How do dogs get distemper?

I work with worried owners and shelter teams often enough to know that canine distemper is one of those infectious diseases that can feel sudden and overwhelming. Understanding how dogs get infected helps you protect puppies, rescues, and the wider dog community without panic—so you can act quickly, make sensible choices, and reduce both emotional and financial fallout.

Why every dog owner should take distemper seriously

Puppies and any dog without current vaccinations are the most vulnerable; maternal antibodies may offer short protection, but that fades and leaves a window of susceptibility that I see commonly in rescue intakes. In shelters, rescues, boarding facilities and multi-dog homes, a single infected dog may expose many animals because the virus spreads through close contact and the environment. When I consult with owners after an outbreak, the consequences are often more than medical: long hospital stays, behavior changes from prolonged isolation, and the distress of seeing a pet decline—all of which carry real costs and heartache. Travel, rehoming and encounters with strays increase the odds that an exposed dog will bring infection into previously healthy groups, so prevention matters to every dog lover who moves their dog between places or brings new dogs into a household.

How dogs catch distemper — a concise explanation

Canine distemper virus usually travels in respiratory droplets when an infected dog coughs, sneezes or has close face-to-face contact. Direct contact with an infected animal—licking, shared feeding bowls, or communal sleeping areas—can spread it. The virus can also survive for a time on surfaces like bowls, bedding or leashes (fomites), so crowded or poorly cleaned spaces raise risk. Unvaccinated dogs, puppies whose vaccine series isn’t complete, and dogs with weakened immune systems are most likely to catch and show disease. People are very unlikely to catch distemper; it is not typically a human infection, though it remains a serious canine health problem.

Inside the virus: how distemper infects and harms dogs

Canine distemper virus (CDV) is in the paramyxovirus family; this set of viruses tends to target respiratory tissues first. After inhalation, the virus likely attaches to cells in the nose and throat and then reaches local lymphoid tissue where it may multiply. From there it can spread through the bloodstream and reach multiple organ systems—the lungs, intestinal tract and, importantly, the brain—so the disease often looks multisystemic. The nervous-system involvement is what makes some cases prolonged and difficult, because nerve damage can produce tremors, abnormal movements, or seizures that may persist after infection.

Vaccination teaches the dog’s immune system to recognize and control the virus before it spreads systemically. Modified-live vaccines commonly used in clinics stimulate both antibody and cellular responses that reduce the chance of infection and, if infection occurs, often lessen severity. Puppies are given a series of shots because maternal antibodies can interfere with early vaccines; the series strategy increases the odds of building protective immunity as maternal protection wanes.

When distemper spreads: timing, hotspots, and risk factors

Outbreaks are most likely where dogs are packed together or turnover is fast: shelters, municipal pounds, kennels, dog-daycare facilities and busy adoption events. Low herd immunity—meaning many dogs that are unvaccinated or overdue for boosters—creates fertile ground for wider transmission. I also see outbreaks linked to stress: dogs under nutritional strain, recent transport, or concurrent infections are less able to fight off exposure, and that makes transmission more efficient. While distemper can occur year-round, clustering in a region or season may follow increased movement of dogs (for example, mass rescue operations after disasters) or seasonal patterns in shelter intake.

Recognizing symptoms: medical red flags that require a vet

The earliest signs often mimic a respiratory infection: a low-grade fever, runny eyes and nose, and a cough that may be soft or harsh. Gastrointestinal signs such as vomiting, diarrhea and reduced appetite may appear as the infection spreads to the gut. One distinctive sign I look for is thickening of the footpads or nose in some dogs; it’s not universal but can be a clue. Neurological signs—muscle twitching, tremors, unsteady gait (ataxia), confusion or seizures—suggest the virus has reached the nervous system and are a serious escalation.

Certain features require immediate veterinary attention: a persistent high fever despite treatment, rapid dehydration from vomiting or diarrhea, prolonged or repeated seizures (status epilepticus), or sudden severe respiratory distress. These are emergency red flags because they often signal complications that may be life-threatening without aggressive supportive care.

If you suspect distemper: immediate steps to take

1. Isolate the affected dog from other animals right away. Keep it in a quiet room or crate with minimal, one-person handling until you reach a vet.
2. Call your veterinarian and be ready to report the dog’s full vaccination history, recent contacts, and any travel or shelter exposure. Early veterinary guidance reduces spread and improves outcomes.
3. Follow recommended testing and treatment. A vet may suggest PCR testing of swabs or blood work and may check antibody titers; treatments are supportive—fluids, nutrition, antibiotics for secondary infections, and anticonvulsants for seizures—because there isn’t a widely available antiviral that reliably cures CDV.
4. Provide supportive home care only under veterinary instruction: keep the dog warm and hydrated, monitor temperature and breathing, and administer prescribed medications on schedule. If neurological signs or severe dehydration develop, transport immediately to emergency care.

Keeping your household and other pets safe during infection

Quarantine duration commonly recommended is at least several weeks because dogs can shed virus for a prolonged period before and after clinical signs—many clinics suggest maintaining isolation for about four weeks or until your veterinarian confirms the dog is no longer shedding by testing or gives clearance. During quarantine, check and record temperature twice daily and note appetite, stool quality and any new neurologic signs.

Cleaning is critical. Use a freshly mixed solution of household bleach (roughly one part bleach to thirty parts water) on nonporous surfaces and allow adequate contact time—usually several minutes—before rinsing. Accelerated hydrogen peroxide products that are labeled as veterinary-grade can be effective and are less corrosive; follow product directions. Textiles, porous bedding and soft toys that can’t be disinfected should be laundered on hot cycles or discarded. Always wear disposable gloves when handling contaminated items and dispose of waste safely.

Reintroducing a recovered dog to other dogs should be stepwise. First, confirm with your veterinarian that the dog is clinically well and, where possible, that shedding has ceased or that a vaccine booster and time period have passed to reduce risk. Start with calm, vaccinated dogs in controlled, short outdoor meetings while you watch for any recurrent signs. Avoid high-risk settings—dog parks, group daycare—until the dog is fully cleared and up-to-date on vaccinations. Also prepare for behavior changes: after weeks of isolation some dogs may be anxious about interactions, so slow, positive reintroduction and short training sessions can help rebuild social skills.

Practical supplies and protective gear vets recommend

• A digital pet thermometer and a simple record notebook for twice-daily checks of temperature, appetite and behavior.
• Basic first-aid supplies: absorbent towels, disposable gloves, saline for eye/nose cleaning if advised, and a scale or way to estimate body weight for fluid dosing guidance.
• Disinfectants suitable for veterinary use—freshly mixed household bleach (see label) and an accelerated hydrogen peroxide cleaner—and spare dedicated bowls, bedding and crate for isolation.
• Personal protective equipment for handlers: disposable gloves, and if you’re caring for a very sick dog, a plastic apron or gown to prevent cross-contamination during feeding and cleaning.

References and further reading

• AAHA Canine Vaccination Guidelines (2020). American Animal Hospital Association: Canine Immunization Guidelines—practical recommendations for vaccine timing and herd immunity strategies.
• Merck Veterinary Manual: “Canine Distemper”—clinical overview, diagnosis and supportive care approaches for CDV.
• American Veterinary Medical Association (AVMA): Infectious Diseases—resources on management of contagious diseases in shelters and community settings.
• Greene, C.E., Appel, M.J. (2012). “Canine Distemper.” In Infectious Diseases of the Dog and Cat, 4th ed. Elsevier—detailed virology and systemic effects of CDV.