Canine Distemper: Still A Dangerous Threat

Although most people have heard of canine distemper, many people don’t know just how dangerous this disease really is.

During the first half of the twentieth century, canine distemper was by far the most common fatal disease in dogs. Even after a vaccine was developed against it (which has been in general use since the 1960’s), to this day distemper still has a death rate as high as 80% in puppies. Dogs who are lucky enough to survive canine distemper often have irreversible neurological damage.

Distemper in dogs is caused by a virus that’s closely related to the human measles virus. Highly contagious, this virus primarily strikes puppies and older, unvaccinated dogs, but it can also be found in ferrets and wildlife (including wolves, foxes, coyotes, skunks, raccoons, weasels, minks, seals, and wild boars).

When it comes to canine distemper, unfortunately we often tend to be lulled into a false sense of security due to the fact that distemper has been around for so long, and the vaccine against it is so effective. We seem to think this disease is just old history, like polio in humans.

Thinking this way would be a grave mistake. Canine distemper is not only still around, it’s a very real threat – a highly contagious virus with a high fatality rate that is still killing dogs and puppies, and it should never be underestimated.

How Are Dogs Infected With Canine Distemper?

Most puppies and dogs become infected with canine distemper through exposure to airborne droplets resulting from the coughing and sneezing of an infected animal (including wildlife). However, the distemper virus can also be present in urine, saliva, and feces, which means it can be transmitted through shared bedding, water, food bowls, visits to the dog park, and areas frequented by wild animals. Puppies can also be infected from their mother, either while they are still in utero or through their mother’s milk.

Infected dogs can shed the virus for weeks to months, even if they are not yet showing signs of being sick. Fortunately, outside the host the virus that causes distemper is highly susceptible to most disinfectants, direct sunlight, and heat, making it much easier to kill than other infectious canine viruses like parvovirus.

What Happens In A Dog With Canine Distemper

Once a dog is exposed to the canine distemper virus, it immediately invades the tonsils and lymph nodes. Once inside the lymph nodes, the virus is free to begin moving throughout the entire body via the bloodstream and lymphatic system.

After about a week, it begins to infect the lungs, gastrointestinal tract, and bladder, and eventually moves to the central nervous system where it affects the brain, nerves, and spinal cord. The time from initial exposure to when symptoms actually appear can be anywhere from 3 days to 5 weeks. In puppies and dogs with weakened immune systems, canine distemper can cause death within 2-5 weeks of exposure. Death rates are up to 75% in adult dogs, and up to 80% in puppies.

In the first stages of the disease, dogs and puppies may display the following symptoms:

• High fever (103 degrees or higher)
• Red or watery eyes
• Clear nasal discharge
• Greenish-white discharge from the eyes
• Persistent cough
• Loss of appetite
• Vomiting
• Diarrhea
• Lethargy (no energy)
• Labored breathing
• Pneumonia
• Weight loss (particularly in puppies)

In these early stages, canine distemper is often misdiagnosed as kennel cough.

As the disease progresses, the virus begins a full attack on the nervous system, which can lead to these symptoms:

• Seizures
• Severe depression
• Agitated behavior (pacing, circling, unable to sit still)
• Aggressiveness
• Heightened sensitivity to sensory stimuli (light, sound, and touch)
• Tremors
• Head tilt
• Uncoordinated movements, wobbling, disorientation
• Deterioration of mental abilities
• Partial or complete paralysis
• Blindness

Additionally, canine distemper can cause an unusual thickening of the skin on the dog’s foot pads and on the bridge of the nose (called “hyperkeratosis”), leading to distemper’s nickname: “Hard Pad Disease”. In puppies who survive, permanent damage can also occur to their tooth enamel.

How Is Canine Distemper Diagnosed?

Canine distemper is notoriously difficult to diagnose. Since definitive testing for distemper can be expensive, unreliable, and in some cases detrimental to the patient (especially in puppies), most veterinarians diagnose it through clinical signs and other laboratory testing, including:

• Blood work to evaluate kidney and liver function, blood sugar levels, and white blood cell count.
• A urinalysis to check for evidence of the virus in urine sediment.
• X-rays of the chest to rule out pneumonia.

Although expensive, a CT scan or MRI may also be done to look for brain lesions, which are common in dogs with distemper.

Treatment Of Canine Distemper

Sadly, there is no cure for canine distemper. Treatment consists of hospitalization and a customized plan for supportive therapy (IV fluids to correct dehydration, antibiotics to prevent secondary bacterial infections, cough suppressants, medications to reduce nausea and diarrhea, pain medication, and anti-seizure medication), while trying to keep the dog as comfortable as possible while his body fights the virus.

Since distemper is so contagious, and dogs who recover from the disease can continue to shed the virus in their saliva, urine, and feces for months afterwards, surviving dogs are often quarantined at home for weeks to months and kept away from other dogs. Surviving dogs will often experience permanent “hard pad disease” and tooth enamel problems, as well as permanent neurological damage and issues with their vision.

These dogs are the lucky ones; many dogs and puppies who are severely affected by canine distemper are humanely euthanized to relieve their suffering.

Preventing Distemper In Your Dog

Prevention of canine distemper is very straightforward: vaccination. The vaccines that exist now for preventing distemper are manufactured from live, weakened strains of the canine distemper virus and provide long-lasting immunity against the disease.

When it comes to vaccinating against distemper, it’s important to understand that all dogs should receive this vaccine as puppies, if at all possible. According to the most recent guidelines released by the AVMA in 2011, puppies should receive their first distemper vaccine between the ages of 6 and 8 weeks, followed by a second vaccine 4 weeks later, then a final vaccine between the ages of 14 and 16 weeks. An initial booster should be given one year later, followed by one more booster in 3 to 5 years. For healthy adult dogs, one vaccine should be sufficient to provide protection for at least 5 years.

Although the distemper vaccine is generally combined with other vaccines (usually against parvo, parainfluenza, canine hepatitis, leptospirosis, and sometimes coronavirus), keep in mind that you can choose to have these vaccines given separately to avoid overwhelming your puppy’s immune system. Then when your dog is an adult, rather than just routinely re-vaccinating him, you can elect to have a blood test called a “titer” done to see if he still has protection against the disease. For more information on vaccines and developing the safest vaccination protocol for your puppy or dog, please check out my previous article “Vaccinations: Too Much Of A Good Thing?”

In addition to vaccination, there are also other ways to protect your puppy or dog against canine distemper:

• Create a strong immune system in your puppy or adult dog through a high-quality diet free of chemical additives and preservatives.
• Use caution when socializing puppies at puppy classes, parks, doggie day care, dog shows, or other places where lots of dogs congregate.
• Avoid contact with wildlife.

Canine Distemper: Taking It Seriously

Although the prevalence of canine distemper has dramatically decreased over the last 50 years due to the availability of quality vaccines, it still remains a major threat to dogs and puppies, especially those in rural areas, animal shelters, and pet stores. Outbreaks continue to occur in the United States and throughout the world, with tragic results.

Don’t be tempted into thinking that canine distemper could never happen to your dog… make sure your puppy receives his or her first vaccine between 6 and 8 weeks old, and be sure to complete the vaccination series. If your adult dog has not had a booster for longer than 5 years, have a titer test done to make sure he or she is still protected. It will be well worth the effort to give your dog a fighting chance against this deadly disease.

 In loving memory of puppies Apollo and Zeus.

Have you ever had a dog with canine distemper? Please share your story with us in the comments below!