Distemper in Dogs: Causes, Symptoms & Treatment

Rates of disease have dropped significantly in the past 40 years, but canine distemper remains prevalent in populations with low vaccination rates such as in shelters or rescue environments or in areas with stray dogs. Let’s learn more about canine distemper in dogs so we can keep our pets safe.

What is distemper in dogs and what causes it?

Distemper is a viral disease that affects puppies and adult dogs. It is caused by a paramyxovirus, similar to the human measles virus. The canine distemper virus is relatively fragile outside of the host and is spread via aerosolized droplets from the infected animal.

Canine distemper can also be transmitted across the placenta to puppies from infected dams. The virus can affect a variety of hosts including foxes, raccoons, otters, and skunks. An infected dog can shed the virus for weeks to months.

Once contracted by a dog, the virus will replicate within the lymphatic tissue of the respiratory tract. The canine distemper virus will then infect all lymphatic tissues within the body. This causes infection of the respiratory, neurological, gastrointestinal, and urogenital organs.

Symptoms of distemper in dogs

Distemper in puppies and adult dogs will cause a variety of clinical signs. A transient fever will develop between 3-6 days after the canine distemper infection is contracted.

At this time, there may also be a decrease in white blood cells, specifically the lymphocytes with canine distemper.

Many times, this phase is missed due to a lack of significant clinical signs, and many domestic dogs may simply refuse meals but appear otherwise normal. This fever will improve without intervention.

A second fever may develop several days after the initial fever resolves. This may also be accompanied by a variety of clinical signs including nasal discharge, ocular discharge, lethargy, and poor appetite.

The nasal discharge is often clear but the ocular discharge is typically thick and mucopurulent. Gastrointestinal and respiratory signs may also be exhibited.

Dogs can develop skin disease with pustular dermatitis. Dogs with central nervous system involvement will show neurological signs associated with encephalomyelitis.

Neurologic signs affecting the nervous system include involuntary muscle twitching, seizures, circling, nystagmus, and paresis to paralysis. These neurological signs of canine distemper typically develop with longer courses of the disease and may present weeks to months after the initial infection.

Dogs that survive the acute phase of the disease will often develop hyperkeratosis of the nose and foot pads. Enamel hypoplasia will be evident in younger infected animals. Once dogs have recovered, they no longer carry the virus nor are infectious.

How to diagnose distemper in dogs?

Canine distemper in dogs should be considered in any dog exhibiting a fever and multisystemic clinical signs.

Unvaccinated dogs are at the highest risk of contracting the disease.

Testing for the canine distemper virus involves PCR and antibody detection tests. These utilize ELISA or IFA to confirm the presence of the virus or antibodies which target the virus.

Testing for the canine distemper virus is performed on smears made from the conjunctival, tracheal, nasal, or vaginal mucus membranes. Urine samples and bone marrow aspirates may also be utilized for testing.

Some tests such as PCR may have difficulty distinguishing natural infection from the presence of the virus secondary to vaccination.

High levels of antibodies within the cerebral spinal fluid are much more common with natural infection than vaccination. Biopsies of the foot pads or skin on the neck may be used for viral antigen IFA.

Post-mortem, distemper in dogs is diagnosed by the presence of characteristic lesions in the tissues alongside IFA or FISH (fluorescent in situ hybridization).

Treatment for distemper in dogs

As with most viral diseases, treatment of the canine distemper virus is largely composed of supportive care as there is no single treatment for distemper that has proven to be successful. Infected dogs will require intravenous fluids to support hydration and proper nutrition.

Many dogs are susceptible to a secondary bacterial infection, therefore, broad-spectrum antimicrobials may be used prophylactically. Dogs with CNS signs will often require anti-seizure medications.

Antiviral agents are available and have shown some promise for dogs with distemper, but these are not yet widely used or available.

Once acute neurological signs develop within the central nervous systems, distemper treatment is often unsuccessful.

With timely and aggressive care, dogs may recover from the distemper virus but can have lasting neurologic symptoms and side effects. The disease has high rates of fatality, 80% in puppies and 50% in adult dogs.

How to prevent distemper in dogs?

Widespread distemper vaccinations have led to a reduction in the number of cases of distemper. Puppies are immunized with a modified live virus when they are 6 weeks old and every 3-4 weeks until they are 16 weeks old.

After booster vaccination at one year of age, most MLV distemper vaccines will provide up to 3 years of immunity.

Young puppies that are not completely vaccinated must be kept away from public areas where other dogs frequent to prevent exposure to any serious disease including the highly contagious distemper, parvovirus, kennel cough, and others.

Dogs that are infected with distemper must be kept in isolation from other animals as the disease is highly contagious.

Any surface the dog has encountered must be cleaned thoroughly with disinfectants including lipid solvents, phenols, and quaternary ammonium compounds.