, causes widespread infection, leaves survivors with immunity, and then fades until a new generation of unprotected raccoons builds up.

These epidemic waves can cause significant die-offs. In Berlin, the first major European outbreak among free-ranging raccoons ran from late 2012 through mid-2013; of 97 raccoons collected from the urban area, 74 tested positive for CDV.⁸ In North America, where raccoon populations are denser and the virus is well established, distemper outbreaks are a recurring part of the ecological cycle. They can temporarily reduce local raccoon numbers, but raccoons reproduce quickly enough that populations typically bounce back within a few years, setting the stage for the next wave.

Genetic Diversity of CDV in Raccoons

One wrinkle that complicates the picture is that CDV is not a single uniform virus. Multiple genetic lineages circulate simultaneously, and different lineages can behave differently in terms of how they spread, which species they hit hardest, and how severe the disease is. Research in Germany found that CDV strains from raccoons and CDV strains from red foxes during overlapping time periods belonged to entirely different genetic lineages, suggesting that the virus can circulate in semi-independent chains within different host species even in the same geographic area.⁹ In New England, the CDV clade found in multiple wildlife species was genetically distinct from the strains used in commercial vaccines.⁵

This diversity matters for two reasons. First, it makes surveillance harder because you cannot simply test for one strain and assume you have the full picture. Second, it raises questions about how well existing vaccines, all derived from historical CDV strains, protect against the lineages currently circulating in the wild. So far, commercially available dog vaccines appear to provide broad enough protection, but the gap between vaccine strains and wild strains is something researchers keep an eye on.

How Distemper Is Diagnosed

In a living raccoon, there is no quick field test for distemper. Wildlife professionals and veterinarians rely on a combination of clinical signs and laboratory confirmation. The gold-standard test uses a molecular technique called RT-qPCR on blood samples, which can detect viral genetic material with high accuracy. Researchers studying captive raccoons that died of distemper confirmed the diagnosis using a battery of methods, including PCR on blood, histopathology, and immunohistochemistry on tissue samples. They found distinctive microscopic lesions: depletion of immune cells in lymph nodes and characteristic viral inclusions in the cells lining the small intestine.¹⁰

In practical terms, most wild raccoons displaying advanced neurological symptoms are diagnosed presumptively based on behavior and appearance, with lab confirmation happening after the animal has died or been euthanized. Post-mortem examination remains the most reliable way to confirm distemper in wildlife, since a living wild raccoon is not exactly cooperative during blood draws.

Can Distempered Raccoons Be Treated or Vaccinated?

There is no antiviral drug that cures distemper. Once a raccoon has reached the neurological stage, the damage to the brain is generally irreversible, and the prognosis is extremely poor. Wildlife rehabilitators sometimes encounter raccoons in the early respiratory phase and attempt supportive care, such as fluids, antibiotics for secondary infections, and nutritional support, but the success rate for animals that go on to develop neurological signs is dismal. Most wildlife rehabilitation centers will euthanize raccoons with confirmed or strongly suspected distemper both to end the animal’s suffering and to prevent the virus from spreading to other animals in care.

Vaccination is sometimes used in rehabilitation settings to protect other raccoons being housed at the facility. Research on captive wild-caught raccoons given a two-dose vaccination regimen showed moderate immune responses: about two-thirds of previously unexposed raccoons developed antibody levels that might be protective roughly a month after the booster dose.¹¹ The word “might” is important there. Because the study did not expose the vaccinated raccoons to the actual virus afterward, it remains unclear whether those antibody levels would truly prevent infection. Modified-live vaccines can also carry some risk when used in wildlife species they were not designed for, so the decision to vaccinate raccoons in rehabilitation is made carefully and on a case-by-case basis.

There is also a complication with parvovirus vaccines given alongside distemper vaccines. A study of raccoons vaccinated with both modified-live distemper and feline panleukopenia vaccines found that the immune response to the parvovirus component was much less dramatic than the distemper response, and two animals showed outright vaccine failure for that component.¹² Raccoon immune systems do not respond to every vaccine the way a dog’s does, which makes wildlife vaccination a more uncertain proposition.

What to Do If You Find a Sick Raccoon

If you encounter a raccoon that appears disoriented, is walking in circles, seems unafraid of humans, or is stumbling and falling, the single most important thing is to keep your distance. Do not attempt to touch, feed, or relocate the animal. Even though CDV itself is not a threat to you, the raccoon may also be carrying rabies, parasites, or bacteria that are transmissible, and a confused animal can bite or scratch unpredictably.

Call your local animal control department, wildlife agency, or a licensed wildlife rehabilitator. In many jurisdictions, animal control officers are trained to capture and assess sick wildlife, and they can arrange for testing when appropriate. Keep pets, especially dogs, away from the area. If your dog has been in contact with a raccoon or its waste and is not current on vaccinations, contact your veterinarian promptly.

There is no need to disinfect your entire property after seeing a distempered raccoon pass through, but cleaning up raccoon latrines (the communal defecation sites raccoons favor) is good practice regardless of distemper, since those sites also harbor roundworm eggs and other pathogens. The virus itself does not last long in the environment, especially in warm weather or direct sunlight, but fecal material in sheltered, shaded locations can remain a source of various infections for longer.

Urban Raccoons and the Human Footprint

Cities have created ideal conditions for distemper to cycle through raccoon populations. Urban and suburban raccoons live at much higher densities than their rural counterparts, share food sources like dumpsters and pet food left outdoors, and den in closer quarters. All of this accelerates transmission. The Berlin outbreak illustrates the urban dimension: it was the first major CDV event among free-ranging raccoons in Europe, and it played out entirely within a city environment, also involving native carnivores sharing that urban space.⁸

For residents of neighborhoods with visible raccoon activity, the practical implication is that distemper outbreaks are a predictable, recurring event rather than a rare emergency. Securing garbage, removing outdoor pet food at night, and sealing entry points to attics and crawl spaces will not prevent distemper from circulating in the local raccoon population, but it will reduce the density of raccoons on your property and lower the chance that your pets encounter a sick one. Keeping dogs vaccinated is far and away the most effective protection available to you, and it is one of the cheapest routine veterinary interventions there is.