Canine distemper typically starts with watery or greenish discharge from the eyes and nose, followed by lethargy and loss of appetite within one to two weeks of infection. As the disease progresses, it can affect the lungs, gut, skin, and brain, producing a wide range of visible symptoms that change over time. The mortality rate is about 50% in adult dogs and 80% in puppies, making early recognition critical.
Early Signs: Discharge, Fever, and Lethargy
The first thing most owners notice is discharge from both the eyes and nose. It often starts clear and thin, then thickens to a yellow or green consistency as secondary bacterial infections take hold. Your dog may look like they have a bad cold, with crusty buildup around the nostrils and eyes that needs to be wiped away frequently.
Alongside the discharge, dogs typically lose interest in food and seem unusually tired. Fever comes and goes in the early stage, sometimes spiking and then dropping before spiking again. This two-phase fever pattern can make owners think their dog is recovering when the disease is actually still progressing. These initial signs usually appear one to two weeks after the dog was exposed to the virus.
Respiratory and Digestive Symptoms
As the virus moves deeper into the respiratory tract, a cough develops. It may start dry and progress to a wet, productive cough if secondary bacterial pneumonia sets in. Dogs with pneumonia often show labored breathing, a visible effort with each inhale, and may breathe through their mouth. Fever, deeper lethargy, and a complete refusal to eat are strong signals that a bacterial infection has layered on top of the viral one.
Digestive involvement brings vomiting and diarrhea, which can range from mild to severe. The diarrhea may be watery or bloody. Combined with not eating, this creates a rapid dehydration risk, especially in puppies. A dog showing both respiratory and digestive symptoms at the same time is a particularly concerning picture.
Skin Changes: Hard Pads and Nose
One of distemper’s most distinctive visible signs is thickening and hardening of the paw pads and nose. This is sometimes called “hard pad disease.” The normally soft, slightly textured paw pads become rough, cracked, and overgrown with excess skin. The nose leather develops a similar dry, crusty texture. These skin changes tend to appear weeks into the illness and result from the virus directly damaging the skin cells in those areas. Even in dogs that recover, the hardened pads and nose may persist as permanent changes.
Neurological Signs
The most alarming phase of distemper is when the virus reaches the nervous system. Neurological symptoms can appear while a dog is still fighting respiratory illness, or they can emerge weeks or even months later in dogs that seemed to be recovering. Once these signs start, they tend to get progressively worse.
The hallmark neurological sign is myoclonus: rhythmic, involuntary muscle twitches that often affect the head, limbs, or jaw. These twitches are constant and continue even while the dog sleeps. One particularly recognizable form is “chewing gum fits,” where the jaw makes repetitive chewing motions accompanied by drooling, sometimes escalating into full seizures.
Other neurological signs include:
- Head tilt and walking in circles
- Loss of coordination, stumbling or swaying while walking
- Partial or complete paralysis, particularly in the hind legs
- Seizures that can vary from mild tremors to full convulsions
Dogs displaying neurological symptoms have a poor prognosis. Those that survive often carry permanent damage, including lifelong muscle twitches, difficulty walking, or recurring seizures.
What Survivors Look Like Long-Term
Dogs that survive distemper can carry lasting reminders of the infection. Permanent neurological issues like persistent muscle twitches and coordination problems are common. The hardened paw pads and nose may never fully return to normal. Dogs that were infected while their adult teeth were still developing often end up with enamel hypoplasia, a condition where the teeth come in pitted, discolored, and poorly formed because the virus damaged the tooth buds.
Some survivors also develop chronic eye problems, including inflammation in the back of the eye that can affect vision. Because distemper suppresses the immune system, recovered dogs may be more vulnerable to other infections in the months that follow. And while most dogs clear the virus within a few weeks to a few months after recovery, some continue shedding it for much longer. One documented case found a dog still testing positive in urine samples 17 months after infection, though shedding periods of 60 to 90 days are more typical.
How Distemper Is Confirmed
Distemper can look similar to other respiratory illnesses, kennel cough, or even poisoning when neurological signs are involved. A veterinarian will typically run a PCR test, which detects the virus’s genetic material and is considered the most reliable diagnostic tool. Blood antibody levels can help determine whether a dog has been exposed and whether their immune system is mounting a response. Chest X-rays and bloodwork may also be used to check for pneumonia or secondary infections.
A dog with high antibody levels and a negative PCR result is generally considered immune rather than actively infected, an important distinction for dogs with uncertain vaccination histories.
Prevention Through Vaccination
Distemper is classified as a core vaccine, meaning it’s recommended for every dog regardless of lifestyle. Puppies 16 weeks and younger receive at least three doses of a combination vaccine (which also covers parvovirus and adenovirus) spaced two to four weeks apart, starting as early as six weeks old. Dogs older than 16 weeks who were never vaccinated need two doses, two to four weeks apart. After the initial series, a booster is given within one year, then every three years after that.
Puppies are at highest risk in the gap between losing their mother’s antibodies and building full vaccine immunity, which is why the multi-dose puppy schedule exists. Unvaccinated dogs of any age, along with shelter dogs and strays, remain vulnerable.
How Dogs Catch It
The virus spreads through airborne droplets from coughing or sneezing, as well as through shared food bowls, water dishes, and direct contact with an infected dog’s bodily fluids. An infected dog can be contagious before showing any symptoms and continues shedding the virus in feces for one to two weeks typically, though shedding can persist for three to four months in some cases. The virus doesn’t survive long in the environment and is killed by most common disinfectants, so transmission almost always requires relatively close contact with an infected animal or its fresh secretions.