Canine Distemper Virus (CDV) is similar to the human measles virus and can affect the skin, immune system and neurologic system in dogs. It is not as common as it once was and outbreaks have diminished significantly because of the effective practice of vaccinating animals against this disease. Vaccinating your dog to protect it against distemper not only helps protect him, but also inhibits his ability to continue spreading it to the rest of the dog population. This highly contagious disease is spread by aerosolized particles and by direct contact with an infected animal. Due to its highly contagious nature infected animals have to be isolated once they are diagnosed.
My first experience with Distemper Virus occurred when I was a junior in veterinary school during an internship in Las Vegas. The patient was a beautiful, young Weimaraner named Sage. She had the typical lesions associated with the disease: thickened pads on her feet and nose (hyperkeratosis), upper respiratory signs (discharge from eyes and nose, coughing), and gastrointestinal signs (vomiting, diarrhea). She also presented with neurologic abnormalities in the form of shaking and uncontrollable tremors. Despite how sick she was Sage always wagged her tail when she had visitors in isolation, a true inspiration to remember when life seems tough or unfair. Many infected dogs have such a grave prognosis that euthanasia is sometimes the most humane option for some owners. Thankfully, Sage was lucky to have received medical care early in the course of her disease and she was able to overcome the disease and go on to live a normal, happy life.
The clinical signs of this disease can resemble other diseases, most notably rabies, so it is important to run tests to find diagnose this infection. There are different ways to test for CDV including assessing tissue samples, cerebrospinal fluid from the spinal cord, and blood tests (PCR amplification of DNA, and real-time PCR). Some of these samples can only be collected after the animal is deceased. Some tests are better than others because a recent CDV vaccination can cause a positive result for CDV on some tests even though the dog is not infected. Real-time PCR has been shown to be effective in differentiating between true CDV infections versus interference from recent vaccination. In any case, differentiating this infection from rabies and other diseases is of the utmost importance.
Why should you vaccinate your dog? Even if your dog does not have much interaction with other dogs, the virus can be harbored in other wildlife and a visit from a coyote or other critter to your backyard could put your dog at risk. Most viruses do not have specific treatments, including CDV, so once infected the only treatment available at this time are supportive care (IV fluids, antibiotics, pain control, antiemetics). The best way to keep your dog safe from CDV is to follow recommended vaccination protocols.
The distemper vaccine usually comes as a combination injection with parvovirus, adenovirus and parainfluenza virus vaccines, and occasionally includes other vaccines in the same injection as well. By vaccinating your dog you also decrease the chance of the virus being passed on to other dogs, which is why this vaccination is often required by boarding facilities, even though it is not required by law. The debates surrounding appropriate vaccination protocol are endless, for example; should vaccinations be given every year or every three years? One solution to avoid vaccination is to have a titer test performed. A titer test measures the amount of immunity the animal has remaining from the last vaccination, and if that level remains high enough CDV vaccinations can be skipped for that year.
There is a wealth of information available on the internet regarding this and similar subjects, some sources being more reliable than others. For more information on CDV please visit the American Veterinary Medical Association website: www.avma.org